Chevy 355 Small Block Engine Build - Cheap Skate!
Using 30-Year-Old Recycled Parts, This 355 Kicks Out 467 Hp On Chump Change
From the December, 2008 issue of Chevy High Performance
By Stephen Kim
Photography by Stephen Kim
There's a sweet spot in the horsepower-per-dollar equation, and this 355 has its coordinates firmly locked onto that juicy territory. Scoff, if you will, at its mediocre 467hp output, but printing a big number on the dyno sheet with utter disregard for fiscal responsibility isn't what this motor's about.
With the caliber of cylinder heads, stroker rotating assemblies, and valvetrain components on the market today, cracking 550 hp with a small-block is cake. Eclipsing the 600hp mark requires just a smidgen more effort. However, with those incremental gains in power comes an alarmingly disproportional hit to the checkbook. While this 355 was built for less than $4,000, a 550hp Mouse could easily cost twice as much. Sure, speed costs money, but what if you don't have the greenbacks to play with the big boys?
Enter Terry Shallington's low-buck 355. Like most working stiffs, Terry had a real-world budget, which meant that spending $10,000 on a motor was out of the question. The formula for the buildup was quite simple: Buy what you can afford, even if it means leaving some power on the table. The final product is a ridiculously simple 355 mill that utilizes a factory four-bolt block, a stock GM steel crank, Eagle I-beam rods, forged Speed-Pro pistons, World Products iron heads, and a 255/263-at-0.050 Comp solid flat tappet cam. With a price tag right at $4,000, the 355's 467hp output works out at roughly $8 per horse.
Assuming for the sake of argument that a 625hp small-block would ring up a $10,000 tab, the math works out to $16 per horse. In other words, that would be 100 percent more money for just 22 percent more power. Like we said, this 355's objective is finding the sweet spot-and gloriously exploiting it.
From Attic To Dyno
In an interesting backstory to this engine buildup, some of the antique parts came straight out of the attic. Terry is the original owner of an all-original '69 Z/28, and after the factory 302 went poof! decades ago, he went on an extended hiatus from drag racing. Now that the kids are all grown up, he's hitting the local bracket racing scene again and is even considering competing in Stock Eliminator. Before that could happen, he enlisted the help of the School of Automotive Machinists in Houston to build a durable powerplant. Most of the components are new, but to help keep costs down, Terry dug up some 30-year-old parts from his street racing days. Not only are the battle-proven Crane roller rockers, Victor Jr. intake, stock Z/28 carb, and Stahl headers interesting pieces of nostalgia, but they still perform exceptionally well by today's standards.
A stupid-easy pump-gas 355 bracket motor
Nothing fancy here, just an $8-per-horse formula
A large cost-savings comes...
A large cost-savings comes from our swapmeet finds: a four-bolt block and a factory steel crank. After cutting the journals 0.020/0.020 and align-honing the block, the crank was ready to drop in. A benefit of a stock-stroke crank is the reduced labor costs when balancing the rotating assembly, which required simply removing a wee bit of material from the front counterweight. Since the motor won't see much past 7,000 rpm, main studs are not necessary.
The 5140 Eagle steel rods...
The 5140 Eagle steel rods measure 5.700 inches and 565 grams. Eagle's H-beams would have been preferable in a heavier-duty application, but they would add mass and dollars. Furthermore, the I-beams are plenty stout considering the 355's relatively moderate rpm range and power output.
At only a few bucks over a...
At only a few bucks over a set of hypereutectic pistons, these Speed-Pro forgings are a raging bargain. They feature ribbed skirts for improved oil retention and a Duroshield coating for reduced friction. A testament to the overall simplicity of the motor, the ring grooves accommodate an OE-like 5/64-, 5/64-, 3/16-inch ring pack. Although it comes with a weight penalty, using short rods also comes with the benefit of the piston's thick, 1.56-inch compression height, should they ever encounter nitrous.
To ensure pump-gas compatibility...
To ensure pump-gas compatibility with the motor's 10.5:1 compression, quench was optimized with a 0.040-inch-thick head gasket and by zero-decking the block.
The cam's 255 degrees of duration...
The cam's 255 degrees of duration combined with a large, 2.08-inch intake valve resulted in minor piston-to-valve contact, which required slightly enlarging the intake valve reliefs.
GM engineers missed the mark...
GM engineers missed the mark in the '60s but were on the right track. The factory Z/28 oil pan featured a windage tray,...
...but its effectiveness was...
...but its effectiveness was marginal to nonexistent. The baffles in the 7-quart Moroso pan used on the 355 perform far better.
The Comp solid flat tappet...
The Comp solid flat tappet cam measures 255/263 at 0.050. Since the flat tappets limit lift to 0.540/0.534 inch, the School of Automotive Machinists (SAM) says a solid roller cam with similar duration figures would yield an additional 15-20 hp. However, the flat tappets are less expensive and provide excellent durability. To keep rpm from exceeding 7,000 with a budget short-block, the lobes were ground on a relatively tight 106-degree LSA.
Getting the job done up top...
Getting the job done up top is a set of World Products 220cc iron heads. They feature 2.08/1.60-inch valves and can support upwards of 500 hp.
After a quick fluff-and-buff...
After a quick fluff-and-buff job that involved gasket-matching the ports and radiusing the bowls, SAM coaxed an impressive 280 cfm out of the intake ports. Despite their large cross-section, the ports maintain excellent low- and midlift velocity, as proven by the 355's average torque output of nearly 400 lb-ft.
On the exhaust side, minor...
On the exhaust side, minor massaging bumped flow to 220 cfm.
The World Products heads come...
The World Products heads come fully assembled with beefy 1.55-inch springs compatible with solid lifter cams.
The 62cc combustion chambers...
The 62cc combustion chambers boast an extremely large quench pad. Its effectiveness is evidenced by the fact that the 355 required just 35 degrees of ignition advance despite relying on iron head castings.
What did Victor Jr. intakes...
What did Victor Jr. intakes look like back in 1969? A lot like this. The relic was gasket-matched and still proved plenty capable of supporting the flow demands from today's cylinder heads.
On the dyno, maximum power...
On the dyno, maximum power was achieved with a 1-inch open-plenum phenolic carb spacer.
What was considered trick...
What was considered trick technology back in the '60s is the norm nowadays, but these 1.5:1 Crane roller rockers still perform flawlessly after sitting in an attic for more than 30 years.
Original DZ-style Z/28 carburetors...
Original DZ-style Z/28 carburetors such as this one fetch $1,000 on eBay. It makes you wonder how many are actually still in use at the track. We now know of at least one.
|The Recipe |
Since you probably don't have a bunch of 30-year-old parts lying around for your next engine build, we admit that your price for this 355 could be a bit higher. To calculate your probable cost to replicate this combination, substitute modern-day equivalents of the recycled parts used in this build. By tacking on $180 for a set of Crane Energizer rockers (PN 11744-16), $200 for an Edelbrock Victor Jr. intake (PN 2975), and $340 for a Holley 650 double-pumper (PN 0-4777C), your cost to duplicate this 355 could come to $4,651. Either way, it's still dirt-cheap.
|MFG ||ITEM ||PN ||PRICE |
|ARP ||Head bolts ||134-3601 ||$60 |
|Clevite ||Main bearings ||MS909P ||24 |
| ||Rod bearings ||CB663H ||24 |
| ||Cam bearings ||SH2905 ||18 |
|Cloyes ||Timing chain ||9-1100 ||32 |
|Cometic ||Head gaskets ||C5877-040 ||86 |
|Comp Cams ||Camshaft ||Custom ||166 |
| ||Lifters ||833-16 ||90 |
| ||Pushrods ||7993-16 ||130 |
|Crane ||Rockers ||N/A ||0 |
|Eagle ||Connecting rods ||5700BPLW ||236 |
|Edelbrock ||Intake manifold ||N/A ||0 |
|Fel-Pro ||Intake gasket ||1405 ||19 |
| ||Oil pan gasket ||1818 ||15 |
|Melling ||Oil pump ||M55HV ||28 |
|Moroso ||Oil pan ||20191 ||196 |
|Professional Products ||Harmonic balancer ||8000 ||40 |
|Proform ||Timing cover ||66666 ||60 |
|Speed-Pro ||Pistons ||L2256F30 ||280 |
| ||Rings ||R9343.035 ||116 |
|World Products ||Heads ||014150-3 ||1,171 |
|Factory ||Block ||N/A ||50 |
| ||Production steel crank ||N/A ||100 |
| ||Z/28 carburetor ||N/A ||On hand |
| ||Parts Total || ||$2,941 |
|MACHINE WORK BY SAM |
|OPERATION ||PRICE ||OPERATION ||PRICE |
|Bore/hone ||$225 ||Deck resurface ||$100 |
|Align hone ||125 ||Balancing ||75 |
|Turn crank ||65 ||Head/intake porting ||400 |
| ||Machine Work Total || ||$990 |
| ||GRAND TOTAL || ||$3,931 |
|BUILD SHEET |
|All measurements are given in inches unless otherwise noted. |
|Block ||Junkyard GM four-bolt |
|Bore x Stroke ||4.030 x 3.480 |
|Displacement ||355 ci |
|Rod length ||5.700 |
|Deck height ||0 |
|Head gasket thickness ||0.040 |
|Main bearing clearance ||0.0023-0.0026 |
|Rod bearing clearance ||0.0020-0.0024 |
|Piston-to-wall clearance ||0.004 |
|Piston dome volume ||-6.1 cc |
|Piston compression height ||1.56 |
|Top ring gap ||0.017 |
|Second ring gap ||0.025 |
|Compression ratio ||10.5:1 |
|Camshaft ||255/263 at 0.050; 0.540/0.534; 106 LSA |
|Installed centerline ||102 degrees |
|Rocker ratio ||1.5:1 |
|Valves ||2.08/1.60, intake/exhaust |
|Valvespring diameter ||1.55 |
|Valvespring seat pressure ||135 pounds |
|Valvespring open pressure ||360 pounds |
|Carburetor ||Factory Z/28 DZ |
|Fuel ||93-octane unleaded |
|Ignition advance ||35 degrees |
|DYNO DATA |
|RPM ||LB-FT ||HP |
|4,000 ||378 ||288 |
|4,100 ||378 ||294 |
|4,200 ||378 ||303 |
|4,300 ||407 ||333 |
|4,400 ||414 ||347 |
|4,500 ||417 ||357 |
|4,600 ||421 ||369 |
|4,700 ||424 ||380 |
|4,800 ||426 ||390 |
|4,900 ||428 ||400 |
|5,000 ||429 ||409 |
|5,100 ||428 ||416 |
|5,200 ||425 ||421 |
|5,300 ||422 ||425 |
|5,400 ||418 ||430 |
|5,500 ||416 ||435 |
|5,600 ||413 ||441 |
|5,700 ||411 ||446 |
|5,800 ||408 ||450 |
|5,900 ||404 ||454 |
|6,000 ||401 ||458 |
|6,100 ||397 ||461 |
|6,200 ||393 ||464 |
|6,300 ||389 ||467 |
|6,400 ||383 ||467 |
|6,500 ||375 ||464 |
|6,600 ||366 ||460 |
|6,700 ||358 ||457 |
|6,800 ||351 ||454 |
|6,900 ||346 ||454 |
|7,000 ||341 ||454 |
|AVG ||398 ||414 |
|Automotive Racing Products (ARP)|
|Eagle Specialty Products|
|Holley Performance Products|
|School of Automotive Machinists|