Renderings are a must these days, according to Nathan Porter of Porterbuilt Street Rods: "We won't do a build without one. It literally puts us and the client on the same page." These days, renderings are quickly becoming the first step in a long build process. But what exactly is it and why should you have one done? Renderings vary widely in media, from 3D models to artistic marker and chalk drawings, but they all allow you to see your project finished before it's started.

With a rendering comes value. With shop rates heading through the roof, it can save you time and money. Your artist can move a bumper or change the stance in the drawing-without ever having the builder pick up a tool. Simply put, a rendering allows you to see if your ideas will work and can keep you inspired for the long build ahead.

How Do I Get Started?
Find the right artist for you. Each has his/her own unique style. You'll probably be working closely with the artist, so make sure your personalities gel.

How Long Does It Take?
This depends on the artist and the type of rendering you are having created. Generally speaking, it will take anywhere from three weeks to six months. The key is to know in advance what you want and make sure to clearly communicate that to your artist.

What Will I Get?
This will vary greatly depending on your artist. Most provide a high-resolution print of the front three-quarters of your vehicle, while others provide additional views, such as the back end to a rear three-quarter view. Be sure to ask your artist ahead of time about what you will receive so you won't be disappointed. Also, the number of test renderings you receive before the final print will also vary; again, ask about this before you commission the project. What Does It Cost?
Prices run from $200 to well over $1,200, depending on the artist and factors including body modifications, degree of detail, and the number of views given on the final product. A basic wheel and color scheme design will obviously be easier (and less expensive) than body mods, customizations, or one-off wheels. You can save yourself some money by already having some of your build specifics decided; if you know which wheels or color scheme you want, you can save on the overall time creating the rendering-and therefore, often, the price.

Quick Thoughts
We're not talking Crayola markers here; check out these three examples of a '69 Camaro, 'cause we're talking serious graphic renderings that look remarkably realistic. In this case, you can see how a few simple changes ranging from wheels to stance to paint scheme can really affect the look and feel. Are you a believer yet? -HD

It was back to the school of higher learning at Meguiars' Headquarters-literally. We spent the day in the classroom and listened with open ears to get the real gist of paint theory and practices with marketing director Mike Pennington playing teacher and leading the way. Pennington drilled us in the process of wet sanding and explained, "a lot of imperfections lie under the clear, between the paint." He went over evaluating the paint surface and deciding if wet sanding is right for you. Pennington didn't try to fool us; he told us wet sanding takes time-and patience-but moreover, just plain practice.

Pennington showed us what to look for and the process through which many paint shops go to get that high-end, show-car quality. Pennington even suggests visiting a local junkyard to practice the fine art of wet sanding. It's too easy to get carried away and end up burning right through your freshly painted sheetmetal. Practicing on a junk panel is a great idea. "It will give you a feel of what and what not to do." No big deal if the panel gets worse. Take it to a paint shop and have them respray it.

While we were at Meguiar's, through its two-liquid-stage cutting and polishing compounds, we achieved a show-car-like finish on even the most measly of paint jobs. This isn't a sure cure for the paint, as some jobs really do need to be repsrayed. But for most jobs, wet sanding and polishing can relieve you of those nasty swirl marks, orange peel, overspray, and fisheyes.

Quick Notes
What it is
Meguiar's two-stage cut and polish compounds

Bottom line
It's not that hard to get a high-end, production finish.

Price (APPROX)
$100

Paint Depth Gauge
Although expensive, paint depth gauges can keep an eye on the thickness of paint. The gauges can guide you and display when the paint is too thin to continue wet sanding or even cutting with compound. Think about it: $400 for a depth gauge or the cost (not to mention labor) of repainting the panel that's too far gone to fix.

THE SHOPPING CART
ITEM	PN	PRICE
Cutting compound	M10501	$30
Polishing compound	M8232	$15
Wool pad	W5000	$30
Foam pad	W8000	$14
Detailing spray	M3416	$7
	TOTAL	$96

Body and paint-these disciplines are often referred to as black arts, unfathomable for all but a gifted few. The bottom line is that a multitude of procedures and techniques must be performed to come up with a sharp-looking paint job, and it takes skill and experience to perform them. It would take a book to lay out everything that goes into the creationof a top-notch paint job, and many have been written. Something like that is beyond the scope of this article, but what we can do is go over some of the important steps that must be performed to achieve success; we've also picked the minds of some industry experts for information that will help you come up with great paint, whether you're paying to have the job done or tackling the task yourself.

The very first thing to consider, of course, is what you want. "It all depends on what the customer wants to pay for," says Jeremiah Becker of Studio Auto Body in Burbank, California. And that, of course, covers a broad range. Paint jobs at outfits like Earl Scheib and Maaco start out at just a few hundred bucks. And something like that may do the trick for you. "Those guys are excellent at spraying," says Tom Prewitt of Resurrection Hot Rods and Customs in Fullerton, California. "They spray 20 cars a day." On the other hand-and we'll discuss this more later-the material usually isn't very good. Prewitt recommends upgrading the material if you can. "They just do a quick sand and paint, so if you take the car apart yourself and scuff up the hard-to-reach areas, you'll get a paint job that's not too bad. It's not what we do, though."

A single-stage paint job like the one Studio performed on our cover car is in the 10 grand range. "There's $1,000 there just in materials," says Robert Becker. "The gallon of paint alone is $400." The rest is all the body filler, sandpaper, tape and masking paper, primer, and most importantly, the man-hours needed to get the car ready for paint. And that's not counting the multiple patch panels that were needed on this car to exorcise the devil rust. At Resurrection, where custom work is the norm, Prewitt says the tab, going from bare metal to paint, is more in the $15-20k range. And at D&P Classic Chevy, where 75 percent of the paint jobs are done as part of a frame-off restoration, you can easily get into 25-30 large on parts, then another 30-40 thousand on labor, which includes paint and body. Again, it all depends on what you want-and what you want to pay for.

On the other hand, what if you want to do it yourself? The first question to ask is, are your skills up to creating the type of paint job you want? And that begins with the bodywork. Our favorite Chevys are often 30 to 50 years old, so rust damage is often an issue, and panel replacement isn't a job to be taken lightly.

"If you cheap out on your paint job and you're not happy with it," says Darryl Nance of D&P, "you'll just get disillusioned and sell the car." None of us want that. The lesson here is to do your research, take your time, and get the job done right. This is our contribution to the process, with the hope that you'll come out with a great-looking Chevy at the end of it.

Quick Notes
The Query
What goes into prepping and painting a vintage chevy?

Bottom Line
There's a lot to keep straight, but the payoff is an eye-catching coat of paint.

Cost
Affordable to out-of-control for a custom or body-off paint job

Counting The Cost
There's a lot more to painting than just paint, so we hit a local paint dealer-Coast Airbrush in Anaheim, California-to see what it would cost to paint a theoretical car. With Resurrection Hot Rods and Customs' Tom Prewitt as our consultant, we dreamed up a '68 Camaro that would be adorned in House of Kolor Apple Red with Snowhite Pearl rally strips. Coast owner Dave Monig pulled everything we'd need off the shelves, laid it out for us, then ran up an estimate.

We expected the paint and primer to count for a big chunk of the total, but were surprised that the substances needed to make them work-the activators, catalysts, and reducers-cost half as much again. As with most things, the little things will get you. It's good to know you'll spend more than $100 on sandpaper before starting, and that could easily double if you're taking a car down to bare metal. And you're looking at almost that much again just for tape and masking paper.

We did include a couple of sanding blocks in the total but didn't include power tools, like a grinding wheel, DA sander, or block sander-not to mention a paint gun. So if you, like us, have ever wondered why a paint job costs so much, now you have a better idea of where all that dough goes.

Primer 101
You might think of primer as just "that stuff beneath the paint," but the undercoats serve several important purposes critical to a good paint job, and there are a variety of undercoat types. First, primer protects the metal from corrosion. Second, it provides the final level of bodywork, filling in minor imperfections in a car's surface. Third, it seals the prep work below, and fourth, it provides a uniform surface for the paint to adhere. These are the types of primer and what they do:

*Self-Etching Primers/Epoxy Primers provide adhesion to the metal surface and all products that follow and also corrosion resistance. If you take a car down to bare metal, one of these should be used. This primer is generally not sanded.

*Primer Surfacers fill small scratches and imperfections in the metal surface. They dry quickly and sand easily-in fact, several layers are often applied and sanded until a satisfactory level of straightness is achieved. Some primer/surfacers have direct-to-metal etching qualities-read the tech sheet to be sure.

*Primer Sealers seal the preparation layers below and provide a uniform bonding layer for the finish coats. They can be tinted for color-matching purposes and are not sanded as long as the paint is applied within the curing window. If primer sealer is allowed to fully cure, some may require sanding before painting; again, follow the manufacturer's recommendations.

Normally, you'd think the smoother a surface is sanded the better. Not so, says our man Prewitt. We'll cover this more elsewhere, but paint products make two types of bonds: chemical and physical. If you sand primer too smooth, the next layer can't make the necessary physical bond. "Under a microscope, you see little teeth sticking up," he tells us. "That makes the physical bond." The bottom line is if you sand primer too smooth, the following layers can't stick. In a nutshell, 400-grit is as fine as you need to get during the final wet-sanding of the primer surfacer.

New Metal
Since we covered a patch panel installation elsewhere in this issue, we decided to contact Mark Vogt, general manager of Classic Industries, an OER distributor, to talk a bit about aftermarket sheetmetal. "Nobody beats a panel straight anymore," says Vogt. "There's so much good metal to replace it." So what tips does he have for those who decide to replace their metal? "We recommend professional installation on everything, even a fender that bolts on in five places. There are shims to deal with, and the whole thing gets more complicated if you're doing a ground-up. There may be other problems to deal with as well. And I believe in replacing the whole panel rather than a just a quarter skin. It'll blend better, you can make fit better, and it's easier to do, since it goes on at the spot welds." And that black coating aftermarket panels are coated with? "It's not a primer," he reminds us. "The coating is a rust inhibitor and protector for shipping. It has to be removed and the panel primed." What's the biggest problem with replacement sheetmetal? Vogt says "99.9 percent" of complaints are shipping damage. "Don't sign a delivery clear if there's a dent, nick, or anything that shouldn't be there," he says. And what does he say to those who question the fit and finish of aftermarket sheetmetal? "Get original metal if you're building a 100-point resto. If not, no one should know the difference."

Refinish Vs. Custom Paint
So just what is the difference between refinish and custom paints? They're two different strategies for two different purposes," says House of Kolor's training manager Brian Lynch. "The essence of refinish paint is to try to duplicate what was originally on the car, with certain expectations. Most of these paints are fairly simple, Lynch explains. They have an iridescent color (that's a metallic or a pearl to you and me) protected by a layer of clear. The layers of primer, basecoat, and clear are only 4-5 mm thick. With a custom paint, the metallic flakes might measure as much as 6 mm or even larger. "It's a structurally thicker paint job to accommodate thicker flakes and particles needed for the optical effects one sees," Lynch says.

How much thicker? Somewhere in the 10-15 mm range, even higher with graphics. So on one hand, choosing between refinish and custom paint is a matter of simple color preference. On the other hand, since custom paint systems are designed to work at higher builds, they are usually the better choice if you're doing graphics or custom effects. Note that we said system here; these paints need to be used with the appropriate primers and clears. "The primer system we recommend when we build a skyscraper gives us max mechanical anchoring," observes Lynch. And just as you need the right material underneath all that paint, you need the correct clear over it. Refinish clear, applied liberally, measures around 3 mm; doubling that, according to Lynch, would be way out of spec. This can keep the clear from curing completely. Clear designed for use with custom paints creates a more stable film at high build-important when you're clearing over flames or graphics-and it provides the additional UV screeners needed to protect the exotic colorants used in custom colors. Both are critical to paint longevity. Whichever type of paint you decide to use, you have to use the proper supporting materials with it.

4 Things To Pay Attention To, From Jeff Matauch, PPG Training Center Instructor
Safety
"Whatever you use, there is no safe paint. Protect yourself by using a respirator, spray suit, and gloves, and always promote fresh airflow in your painting area."

Equipment
"Nine out of 10 times there's a problem, it's the equipment, and the first thing is always the compressor." You can buy a $600 paint gun, but if your compressor doesn't put out, it's all for naught. "A typical HVLP gun needs 15-18 cfm air pressure, and a compressor creates 3-4 cfm per horsepower. That means a 5hp compressor is borderline. The size of the air lines is critical-you should use 3/8-inch hose and high-flow air fittings for better volume. And air filters are a must.

Wrong Product For Job
You have to put the right type of solvent or reducer in your paint. "Anytime you use a solvent, you have to choose the correct grade based on the temperature you are spraying at." If you use a solvent that makes the paint dry too quickly, for instance, it can skin over, trapping solvents underneath. This can cause problems like dieback (dulling) or solvent pop (blisters). "You can go on our site and get a description and mixing directions for any of our product lines. It takes the guesswork out."

Waterborne Paint
Use of waterborne paint will be mandatory in parts of California starting this July. So what, you say? Well, as the Golden State goes on environmental issues, so goes the rest of the country, eventually. Some painters think it's the end of the world; most are at least concerned. "My confidence is high, and I'd have no problem spraying it now." Waterborne paint is more consistent and stable, since there are no solvents to settle out. "It's easier to spray, the metallic control is better, and it's more durable." And, of course, it's more user-friendly.

Adhesion & Cocktailing
It's a given that paint has to stick to the surface you're spraying it on, and when it doesn't, you've got problems, usually of the take-it-all-off-and-start-over type. "There are two ways that paint adheres," Prewitt explains. "One is physically; that's the reason you use different grit sandpapers. The other is chemically; the layers melt into each other. Acrylic lacquer won't take acrylic urethane clear. "It won't bond; it's like putting a piece of plastic on it." That's an extreme case, but if you start cocktailing back and forth with different materials, it's a crapshoot. And a lot of adhesion problems come from cocktailing, the mixing of different products from different manufacturers. The bottom line is that you need to stick to one manufacturer's product line throughout the job, ensuring compatibility. "I always recommend you follow the manufacturer recommendations, read the tech sheets, read the can. You know, most painters, the more experienced you get the less you think you have to read; I'm guilty of it."

Ironically, it's easier than ever to get this information-tech sheets are available online from both House of Kolor and PPG, among others. Prewitt boils this subject down nicely: "Between the chemical and the physical bonds, that's what really makes paint stick. You can't sand too smooth or it won't physically bond; you can't cocktail or it won't chemically bond. Knowing those two things can save a guy a lot of headaches."

Photo Gallery: 1968 Camaro Auto Body Repair - Structure & Color - Chevy High Performance

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]]>http://www.chevyhiperformance.com/tech/paint_body/0805chp_1968_camaro_auto_body_repair_structure_colorhttp://www.chevyhiperformance.com/tech/paint_body/0805chp_1968_camaro_auto_body_repair_structure_colorThu, 01 May 2008 00:05:00 -07001970 Chevelle Frontend Revival

Sometimes you own the project and sometimes, unfortunately, the project owns you. Case in point:The '70 Chevelle shown here started out as a potential grudge-night brawler, only to be abandoned after the funds ran dry. Prior to sitting on the sidelines, a freshened 502ci big-block was dropped in between the rails and the entire frontend was removed in anticipation of being upgraded with new sheetmetal. Suffice it to say, years down the road it still needed a face-lift-among other things.

These days, the once idle 'Velle is in capable hands of a new owner, and he has little intention of reviving the dragstrip theme. Instead, we're talking street thumper with the occasional open-track jaunts. Don't expect a trailer queen asking to be pampered with A/C. We're starting by giving the ol' ride a new look with fresh components right out of Year One's mail-order catalog.

If you want the honest truth on the difficulty factor...let's just say if you've never tried to align a fender, then you'll have to deal with a slight learning curve, but it's really a matter of playing with shims to properly fill the gaps. Yep, it's nothing a little patience can't handle. Other than that, the radiator core support, the fender extension, and the front bumper went on with little drama, but we'll get more into that. The one thing we highly recommend you order is a frontend fastener kit. For $59, it comes complete with black-oxide pinch bolts, cage nuts, fender washers, and detailed information of where each piece goes. Besides, you'll be hours ahead by not having to search for miscellaneous bolts.

In the months to come, we'll add larger binders on all four corners to help bring it to a stop, and we'll even address the suspension. That's right, nothing crazy. Just easy bolt-ons for a truly functional street machine. Follow along as we begin the first phase of changing a straight-edge drag piece into something a bit more civil for the street, with a hint of attitude.

Quick Notes
What We Used
Sheetmetal from the Year One catalog

Bottom Line
Easy weekend bolt-on with minimal handtools

Price (Approx)
$1,600

1. Body filler	$77
2. Sandpaper	$112
3. Tape and masking paper	$85
4. Primer	$171
5. Basecoat/stripes	$475
6. Clear	$125
7. Activators, catalysts, and reducers	$331
8. Respirator and spray suit	$90
9. Cleanup supplies	$53
Total	$1,519

>

THE GRAB BAG
ITEM	PN	COST
Front bumper	BF070	$257
Bumper bolts (8)	A8624	$28
Grille filler panel	MH698	$93
Bumper brackets	YD27	$154
Radiator core support	AJ649	$205
Frontend fastener kit	ID127	$59
Left/right fenders	JR46LHRH	$671
Left fender extension	YD84LH	$65
Right fender extension	YD84RH	$65
	Total	$1,597

Air springs are to suspension systems what vacuum-secondary carbs are to engines. Catch a glimpse of vacuum-secondaries under the hood of a hot rod and you'll automatically assume the motor's a turd. Real men want full throttle right now, baby, and dig carbs that hit hard! Never mind the fact that vacuum-secondary carbs can easily make as much peak horsepower as their similarly sized mechanical-secondary counterparts without sacrificing streetability. Likewise, witnessing a car that can alter its ride height at will elicits a similar knee-jerk response. Air suspension is for poseurs, not racers, so it has no place in your musclecar, right? Not if Air Ride Technologies has a say in the matter.

The company has developed a habit of making converts out of skeptics. Not just any skeptics, but pros who happen to be among the best road racers in the country. Air Ride enlists big-time racers such as Boris Said and Scott Pruett-two guys who race alongside the likes of Jeff Gordon and Tony Stewart-to test its products, and the feedback from the harshest critics around has been overwhelmingly positive. Common sense says that if it impresses them, it will probably impress you too. So how does it work, what are its benefits, how do you tune them, and how hard are they to install? We talked with Bret Voelkel to find out, and we quizzed him on other assorted suspension design topics as well.

Spring Rates
Whether a progressive-rate spring or a linear-rate spring is better for hard-core cornering is much debated, but there is a time and place for each. According to Bret, the only argument against using a progressive spring rate would come from the potential tuning headaches it creates for novices. "A progressive spring rate is just one more tuning variable to throw into the mix when it comes to overall suspension tuning, but if you have an adjustable suspension and the know-how, then that variable is easily manageable," he explains. When it comes to air springs, they can be made to be perfectly linear or extremely progressive. Air Ride typically uses double-convoluted air springs in the front suspension since it's highly leveraged. "This is because the front wheel always travels faster and longer than the air spring and shock, so we want the air spring to gain spring rate much quicker to properly control the oscillations of the vehicle. In the rear, we typically use a sleeve-style air spring with a nearly linear spring rate. Since the rear air spring is more of a direct load application that moves at the same rate as the axle and wheels, it needs more travel and a softer spring rate throughout its travel."

Components
"An air suspension is viewed as being more complex than a mechanical suspension, but in reality, the only additional part is the compressor system. The coil spring is replaced by an air spring, and you still need a shock absorber, just like in a traditional suspension. A compressor system can be as simple or as complex as the customer desires. A simple compressor system would consist of a compressor, a tank, air lines, and an inflate/deflate valve for each air spring. An automatic leveling system would add ride-height sensors and some sort of electronic controls to process the data generated by the leveling sensors. This is an area that has a lot of variables and could fill an entire article by itself."

Adjustability
"One of the biggest benefits of an air suspension system is the ability to quickly tune the chassis to prevailing track conditions. Theoretically, you could achieve the same performance from a mechanical spring as you could from an air spring if you had the necessary skill, patience, and equipment to properly tune the suspension. However, road conditions are only one factor to consider in a car that sees both street and track duty. If you change the load in the vehicle with passengers or luggage, you have to start all over with the tuning process. It takes a lot of perseverance to tune a suspension via the traditional method of changing components through trial and error. Therefore, people often end up living with some level of compromise in ride quality or cornering performance. An air spring gives the ability to make tuning changes much quicker and easier at the touch of a button, which often equates to less compromise."

Construction & Durability
Those unfamiliar with air springs may question their durability, but they're actually the spring of choice in applications far more demanding than any standard passenger car. "Since air suspension is somewhat new to the hot rod world, it is assumed that it is a new invention altogether," says Bret. "The truth is that more than 95 percent of all semitrucks use air springs-and have for over 25 years. Just like a tire, air springs are made from layers of fabric and rubber, and the weave of the fabric is a key element in determining the expansion characteristics and performance of the spring. Firestone's been making air springs for more than 70 years, and they manufacture springs for us to our specifications."

Shop Cars
"Air Ride has a total of 28 in-house project cars, and there are two simple reasons for having such an extensive collection. First, I feel the only way to develop a product is to have a car in front of you for an extended period of time. This means no customer-imposed deadlines, cost considerations, or squeamishness about hurting their car. Therefore, you must own the car. Furthermore, the development should not stop when the first system is shipped. We constantly evaluate and refine our products based on our experiences on the road and at the track. Since we are building the car anyway, we also take the opportunity to create installation tech and track-day articles and take photos for ads and various feature articles. It is a time-proven method of development, refinement, and promotion that we have copied from the pioneers of hot rodding and racing. The cars are much more a tool than a toy in these respects. The second reason for having so many cars in-house is that it's a great excuse to feed my personal hot rod habit. I love these cars because, as is the case for many of our customers, I grew up with them."

Air Leaks
One of the most common snafus of an air suspension install is air leaks, but fortunately, a few simple tricks can help you avoid them. If the air lines are cut cleanly and squarely, and thread sealer is used on the pipe fittings, leaks are actually quite rare. "To locate a leak, the old-fashioned method of spraying the connections with soapy water works best," explains Bret. More likely than not, the culprit will be at one of the connections. "I don't think I have ever seen an air spring itself leak. It's always a fitting that is left loose or has no sealer. DOT-approved fittings are a must as well, since they have a built-in insert that supports the inside of the plastic tubing to seal it better than standard fittings."

Four-Link Conversions
Air Ride's AirBar rear suspension system converts a factory leaf-spring suspension into a four-link. This begs the question: How is a four-link superior to conventional leaf springs? "A leaf spring is asked to perform several functions in the suspension," explains Bret. "In addition to holding the car up, it is expected to control the lateral, front-to-back, and pinion-angle movements of the rear axle. Obviously, trying to optimize all these functions ends up in compromise. By separating the job of suspending the car from the job of holding the axle in the car, we can optimize each job more easily."

Musclecar Handling
The straight-line machines of the musclecar era had some shortcomings in basic suspension design, and Air Ride works hard to correct these issues using modern technology. Bret says most OEM front suspension systems, especially those in GM vehicles, were designed to tilt the top of the tire outward when compressed. This resulted in understeer when driven to the extreme. "Their thinking was that in a panic situation, most drivers would instinctively go for the brakes, which, in a pushing situation would be the safe and correct action, but this design does not offer optimal handling," explains Bret. "Ideally, the top of the tire should tilt inward when compressed to maintain maximum tire contact when cornering, and we offer a taller spindle for several applications that improves this geometry. Likewise, the large, cushy pivot bushings commonly used in the '60s lead to lots of suspension slop. We use a firmer rubber or polyurethane bushing to maintain suspension integrity."

Drag Racing
For those with eclectic tastes, an unfortunate byproduct of a tight chassis that handles well is compromised grip at the dragstrip. With the extreme adjustability of an air suspension, however, you can have the best of both worlds. "Just like any other form of racing, setting up an air-suspended car for drag racing isn't much different from setting up a traditional suspension," says Bret. "I am not a drag racing expert, but in general, we try to set the car up as loose as possible without getting into wheelhop. Loosen the extension valving on the rear to allow the rear suspension to lift the car and plant its tires. Also, loosen the front extension valving to allow the front end to come up and transfer the weight to the rear while keeping in mind that some cars like a bit more preload in the right rear spring to plant that tire better."

Installation Tips
Although it takes the better part of a weekend, installing an air suspension is rather straight-forward. The only special tools you may need are an electric saw and a welder, and a digital angle finder will assist in setting up the pinion angle. "As with any customization, take your time by measuring three times and cutting once," he explains. "If you run into a problem or a question, please give us a call, since that is why you bought the stuff from us in the first place. I always advise customers to call a potential manufacturer with some trial questions before buying to determine the level of service they can expect after the sale. We have our installation instructions on our Web site so the customer can get a good idea of what he is in for before buying."

R&D
"Several criteria must be simultaneously considered when creating a suspension, such as safety, ride height, ground clearance, driveline angles, air spring height, shock length, tire clearance, and component interference. We start by making a general decision on highway ride height and then mock up an air spring at its intended ride height. This tells us if any modification will have to be made to fit the air spring into the car properly. From there, it's a matter of making those accommodations, building a control arm, clearancing a coil pocket, and making sure proper ground clearance, driveline angles, and tire clearances are maintained. After a first version of the suspension is built, we usually take a drive and decide if any revisions need to be made for better performance or to accommodate the manufacturing process. In all, a typical system takes 8 to 16 weeks from inception to shipping."

AirPod
One of the few drawbacks of air suspension systems has been the different plumbing and electrical connections necessary during installation. Consequently, a typical installation takes 10-15 hours, but Air Ride's new AirPod cuts that time down to 1-3 hours. The AirPod is essentially a combination of compressors, air lines, solenoids, electrical wires, and an air tank that have been integrated into a single assembly. "Since the AirPod comes prewired, preplumbed, and pretested, all the customer has to do is bolt it in with four bolts, plug in four air lines, and connect the power and ground," says Bret. "In comparison, a standard system requires making 17 plumbing connections. With compact dimensions of 20x12x9.5 inches, we made sure it will easily fit in the front of the trunk in nearly any car."

Track Tuning
Let's says you've taken the plunge on an air suspension and plan on taking your car to the track. Sure, it's almost infinitely adjustable, but how exactly do you tune the chassis to suit your driving style? "An air suspension is tuned just like any other suspension," explains Bret. "If the front pushes out first, you may have to soften the spring rate or shocks to get the car to take a set and bite. If the rear kicks out first, you may have to soften up the rear a bit to get it to roll over and bite. However, there are many variables in addition to spring rate and shock settings-such as tire pressure, alignment, and sway bar settings-and it simply takes time to figure out how to adjust each to optimize handling."

You must have cylinder pressure to make horsepower and torque. If a cylinder-or cylinders-isn't holding pressure when the spark plug fires, there's gonna be less power in the power stroke. Performance suffers, and more serious engine damage could be on the horizon. A traditional compression tester can tell you how much pressure is being created in each cylinder; comparing the numbers reveals much about an engine's condition. A leakdown tester, on the other hand, measures how much cylinder pressure is being lost-better yet, it reveals where this pressure is going, for a more detailed diagnosis.

While a compression tester measures the cylinder pressure created by the pumping action of the piston, a leakdown tester utilizes an outside air source to pressurize the cylinder. The less pressure being lost the better that cylinder is sealing. An engine in good shape will see a minimal drop-if it's seen some wear or has a serious problem, the drop will be greater. All cylinders will show some leakdown due to standard engine clearances and normal wear; the Proform unit shows up to 40 percent leakdown as within the "normal" range. It's more important that the reading be consistent-if one cylinder is out of line to the bad side, you know there's a problem.

And in any case, but especially when the readings fall into the "moderate" or "severe" range, it's vital to know where this pressure is going, and that's where a leakdown tester really shows its worth. The air being introduced into the cylinder escapes by any path available to it. By listening for this exiting air and noting its route, you can pinpoint problem areas in the engine.

That's what we did here. We ruled out the head gasket failure we feared but found moderate leakage past the rings. We now have a much better picture of this engine's condition-and can proceed accordingly.

Quick Notes
The job
A leakdown test on an '84 Z28

Bottom Line
We determined how much this engine is leaking, and where it's leaking from.

Price (APPROX)
$75

Possible Causes for High-to-Moderate Cylinder Leakage
The cause of low pressure can be determined by listening for escaping air.* Air escaping from crankcase breather, dipstick tube, or sump plug hole: Defective rings or worn cylinder walls

* Air escaping from carburetor: Defective intake valve

* Air escaping from exhaust system: Defective exhaust valve

* Air bubbles in radiator or air escaping from adjacent spark plug hole: Leaking head gasket or crack in block or head Courtesy of Proform

When you come right down to it, we have the same hopes for our classic Chevys' steel bodies as we do for our own flesh and bones. We want both to look good, and we want them to be disease- and injury-free. If something does go wrong, we hope the cure is minor: a pill, an ointment, maybe a little rubbing compound. Unfortunately, some maladies require major surgery to cure, and automotively speaking, rust is second only to catastrophic collision when it comes to bodily health. The bottom line is this: When rust has eaten all the way through a body panel, the only answer is to excise the affected area and replace it with new metal.

Of course, many areas affected by rust in our favorite musclecars are part of the structure, meaning old metal must be cut away and new metal welded into place. Add in the fact that these structures often consist of multiple layers of metal, and you're facing nothing short of reconstructive surgery. We joined the crew at Studio Auto Body as they rehabbed the lower rear quarter-panel area on an old A-body. The cancer here penetrated all the way through the outer fender and into the inner fender, so both pieces had to be replaced. Because the crew at Studio fabricated the necessary pieces instead of buying repro patch panels, this is a job that shouldn't be tackled by the faint of heart. Here's a taste of what it takes to graft in a piece of new, healthy metal.

Quick Notes
What We Did
Patched a rusted rear quarter-panel on a '69 Chevelle

Bottom Line
A well-done patch job restores a car's structure and appearance.

Cost (Approx)
Starts at $800

"Light makes right," the saying goes, and indeed, most guys who turn to fiberglass hoods are looking to rid their rides of a few extra pounds. There's nothing wrong with losing some weight, to be sure, but it's not the only reason for going with 'glass. These hoods are relatively easy to make, so they come in a variety of styles and cowl heights. We didn't want a huge cowl for our project '84 Z28, but we did need a bit of extra clearance, given that we'd installed a taller-than-stock intake manifold on the car's 305 (not to mention the nitrous plate we've got planned). And as we learned, the cowl arrangement also improves airflow through the engine bay, lowering engine temperature. We got on the horn to Year One and ordered up a 2-inch cowl induction fiberglass hood.

These hoods are available in both bolt-on and pin-on configurations, and we elected to go for the former. While this hood does indeed bolt on, we are talking fiberglass here, so some massaging is necessary to get the alignment just right. We headed over to Harrison Restorations, where head man Harrison Ortis and crew took the time to fit the new hood to our '84. If you recall, our car was hoodless after its last track excursion, but Ortis had an '87 IROC on hand for reference, and this proved invaluable when it came to creating a factorylike fit. The job may seem daunting, especially since there is some grinding to do, but it's mainly just a matter of working the extra-long edges of the hood until they match the factory contours. That's what Ortis did, and we ended up with a light, great-fitting hood that gives us the extra underhood clearance we were looking for. Check it out.

Quick Notes
The Job
Outfit a third-gen Camaro with a fiberglass cowl hood.

Bottom Line
A little time spent tailoring the lid to the car pays off with a first-class fit.

Cost (Approx)
$400

It's not enough to stuff a big-block in the engine bay of our project El Camino. No, we have to step it up a notch. To place such a work of reciprocating art into a dirty box just wouldn't be right. Under the hood is where the real showtakes place, where the engine will live. It just ain't right to open your hood and discover 40-plus years of dirt, road grime, oil residue, tar, and who knows what else-all cradling and enveloping superb muscle. It's like eating caviar with week-old pizza-the two just don't jibe.

The engine bay should be a shrine to all things powerful and fast-a Mecca and a foundation for making more power. It should embody the time and care you take with the rest of the car. People can tell a lot about a person by the way their engine bay looks. It expresses how serious you are about your project.

In our case, we spent the weekend with the Elco, washing, grinding, sanding, and finally painting the engine bay for this brute. We'll get you motivated to do the same and illustrate some of the pitfalls and tips that will make your endeavor a bit smoother.

Quick Notes
The Job
Degrease, sand, and paint away 42 years of grime.

Bottom Line
It's a cheap and easy weekend project.

Price (Approx)
$90

Warm Cans
There is a direct correlation between temperature and pressure. We placed the cans of paint in a bucket of very warm water for about 10 minutes. This allowed them to soak up the warmth of the water, which in turn builds more pressure. Think of it as a nitrous blanket for your paint can. No warm water? Just set them in the sun for a bit. Your quick warm-up will allow the paint to come out faster with more pressure, and it'll dry sooner.

PARTS & PRICES
ITEM	PN	PRICE
Scotch-Brite pads	N/A	$1.69
Rustoleum primer, automotive finish (3)	2089830	$9
Duplicolor high-heat, black (4)	DH 1602	$24
Oil Eater degreaser	AOD1G35437	$55
	Total	$89.69

At the heart of your powerplant is the crankshaft, and this baby not only has to endure the entire rotating mass, but it is subjected to countless spin cycles at varying rpm. It's a tough life, which makes proper installation that much more critical. It's nothing tricky, but taking the time to check tolerances can be the difference between a long -running powerhouse and a short-lived paperweight.

But what is it about bearing clearances that's so important? Simply put, if the main bearings are too tight, they'll burn up, and, conversely, if the clearances are excessively loose, you'll end up with a big drop in oil pressure at operating temperature. Let's not forget about the thrust tolerances. If you don't have enough crank endplay, you could burn the thrust up, which will eventually wear out the thrust on the crankshaft. If this should happen, you can expect to pony up some serious green for major reconstructive surgery, by having to reweld or even replace the crankshaft. All said and done, take the time to measure every journal on the crankshaft and each main bearing, and make sure to have your crank endplay in check.

The better it's matched the more you're freeing up available power. It's cheap insurance to know everything is working in unison and that the rotating assembly isn't fighting itself. We all know engines aren't cheap, so do it once, do it right the first time, and you won't have to worry about your mill giving up the ghost to a major catastrophe.

A couple of months ago, we rolled our '84 Z28 out of mothballs and put it in primer ("Primed and Ready," Mar. '07). This month, lest you think this particular Camaro is destined to be all show and no go, we're adding some go-fast parts to the mix.

You know the score: Third-gen Camaros are very affordable performance platforms. On the other hand, many of these cars--especially the early versions--need a lot of help in the power department. In a nutshell, that's where we're at with our subject. It's a challenging mission, since we're embarking on what many consider a fool's errand: extracting more power from our third-gen's original 305ci powerplant.

Why bother, you may ask. Despite its shortcomings, many of you want to see what we can do with the ugly duckling of Chevrolet's small-block lineup. Truth be told, we want to give it a shot too. These engines ended up in tens of thousands of cars from the mid-'70s through the early '90s. Plain odds dictate that some people will want to use a 305 for their performance build; many others will do it out of necessity, creating an engine piece by piece--sort of like what we're doing here.

Despite our Z28's haggard appearance, we've actually got a decent starting point. Our $1,000 eBay find came with an RPO L69, 190hp H.O. motor made available in '83-86 Camaros. In the performance wasteland that was the '80s, this engine was one of the more potent mills around. Ours was still in good shape. The car's odometer showed just shy of 75,000 miles when we got it, and after our friend Ralph Serrano at D&D Service rebuilt the untouched, computer-controlled Quadrajet, the thing was a decent little runner. Our baseline numbers, recorded on Primedia's Mustang chassis dyno, backed up our hunch. While 158 hp and 181 lb-ft of torque are well south of impressive, let's do the math. The L69 motor came rated at 190 hp at 4,800 rpm, along with 240 lb-ft at 3,200 rpm, both measured at the flywheel. Subtract 20 percent for driveline loss through our 700-R4 tranny, and we're right in the ball park.

That's the good news. The bad news is that our properly functioning, stock L69--fitted with factory-optional 3.73:1 gears and a set of BFGoodrich drag radials--could only propel our Z28 to a 16.59 quarter-mile, with a rip-roaring trap speed of 83.15 mph. OK, we know various magazines reported much faster test times back in the day, when these cars were new. It'd be hypocritical of us to say that you shouldn't believe what you read, so we'll just say that today, in 2007, our example was good for 16s. It was definitely time to get to work. Of course, here in California, we couldn't undertake this project without considering the smog police. We want our Z to be street legal, so it has to be able to pass the test. Put bluntly, our philosophy was this: Anything that can be seen on the car has to be legal for use in Cali and have the necessary EO (executive order) number to prove it. Anything that's not immediately visible, in our book, is fair game--as long as the car passes the sniffer test.

Our first stop was the Primedia Tech Center, where we began our quest for power by upgrading our Camaro's exhaust system with an Edelbrock after-cat system and TES headers, teamed with a Random Technologies Super Stainless catalytic converter. The improved flow provided by this setup netted us some nice power gains, but we also installed the new system in anticipation of what was to come: a set of Trick Flow's Small Chevy cylinder heads. We'll give you more details in the sidebar, but for now we'll point out that these lungs are made especially for 265-305ci engines and, best of all, they're smog legal. Trick Flow also hooked us up with a matching hydraulic flat-tappet cam. It's small, by the standards most of us are used to, but remember we're working with the smallish 3.736-inch 305 bore, and trying to keep the thing smog legal.

In the end, we came up with a real "good news, bad news" scenario. The good news is that our bolt-on barrage netted us gains of 53 hp and 45 lb-ft of torque, which lead to a 1.29-second drop in our quarter-mile time. The bad news is that our Z is still slow. But there's more good news: We haven't yet dialed in our subject's Q-jet to work with the new combo, and we've got some other ideas floating about, so there are certainly more gains to come. These are only the first ingredients added to a little Camaro concoction we're calling The Mulletov Cocktail, and so far, the mix looks good.

Small Chevy cylinder head airflow
(3.766-inch bore)
Lift (inch)	intake (cfm)	exhaust (cfm)
0.100	61	53
0.200	127	105
0.300	180	142
0.400	216	160
0.500	242	172
0.600	242	180

Performance Progression

Baseline

181 lb-ft @ 3,750 rpm

158 hp @ 5,070 rpm

Quarter-mile

60-ft: 2.47

1/8-mile: 10.63 @ 66.27 mph

1/4-mile: 16.59 @ 83.15 mph

Add after-cat and cat

192 lb-ft @ 3,600 rpm

166 hp @ 4,800 rpm

Add TES headers

198 lb-ft @ 3,700 rpm

175 hp @ 4,900 rpm

Add Trick Flow heads, cam, Performer intake, K&N filter

226 lb-ft @ 4,400 rpm

211 hp @ 5,150 rpm

Quarter-mile

60-ft: 2.273

1/8-mile: 9.884 @ 69.61 mph

1/4-mile: 15.40 @ 90.53 mph

Bolt-on Barrage Shopping List
MFG	Part Number	Description
ARP	134-3601	head bolts
	134-2001	intake manifold bolts
Edelbrock	5673	Cat-back exhaust system
	3701	Performer manifold (EGR)
	68743	TES Headers, Ti-Tech finish Four-bolt flange I-pipe, 3-inch diameter
K&N Filters	E-1450	Air filter
	HP-2002	oil filter
MSD Ignition	84111	Extreme Output distributor cap
	84101	Extreme Output Rotor
	31459	Super Conductor Wire Set
Random Technology	191-30002	catalytic converter, engine code G
Trick Flow Specialties	TFS-30300002	23-degree, 175cc Small Chevy Heads w/ 1.47-inch spring upgrade
	TFS-31400511	3/8-inch stud-mount roller rocker arm set
	TFS-31478500	Billet timing set
	TFS-21407850	chrome-moly pushords, 7.850 inches
	TFS-31400915	engine gasket set, pre `87
	TFS-K3140100	SBC cam and lifter kit (hydraulic flat tappet)

"Racing improves the breed," the old adage goes. But is change always for the good? That's what we set out to discover in this month's dyno thrash. In one corner, we had Dart's veteran Pro 1 aluminum cylinder head; in the other, we lined up the revamped version, the Pro 1 Platinum. The Platinum heads are the result of technology that Dart has been employing in its NHRA Pro Stock efforts, specifically a process known as wet flow technology. In short, a wet flow bench measures the flow of fuel and air--as opposed to just air--through a cylinder head. As a bonus, our 383 test mule was already wearing a set of Iron Eagle Platinum heads, so we threw them into the mix as well.

Wet Flow Basics
As you may have divined, the wet flow process allows a cylinder-head designer to look at how the air/fuel mixture behaves when routed through a head and into the combustion chamber. "We're not just looking at dry flow, we're looking at wet flow," says Dart's R&D manager, Tony McAfee. Given that an internal-combustion engine needs both air and fuel to perform, it makes perfect sense. As we've explained elsewhere, much of this process' advantage comes from being able to see how the air/fuel mixture actually behaves within a cylinder head and shape the ports accordingly. There are, however, other advantages.

"One thing I look at," says McAfee, "is whether a port design will maintain a constant air/fuel ratio." Tests are made at a predetermined ratio, 13.7:1. But the wet flow bench also measures the actual air (in cfm) and fuel (in pph) being used. "The air/fuel ratio with the most fuel makes the most power," McAfee tells us. Remember that the idea is to obtain a homogenous mix of air and fuel. "The fuel must be kept in suspension as much as possible," McAfee elaborates. With a better mix, more fuel is actually delivered to the combustion chamber, creating the potential for more power.

One other difference between a traditional dry flow bench and Dart's wet flow process is that the tests are made at 55 inches of water, rather than the 28-inch level we're all familiar with. "It's actually closer to the high-rpm depression (low pressure point in the cylinder) at WOT," McAfee explains. "Fifty inches is closer to a serious bracket engine, and a Pro Stock or Winston Cup engine is well over that. We need three 50hp engines to get there."

By the Numbers
Bottom line? The wet flow process has yielded a better-flowing head that makes more power. Period. The dry-flow figures show improvements in airflow, but the wet flow results really tell the tale. Take a look at the numbers. Considering airflow only, the old Pro 1 actually outflows the newer Platinum version in some areas. Add fuel, however, and the Platinum head is the clear winner, as shown in the airflow figures and as demonstrated on the dyno. We made a whopping 23.5 more horsepower, along with 10.7 extra lb-ft of torque, and interestingly, each peak occurred 300 rpm later than with the older Pro 1s. Average numbers also improved, however, checking in with an additional 9 hp and 9 lb-ft across the board.

One thing we didn't expect was the huge power difference between the Iron Eagle Platinum and the Pro 1 Platinum heads, which were both designed using the wet flow process. Then again, the iron heads didn't feature the valve-seat insert or any of the CNC bowl work found in the Pro 1 Platinum--or the original Pro 1, for that matter. The Iron Eagles made good power on our 383 mule, and they pack a lot of bang for the buck. But the benefits of the bowl work found in the aluminum heads were clearly demonstrated. Combined with the rest of this thoroughly revamped head, the results are striking. "It's a package," sums up Dart's McAfee. "No one thing alone can do it." Check out the numbers to see how the new wet flow-designed Pro 1 Platinums raise the performance bar.

Q&A WITH TONY MCAFEE OF DART MACHINERY
CHP: How did this redesign start, Tony? Tony McAfee: It was time to upgrade the Iron Eagle and Pro 1 heads, so what we did was take the old design and played with the wet flow process we've been using on our Pro Stock heads, looking to make a better mousetrap.

CHP: What are the advantages of the wet flow process? TM: You're simulating a running engine more closely than on a dry flow bench. An engine doesn't run just on air. When you add fuel, the whole airstream becomes heavier; it does much more than dry air.

CHP: Like what?TM: When you see the fuel run, it runs in streams. You see the vortices in the combustion chamber. And no matter what, fuel attaches to the port walls... It's gonna happen.

CHP: And you can actually see this on the wet flow bench? TM: Yes. It can be seen in black light, through a half port made of clear plastic. You can see everything the mixture does, where it's at, how it moves. We've been able to see many things we couldn't imagine.

CHP: So what have you learned so far? TM: The combustion chamber should be thought of as an extension of the intake port, and the way it's shaped can improve air/fuel distribution around the valve. The plug is also moved toward the exhaust port; it's now in the same place as a Vortec head. Flame travel is one of the big positive sides to a Vortec head. Most people think it's airflow, but that's only half of it.

CHP: What other areas have you found to be important? TM: The cross section of the port, for one. We've also worked on the short turn and the diameter of the throat. They need to be a specific area based on valve size. Also the bowl and valve-seat area. We want it to gather loose fuel, rather than let it hit just the back of the valve. Once it leaves the valves, you have to make the mixture keep moving.

CHP: Once you've seen how the air/fuel mixture acts on the wet flow bench, how do you go about achieving the results you're looking for?TM: It's trial and error, using traditional methods: epoxy, grinding, and welding. We do anything we can do to make it flow better. I'm still trying to teach myself how to influence the mixture flow.

CHP: Really? TM: Wet flow technology is in its infancy. I don't know half of 1 percent of what we'll know in a few years.

GOING WITH THE FLOW
Dry Flow (@ 28 inches of water)
	Pro 1 215		Pro 1 215 Platinum
Lift (inch)	Intake (cfm)	Exhaust (cfm)	Intake (cfm)	Exhaust (cfm)
0.200	128.0	114.8	144.1	107.0
0.300	184.1	142.8	191.1	139.6
0.400	230.5	165.8	228.2	166.4
0.500	260.0	178.8	258.1	185.1
0.600	260.0	186.3	265.3	195.6
0.700	260.9	191.3	268.2	199.9
Wet Flow (@ 55 inches of water)
	Pro 1 215		Pro 1 215 Platinum
Lift (inch)	Intake (cfm)	Fuel (lb/hr)	Intake (cfm)	Fuel (lb/hr)
0.200	165.6	58.3	174.0	58.9
0.300	230.8	79.3	228.6	78.8
0.400	276.3	94.4	278.6	95.4
0.500	308.4	106.4	312.6	111.9
0.600	328.9	113.7	331.2	113.9
0.700	324.8	112.4	329.5	111.1

383 STROKER SPECS
Displacement	384.6 ci
Bore x Stroke	4.040 x 3.750 inches
Rotating assembly	Speed-O-Motive cast crank and forged rods
Pistons	Mahle forged
Compression	10.30:1
Heads	Dart 215cc, 72cc chamber
Intake manifold	Dart single-plane
Carburetor	Holley 750-cfm Street HP
Distributor	Pertronix Flame-Thrower
Camshaft	Comp Cams hydraulic roller
Valve lift	0.520/0.540 inch, intake/exhaust
w/1.6 rockers	0.555/0.578 inch, intake/exhaust
Duration at 0.050	236/248 degrees, intake/exhaust
Intake centerline	108 degrees
Lobe separation	113 degrees

DYNO DETAILS
Headers	13/4-inch Hedman long-tubes with 18-inch extensions
Fuel	91-octane unleaded
Jetting	75 primaries, 80 secondaries
Timing	37 degrees
Iron Eagle Platinum
Max torque	464.2 lb-ft @ 4,600 rpm
Max power	463.9 hp @ 5,900 rpm
Average torque	425.4 lb-ft
Average power	335.8 hp
Pro 1
Max torque	473.1 lb-ft @ 4,700 rpm
Max power	479.7 hp @ 5,700 rpm
Average torque	432.3 lb-ft
Average power	342.2 hp
Pro 1 Platinum
Max torque	483.8 lb-ft @ 5,000 rpm
Max power	503.2 hp @ 6,000 rpm
Average torque	441.5 lb-ft
Average power	351.0 hp

Consider the camshaft. On the one hand, it's a simple thing, a stick with bumps on it. It sits above the crankshaft, linked to it by a timing chain, and spins at half the crankshaft's speed. The camshaft's rotary motion is converted, through a lifter, pushrod, and rocker arm, to linear motion. Voila, the valves open and the engine operates. If only it were that easy. The configuration of those bumps--more accurately referred to as lobes--defines the performance personality of an internal-combustion engine. By determining when an engine's valves will be open, and how long they will stay open, the camshaft determines how much power an engine will make. It also dictates where this power will be made throughout the engine's rpm range. And that's just for starters. The camshaft is often called the brains of the engine, and that brain determines what kind of powerplant you will have. In the next few pages, we'll give you the information you need to pick a camshaft that will create a powerplant you can live with.

What we can't do is give you a handy-dandy formula for choosing the right cam, because there isn't one. Camshaft selection depends on a host of variables. Engine displacement, compression ratio, type and size of cylinder heads, carb size (or are you running EFI?), and exhaust-system specs are all crucial to picking a cam that optimizes engine performance. But unless you're building an engine that will only see dyno duty, that's just the start. How much does your Chevy weigh? On top of that, transmission type, torque-converter stall speed, and rear gear ratio are all critical when it comes to choosing a camshaft. Accounting for all these variables could drive a gearhead nuts, yet it's something more basic that trips most of us up.

The first step in choosing a cam is, quite simply, honesty--brutal honesty. "Motor specifics are important, but so is setting out your purposes and realistic goals," says Lunati's James Humphrey. "The most common issue we see is that people don't think about where they're heading," chimes in Comp Cams engineer Billy Godbold. We all like to think we can make use of a car that makes 500 hp at 6,000 rpm, but is this really the case? Is the vehicle in question meant for bracket-race duty, or is it a Pro Touring creation for a cross-country trip? If it's a street/strip car, how much of its time will be spent on the strip and how much on the street? Or are you in the performance-street category, just looking for a bit more kick in your daily driver?

With intent in mind, take it a step further and ask yourself what your goals are. Do you need low-speed torque, or do you really need high-rpm power? Is idle quality important? Custom cam grinder Ed Curtis of FlowTech Industries sums it up better than we could. "You need the power where you're gonna drive it," Curtis tells us. "You want to give up the peak for a nice power curve." In other words, pick a cam that will put the power where you can use it.

Once armed with this information, you can go on to make a selection, but again, a little honesty goes a long way. "The biggest mistake we see is mismatched combinations," says Isky Racing Cams' Nolan Jamora. "Someone reads an article, and hears from a friend, and finds a manifold on sale... They think they have the best combo, but it doesn't work." This statement strikes to the heart of the issue. The camshaft is important, but the overall combination-including the camshaft--is even more important. Here's the good part: Every cam company we talked with wants to talk to you about your combo and picking the right cam for it. "There are too many resources for people to have to do this alone," declares Comp's Godbold. "Get advice," echoes Lunati's Humphrey. "You can't have too much information." We agree, and in that spirit, here's our camshaft primer.

How Long is too Long?
This is a subjective question, of course, based on the requirements for a specific combo and its intended usage. That being said, duration--the amount of time the valves are open--has a dramatic affect on engine performance. Stock camshafts usually offer relatively short duration and lift figures; for a small-block, we're talking less than 200 degrees duration at 0.050 and less than 0.450 inch lift, done in the interests of a smooth idle and optimal part-throttle response. What happens when we change this? Let's focus, for a moment, on the intake side. Longer intake duration opens the valve sooner in the cycle and closes it later. At lower engine speeds, this means the intake valve is still open as the piston begins to move upward, pushing fresh air/fuel mixture out of the cylinder. On top of that, cylinder pressure can't build until the intake valve closes. The result is an engine with poor low- and midrange response. But the late-closing intake valve becomes an advantage at higher engine speeds, when the higher air-inlet speeds keep filling the cylinders, even with the late-closing intake valve. In other words, increasing duration shifts an engine's torque curve higher in the rpm range. Choosing a performance cam becomes a big compromise; when it comes to power, you have to give some to get some. Each engine combo will work best with a particular amount of lift and duration, so the cam swapper's goal is to create that combination. Taking the conservative route with duration figures may not yield the most peak horsepower, but it will improve and maintain an engine's torque band, improving acceleration and throttle response across a wider rpm range.

Ramp It Up
Increasing valve lift allows more air/fuel mixture to enter the cylinders and more exhaust to exit, which generally leads to an increase in engine performance. Theoretically, doing this without increasing duration would create more power without altering the characteristics of the power curve. In reality, an increase in lift almost always leads to an increase in duration, because increasing lobe lift requires more distance to create the opening and closing ramps. And as we've noted elsewhere, more duration is not necessarily a good thing. This paradigm is being altered, however, by today's computer-designed, asymmetrical-profile cams. "Our asymmetrical cams have a high-acceleration opening ramp, while the closing side sets the valve down softly, helping longevity," says Isky's Jamora. "The idea is to have instant opening, dwell at the top, set it down." How is this accomplished? A cam's opening or closing ramp may look like it's a single section, but computer programs enable designers to get much more sophisticated. "With software, we can design a ramp with six or seven sections," observes Jamora.

Camp Cams' Godbold echoes these ideas. "Before, we had to make everything on the lobe faster," he tells us. "Now we look at every section of the lobe. We can be quick off the seat and create a lot of area under the curve. It makes a cam little and big at the same time." Crane had similar ideas in mind with its Z-cams. In addition to getting the valves open as quickly as possible, David Bly discusses Crane's goals when it comes to duration. "We want to keep our advertised duration number as small as possible, and our 0.050-inch duration figure as large as possible. The idea is to have a camshaft that 'acts' big but also improves low- and midrange power."

Open & Closed
A camshaft's function can actually be reduced to four points: intake opening (IO), intake closing (IC), exhaust opening (EO), and exhaust closing (EC). Intake closing is crucial, since it does the most to establish where peak torque occurs. An early IC improves low-speed torque, but limits high-rpm power since it also limits time for cylinder filling. On the other hand, a later IC allows more time for a cylinder to fill at high rpm but limits low-end torque, since cylinder pressure is pushed back through the intake port. Intake opening plays a big part in establishing overlap (when both intake and exhaust valves are open). An early IO increases overlap and can lead to a sluggish engine, since the intake charge is contaminated with exhaust gasses. A later IO reduces overlap, improves idle quality, and increases low-speed torque. Exhaust opening ranks second only to intake closing in affecting engine performance. An early EO can limit low- and midrange power by allowing torque-creating cylinder pressure to escape but help high-rpm performance by creating more time for exhaust gas to be expelled. Exhaust closing also affects overlap. An early EC reduces overlap. The time that both the intake and exhaust valves are open is reduced, improving idle but limiting midrange power. A late EC increases overlap, which hurts idle but helps high-rpm power. You'll find all these figures on a typical cam card, which can usually be downloaded from the manufacturers' Web sites before you buy. After that, it's all about deciding what characteristics you want your ride to have and choosing accordingly.

Take Your Pick
It's the lifter dilemma: Flat-tappet or roller, solid or hydraulic? All have their places in today's performance world, and price is often the deciding factor. Here's a quick rundown, with comparative price samples from Summit Racing.
* Hydraulic flat-tappet: This type of lifter is self-adjusting, thanks to a valve-controlled plunger inside its lifter body. Engine oil pressure maintains preload against the pushrod, and since no lash allowance is needed, they run quieter than mechanical lifters. On the other hand, they can perform poorly at high rpm due to an inability to bleed down excessive oil pressure. Plan on paying about $170 for a cam and lifters.
* Mechanical flat-tappet: This type of lifter is also called a solid, since that's essentially what it is--a solid link between the cam lob and the pushrod. They allow greater rpm potential, since bleed-down is not a concern, but do require that lash, or clearance, be set between the valve and rocker arm to allow for expansion as the engine gets hotter. You're looking at around $200 for a cam-and-lifter set.
* Mechanical roller-tappet: This type of tappet allows for the most-aggressive lobe designs, due to the roller follower, and lends itself to high-rpm operation, since it's a solid body design. Like its solid flat-tappet brother, it requires a lash setting that must be readjusted over time. A retrofit mechanical-roller cam-and-lifter kit costs about $550.
* Hydraulic roller-tappet: This type of tappet, used in OEM small-blocks since 1987, allows for aggressive lobe designs along with self-adjustability and quiet operation. They can, however, also suffer from bleed-down at high rpm. The tab jumps to almost $700 for a retrofit cam-and-lifter set.

One of a roller cam's greatest advantages is that rolling frictional forces are less than those caused by the "sliding" of a flat-tappet cam, which frees up some horsepower. In general, roller-tappet profiles can be more aggressive; in other words, more lift can be employed for a given duration. On the other hand, a flat-tappet cam actually accelerates the lifter more quickly in the initial portion of the lift curve. With a short-duration cam, a flat-tappet cam can actually get to a higher lift faster than a roller cam. Again, it all comes down to defining priorities and determining what will work best with your combo.

Degrees Of Seperation
A camshaft's lobe-separation angle (LSA) is ground into a cam and cannot be changed. Besides increasing or decreasing overlap, LSA has a variety of effects on how and where an engine makes power.
Narrower LSA	Wider LSA
Increased overlap	Reduced overlap
Increased low-rpm	Improved
torque	top-end power
Narrower powerband	Wider powerband
Reduced idle quality	Improved idle
	quality
Increased cranking	Reduced cranking
compression	compression
Decreased	Increased
piston-to-valve	piston-to-valve
clearance	clearance

BUZZ PHRASE: AREA UNDER THE CURVE
If you've indulged in any bit of camshaft research or bench racing, chances are you've heard the term "area under the curve." It's the Holy Grail of cam design, but what does it mean? The term itself describes what a valve-lift cycle would look like if plotted on a graph, with time in crank degrees running horizontally and valve lift in thousandths of an inch running vertically. The more quickly the valve opens and dwells in that position, the greater the space from opening to closing, or beneath the curve. The payoff, according to Comp's Godbold, is lots of high-lift duration without low-lift duration, making for better performance at all rpm.

ESSENTIAL CAMSHAFT TERMS
Centerlines
The intake centerline is the point of highest lift on the intake lobe, expressed in degrees after top dead center (ATDC). The exhaust centerline is that lobe's highest point of lift, expressed in degrees before top dead center (BTDC). The centerline is used to tie the valve timing to the crankshaft's rotation.

Duration
As lift refers to how far a valve opens, duration refers to how long it stays open. The opening time is expressed in degrees of crankshaft rotation, so a cam spec'd out at 230 degrees duration means the valve is being held open for 230 degrees of crankshaft rotation.
Cam makers usually refer to two types of duration:
* Advertised duration is the number of crankshaft degrees that the cam follower is lifted more than a predetermined amount off of its seat. The SAE standard is 0.006 inch. So advertised duration is the number of crankshaft degrees that the valve is open at least 0.006 inch. Not all manufacturers, however, use the SAE standard.
* Duration at 0.050 inch, on the other hand, measures the movement of the cam follower, in crankshaft degrees, from the point where it is first lifted 0.050 inch off the base circle on the opening side of the lobe to the point where it descends to 0.050 inch off the base circle on the closing side. This industry standard is especially valuable for comparing cams from different makers.
Lifter
A cam lifter, also known as a follower or a tappet, makes direct contact with the cam lobes and follows the contour, or profile, of the cam. We'll discuss this in greater detail later, but there are four types of lifters: hydraulic flat-tappet, solid flat-tappet, mechanical roller-tappet, and hydraulic roller-tappet.

Lobe lift
An eight-cylinder Chevy camshaft features 16 eccentrics, or lobes, that are based on a circle (thus its name, "base circle"). The height of the lobe above this radius constitutes the cam's lobe lift.

Lobe-Separation Angle (LSA)
This measurement indicates the angle, in camshaft degrees, between the maximum lift points on the intake lobe and the exhaust lobe. Lobe separation is usually calculated by adding the intake centerline and the exhaust centerline, then dividing by two. For example, a cam with a 106-degree intake centerline and a 114-degree exhaust centerline has an LSA of 110 degrees .

Overlap
Overlap is the amount of time, measured in crankshaft degrees, that both the intake valve and the exhaust valve are open. This situation happens at the end of the exhaust stroke and the beginning of the intake stroke. Increasing duration or decreasing lobe-separation angle--or doing both--increases overlap. A cam with an exhaust closing point of 4 degrees ATDC and an intake opening point of 8 degrees BTDC has 12 degrees of overlap.

single & dual
* Single pattern: In this type of cam, the intake and exhaust lobe profiles are identical, employing equal amounts of duration and lift. For example, a Comp Cams 270 Magnum (PN 12-211-2) cam has 270 degrees advertised duration, 224 degrees duration at 0.050 inch, and 0.470 inch lift on both the intake and exhaust sides.
* Dual pattern: This type of camshaft has different intake and exhaust profiles. In general, the exhaust lobe will employ more lift and duration to help evacuate exhaust gas from the cylinders. For example, Lunati Voodoo cam (PN 60130) has 261/267 degrees advertised duration (intake/ exhaust), 0.231/0.237 duration at 0.050, and 0.555/0.566 inch lift.

Valve Lift
This measurement refers to the distance, measured in thousandths of an inch, that the valve is lifted off its seat at the cam lobe's highest point. Remember, the cam's rotary motion is converted to linear motion through a lifter, pushrod, and finally a rocker arm. Therefore, valve lift equals lobe lift multiplied by the rocker-arm ratio. For example, if we have a lobe that measures 0.334 inch running a 1.5:1 rocker-arm ratio, 0.334 x 1.5 = 0.501 inch valve lift. Running a 1.6:1 rocker arm creates 0.534 inch valve lift.

Q&A WITH NOLAN JAMORA OF ISKY RACING CAMS
CHP: Isky is known as one of the real old-time hot rod outfits. That said, what's new?
Nolan Jamora: Isky still has its hot rod heritage, but in the last five years we've moved to the forefront of tech. CNC, Spintron, cam-design software--in order to stay current, you have invest in technology.

CHP: Where's most of Isky's business coming from these days?
NJ: I'd say 60 percent is hard-core racing and 40 percent is street, and three fourths of that is still traditional small-block and big-block applications. In the last year we've introduced 200 new grinds for the SBC, both hydraulic- and solid-roller. We're now on the LSX stuff.

CHP: What are you seeing in the LSX market?
NJ: Street/strip and drag is where we're seeing growth. There are blocks out there, and cars are coming out of warranty... There's potential.

CHP: What drove Isky to introduce all those new grinds for traditional small-blocks?
NJ: The availability of good-flowing heads and manifolds has never been better. Some of the out-of-the-box heads are fantastic. You need a cam that cam utilize that flow. You can't use a 15-year-old cam. It's the same with big-blocks.

CHP: What else has Isky been working on?
NJ: We found that we have to supply the whole package: lifters, springs, and pushrods. Things have to match. Doing one at a time creates a weak link.

CHP: What information would you like the public to know?
NJ: It's the combination that's important. If you improve your heads, you can go with more cam. But the best tip is to call us. Very rarely will a head guy know the combos, but a camshaft guy has to know what works.

CORE VALUES
In general, what the OEM does drives the aftermarket. One example of this is the increased cam-core diameter GM employs on the LSX engines. A 55mm core's advantages include its strength over traditional cams, and it is mainly used in more-extreme, high-horsepower drag-racing applications. The deflection under the torsional stress a camshaft incurs can actually change duration values--this happens less with the larger-diameter cam. But is also has a more functional benefit, according to Crane's David Bly. "The whole cam is scaled up, and it allows for more modern lobe profiles." Isky's Nolan Jamora agrees: "We get a constant stream of requests. It's part of the trickle-down effect from newer technology." The larger-core cams won't fit in a traditional small-block, but they will fit in aftermarket blocks. As these pieces become the basis for more builds, more of them will take advantage of the benefits of a 55mm core."

Q&A WITH ED CURTIS OF FLOWTECH INDUCTION
CHP: So, tell us about FlowTech Induction.
Ed Curtis: Most of what I concentrate my business on is working with select dealers that want a valvetrain and heads package.

CHP: And part of that is creating custom cams?
EC: If you call one of the big companies, you're not gonna get a tech who's the designer on the phone. That's where I come in.

CHP: How do you go about creating a custom cam?
EC: One thing is the term "custom cam." If it's in a catalog, it's not custom. The big companies are locked into their lobe designs. I'll go to whoever gives me what I want. Multiple vendors give me multiple choices, and most will also tweak things for me.

CHP: What are people looking for when they come to you for a custom cam or a package?
EC: People want everything. The Power Tour made a big impact, so they want the wheels, the suspension, and a 450hp motor that gets 20 mpg. I handle the valvetrain end of that.

CHP: Besides the multiple lobe choices, what makes your cams different?
EC: Many people only know what happens at 0.050. What I value is area under the curve, though that's an overused term.

CHP: What area makes up the bulk of your Chevy business?
EC: LSX packages are the top movers. The Gen I stuff, most people just pick up a book. They're not looking for that last 10-15 percent. But the high-end guy, the guy who spends $30-40K, does.

CHP: And that's where you come in?
EC: My grinds cost a bit more, though not a lot. I put in a little more time, and it works. It's amazing how many people want a source, and I can work with them one on one to give them a true custom cam.

We talked with Chris Richards of Mass-Flo EFI and checked out his latest advancements in fuel injection, which promise to finally bring simplicity intothe mix. He claims to have developed the world's only true plug-and-play fuel-injection system, and having raised our curiosities, he further claims the system requires no tuning or programming and that its installation can be done without any unnecessary hassles.

Unlike most aftermarket speed-density systems currently available, Mass-Flo is based on a mass-air engine-management system, which has proven to be both durable and reliable while offering ample performance. The heart of the Mass-Flo system is the revolutionary mass airflow meter (MAF) which resides atop the Mass-Flo 1,000-cfm throttle body. The MAF accurately measures the amount of air entering the engine, and the air/fuel ratio is adjusted accordingly to compensate for the load and variances in engine temperature, air temperature, and atmospheric pressure by reading values from the sensors included in the system. When you decide to upgrade your engine, drop in a new set of performance heads, change the bumpstick, or install a larger exhaust, Mass-Flo adapts to those changes by simply measuring the air required by the engine. That means no hassle or having to use a laptop. How cool is that?

For this particular piece, we watched over the shoulder of veteran racer and car builder Jack Rosen as he swapped over to the newfangled technology. The install is the same for any conventional Chevy small-block, and it's a breeze, only requiring a few afternoons to complete. And if you get yourself into a bind or prefer to have it installed by a pro, Mass-Flo has a list of authorized installers throughout the country.

During the installation there were no noted problems, and getting the system up and running was pretty smooth. If you're still hesitant about EFI, follow along as we detail the install from start to finish. Trust us, Mass-Flo will turn you into a convert, and you'll be glad it did.

HOW IT WORKS
Any naturally aspirated engine, regardless of brand, size, or combination of parts, requires a given air/fuel ratio at a given load. These ratios do not change from engine to engine, until you get into forced-induction applications. (We'll get to that later.) The needed air/fuel ratio changes with such things as engine temperature, air temperature, and atmospheric pressure, and the changes are the same for all engines. The task for any management system is to add the correct amount of fuel to the air the engine uses. Carburetors do it mechanically, so accuracy is limited. Speed-density systems do it by comparing the readings from various sensors to tables within the engine controller to determine the amount of air the engine is using. This actually works very well, if the values in the tables are correct, and therein lies the challenge. A professional tuner is required to enter the correct values into all of those cells in all of those tables. The next step is to drive the vehicle in the real world and adjust those values to tune out all the drivability issues. The other problem is speed density's limited ability to self-adjust, so your laptop must permanently reside in the passenger seat.

Worse than that, nonprogrammable or preprogrammed speed-density systems arrive at your door pretuned at the manufacturer on a dyno with a predetermined combination of parts on a specific engine. Well, with these systems, you can't fix them. And if you want to make a change to your engine, you can't adjust for it.

Mass-Flo does it differently. The MAF meter can measure the amount of air entering your engine, and again, if you know how much air the engine is using, then you just add the correct amount of fuel. It's that simple. The air/fuel ratio is adjusted accordingly to compensate for the load and variances in engine temperature, air temperature, and atmospheric pressure by reading values from the sensors. If you decide to upgrade your engine, Mass-Flo adapts to those changes. Remember, an engine is just a big air pump, and changing heads, camshafts, intakes, exhaust systems, and displacement are just ways of making your air pump more efficient (use more air). With speed density, it's back to the dyno to start all over again.

Speed density relies heavily on the signal from the MAP sensor to determine how much fuel to add. So what happens when your camshaft produces poor vacuum? You guessed it, horrible driveability. The Mass-Flo does not use a MAP sensor, and you can use any camshaft you want with the system. Pretty trick.

In forced-induction applications, the ratios are different, and a different tune is needed. Mass-Flo has a tune to cover those applications and can be adapted just about anywhere. If you want something custom, just ask. The company can do dual-quads and other applications where two MAF meters are required. In all cases, no tuning is ever required by the customer.

Q&A WITH CHRIS RICHARDS OF MASS-FLO EFI
CHP: Can the end user expect to see any significant increase in fuel economy by using Mass-Flo?
Chris Richards: That's a good question, and a tough one to answer accurately, especially since every engine combination will vary. What we can tell you is this: You are almost assured of an improvement. We've sold systems to customers who were previously using other brands of aftermarket fuel injection and saw large gains in economy (as much as 25 percent), as well as gains in drivability and power. Even more over a carburetor. Some customers have reported more than a 75-percent increased fuel mileage over their carbureted setup. We routinely hear of figures in the area of 21-25 mpg on engines making well over 500 hp!

CHP: How about emissions? Will I pass?
CR: Another tough one. Whether or not you pass will be determined by your combination of engine components. No induction/ management system can make an absolute fire-breathing gas hog pass emissions. However, we have never had a customer fail emissions, including engines that maybe should have failed. What we can say is that the Mass-Flo system will make it as clean as possible, and if there is a chance, the Mass-Flo system is your best shot.CHP: How much horsepower will the Mass-Flo system support?CR: We have used it with great success with engines producing as much as 1,000 hp.

CHP: I don't have much hood clearance. Will the Mass-Flo system fit?
CR: The Mass-Flo system will fit anywhere a conventional 4-bbl carb and intake manifold will fit. In many cases, it can go where a carburetor won't fit. Our throttle body is 11/4 inches lower than a typical 4-bbl carburetor.

IT'S ALL INSIDE
One call does it all! The kit for the small-block Chevy includes:

* Intake manifold
* 1,000-cfm 4-bbl throttle body w/idle-control motor and throttle position sensor
* 9/16-inch-diameter fuel rails w/ mounting assembly
* Mass-Flo ultracompact high- flow MAF
* Complete stand-alone wiring harness
* ECU
* Choice of 19-, 24-, 30-, 36-, or 42-lb/hr flow injectors (larger sizes available)
* All required sensors
* High-performance coil w/heat sink and mounting bracket
* All assorted hardware and fittings necessary for system installation
* Detailed installation instructions

The wind, dust, and rain all have their place in the world, but not inside your car. To isolate you and your car's interior from these elements, the doors, trunk lid, and window glass are factory-fitted with precision-molded weatherstrips that work to form a moveable seal against glass and metal objects. But after a million times opening and closing your doors combined with a couple of decades of summer sun and winter freeze, those once-pristine factory seals and weatherstrips have probably deteriorated, fallen apart, or dried out. The answer is simple: Replace those worn rubber weatherstrips with new ones--installed properly.

Replacing the soft rubber is generally straightforward. The best time to remove the old stuff is right before the car is painted, and the best time to install the new stuff is about a month after the new paint has been sprayed, cured, and buffed. This way you'll have a cleaner installation without overspray on the new seals. If you won't be painting your car, the weatherstrips can still be replaced successfully. Just use caution, and with careful workmanship, the soft parts can typically be replaced without damaging the existing paint job. Don't fret over the tools needed to complete this resto bit; all that's required are a few basic hand tools, and it can easily be handled out of your garage in a matter of hours.

To make the car quiet and leak-free and to give it a newer-car feel again, we chose seals and weatherstripping from Soffseal and National Parts Depot. If you're wondering about the cost, expect anywhere from $3 up to $500 if you need to replace most of the seals. For a complete breakdown of part numbers and prices to outfit our 'Bu, log on to chevyhiperformance.com; otherwise follow along as we show you the easiest and best way to get the job done.

Here's the scenario: You're looking to make big power, so you're looking to build a big-block. Sure, you can make plenty of ponies with a small-block, but it's hard to match the brute force provided by sheer cubic inches. When the first "Mystery Motor"-powered Chevrolet won the 1963 Daytona 500, an undeniable big-block mystique was created. More than 40 years later, that aura of all-out performance is as strong as ever. So you want a big-block. You know how much money you have, and you want to get as much performance as possible for your dough. What are your options? Is the 454 still a viable performer, or is bigger--as in 496 or 540--always better?

Size Matters
That's the question we first set out to answer: 454 versus 496 versus 540? We planned to look at the power potential and price of this trio. Our exploration of the big-block world, however, quickly led us in a slightly different direction. There are plenty of 454-powered vehicles still making the scene, but they're becoming the exception rather than the rule when it comes to performance builds. Stroker rotating assemblies, we learned, cost nearly the same as a stock setup, making them more cost effective. If it costs the same to build a 496 or a 506, then why not do it and make more power while you're at it?

The "bigger is better" ethos doesn't stop there. For many builders, especially those beginning from scratch, the increasingly affordable price of aftermarket blocks makes 540 ci the displacement starting point. "People want the biggest and baddest engine they can get," we were told, and whether they buy it all at once in crate form or in pieces over time, that's what the aftermarket is giving them. Whereas 500 hp was once a respectable number, 600 seems to be the new minimum.

Mathematical Gymnastics
In fairly simple mathematical terms, the quest for more displacement is logical. More displacement means more power, but you knew that, right? In general, a properly tuned production automotive engine produces 1.0-1.5 hp per cubic inch. Where a particular engine falls depends on many factors, so we'll use 1.3 hp per cubic inch as a middle figure. That means a 454 can support almost 600 hp (454 x 1.3 = 590.2). Indeed, many do. Using the same multiplier, a 496 can support 645 hp. And remember, the price difference between the two is minute. We're sure you see where this is heading. So we ask, how much does it cost to build a 454 that can support 600 hp, as opposed to the cost of a 540, which can support more that 700 hp?

Exploring the Big Country
By way of examining this issue, we set out to take a big-block cross section of sorts. We talked to a number of engine builders and parts suppliers, and we pretty much asked the same questions: What's your best bang-for-the-buck package? What are people actually buying? And, perhaps most importantly, we asked our industry sources for the bottom line, in other words, "What is the price of power?"

Of course, we also wanted to get an idea of what kind of power various big-blocks actually make, so we rifled the dyno-pull files at Westech for a few examples. It may not be exactly scientific, but it is grist for the mill. Let the bench racing begin.

HEADS UP
If we learned anything from our Rat-motor reconnaissance, it's that big-block Chevy heads ain't cheap. Some may cost only a few hundred dollars more (apiece) than their small-block counterparts, but many cost half as much again--or more. Anecdotal testimony came from our expert sources, almost all of whom sell plenty of short-blocks to customers who already have cylinder heads. With this in mind, we sought the voice--or rather voices--of experience, namely our friend Steve Brul of Westech Performance and our new friend, Harold Bettis of SuperFlow Technologies. Here's what our experts had to say.

CHP: All right, guys, what's your take on the oval-port versus rectangular port deal?
Steve Brul: The current thinking is that the oval shape is better than a rectangular port, as shown in current Pro Stock technology.
Harold Bettis: An oval-port head leaves fewer opportunities for eddies and irregularities of flow in the corners, because there are no corners.

CHP: So oval ports are better?
SB: Generally, with traditional-style oval-and rectangular-port heads, the smallest port with the highest flow volume is best.
HB: Yes, proper flow numbers are more important than size. Think of the air as a concentration of energy. If that concentration is high, it's easier to get air into the cylinders and harder to get it out (reversion).

CHP: So how does that relate to port shape?
SB: You should refer to oval and rectangular ports as a function of size, not of shape.
HB: At power levels over 550 hp, a rectangular port is the normal trend. When the volume changes to meet this level, it's easier to get the needed flow from a rectangular-port head.
SB:HB: Remember, an engine does most of its work and spends most of its time at part throttle, an