Often the hunt for horsepower starts with a question. You know the type: "Hey, I made 480 hp-how much more would I have to do to make 500?" That's exactly the query posed by Jeff Latimer of Valencia, California's JGM Performance Engineering, who had a good combo in hand: a small-block throwing down 420 lb-ft of torque to go with all those ponies. What makes the question compelling, though, is that those numbers came from a "mere" 327. So when we learned that JGM had teamed up with its neighbors at Air Flow Research to deliver an impressive reply to the 500hp question, we didn't have to be asked twice to check out the results.

Latimer is a staunch 327 fan. "It's part of my memory from the good ol' days of Pro Stock," he told us. "Everybody was running them." So later on down the road, he built one: a 10:1, hydraulic flat tappet motor with duration at 0.050 in the 240s, and wearing AFR 180 Eliminator heads. No question, he was impressed with the result. They're great numbers for a 327-but you know where this is heading.

The foundation was another 327 block. When outfitted with ARP studs, the factory two-bolt mains were more than sufficient for the planned power level. The mains were also precisely line-honed and the bearing clearances set with the factory steel crank being utilized. The holes were bored 0.040 over; with the standard 3.250-inch stroke in place, displacement came out at 333 ci. The reciprocating assembly was fairly pedestrian: Eagle 6-inch I-beam rods topped with KB hypereutectic slugs. "They're enough for 500 hp," Latimer explained. The short-block is more than adequate, but nothing exotic, as our builder puts it.

The wealth of experience at JGM, along with some computer modeling based on cylinder head flow data and estimated cranking compression, led to more particulars. The chosen cam was an aggressive Comp solid-roller, boosted with Comp 1.6:1 Hi-Tech stainless steel rocker arms. Also of note is the piston deck height-the +0.005 figure, when combined with the cylinder heads' 60cc chamber volume, creates a fairly tight quench figure of 0.035 inch, which promotes efficient combustion.

Latimer was impressed by the performance of the 180 Eliminator heads on his first 327, and he naturally turned to Tony Mamo and the AFR crew for help in answering the 500hp question. The heads of choice were a set of the company's 195 Competition Ported Eliminators. Mamo put it in a nutshell: "Jeff and I felt these heads were ideally suited to this project, 'cause we intended to turn it pretty hard."

"Ideally suited," indeed: The horsepower goal was blown away by a good 10 percent, as in 50-plus more horsepower than the goal. Peak power came at a not totally astronomical 7,100 rpm. And as impressive as 553 hp is from a 327, check out the torque numbers. Right off the bat, 433 lb-ft at 5,600 isn't a bad peak. But this thing's at 380 lb-ft by 3,900 rpm, and stays over 400 from 4,600 all the way to 7,200 rpm. It's a screamer-but one with an impressive and flat, useable torque band. "That's why we used the 195 Comp ported heads," reiterated Mamo. "Since this engine will spend more time on the street than at the track, we were concerned about the bottom end and throttle response as well as the top end power."

Latimer is thrilled with the results, especially, we suspect, with that flat torque curve, since this mill could find a home in the '63 Chevy II he's been working on. On the other hand, more questions have already arisen, and Latimer admits that he might have used some different components if he'd known he was going to exceed the 500hp goal by so much. He's already working on it, and of course the question has already been posed: "I wonder how much more it'll make next time?"

Quick Notes
What We Did
Followed along on a mission to obtain 500 hp from a 327 small-block

Bottom Line
Mission accomplished-and with a 53-horse bonus

Cost (APPROX)
$9,500

  • 327 Small Block Chevy Engine Build Gm Hei Distributor
    Ignition duties were handled by a standard GM HEI distributor, suitably enhanced with an MSD Digital HEI Module and Coil. The setup handled 7,500-plus rpm without any issues.
    Ignition duties were handled by a standard GM HEI distributor, suitably enhanced with an M
  • 327 Small Block Chevy Engine Build Edelbrock Intake Manifolds
    Three subtly different intake manifolds were tried during dyno testing. One was an out-of-the-box Super Victor, while the others were fully ported Super Victors from different sources. The mysterious black lung on the right was part of the high-horsepower combo.
    Three subtly different intake manifolds were tried during dyno testing. One was an out-of-

It's All In Your Heads
It's always nice when you can rely on your neighbors for a helping hand-especially when you're shooting for a big hairy horsepower number and your neighbor just happens to be cylinder head maestro Air Flow Research. Add in the success that Latimer had with his first 327, and it was a given that AFR would get the call for this project. AFR's Tony Mamo suggested a set of the company's 195cc Competition Ported Eliminator heads. That's right, even though emphasis here was on high-rpm horsepower, the parties involved weren't willing to entirely kiss off the lower end and wanted a better balance. And that's where the Competition porting job comes into play. Most of us hear "competition porting" and think WOT, max-rpm power. But a motor is never just at its peak. It's always moving through the rpm range, even when it's at full throttle. In that case, ultimate high-end performance is not necessarily the main reason for choosing Comp porting. "It's always best to run a smaller head that reaches your CFM target or goals, especially in any application that spends a fair amount of time on the street," explained Mamo. "When you have the same airflow through a more conservatively sized port, the torque and the low/midrange power is a lot stronger, and the snap and crispness in part-throttle operation is vastly improved, a factor you will never see measured or quantified on a dyno, but that's very welcome once you experience it." Well, couldn't they just have put a bigger head on it? Negative, said Mamo. With the 210 street heads, you'd save $500 but end up with a lazier engine and without the linear power curve. "I always recommend Comp porting to anyone who's serious about what they're doing," Mamo elaborated. "It does it all better: It has higher airspeed for better cylinder fill, it improves low/midrange torque and power output, it has better throttle response, and it improves fuel economy-it's just more efficient."

  • 327 Small Block Chevy Engine Build Hooker Headers
    Although headers with larger-diameter tubes were tried, best results were achieved with Hooker 1 3/4-inch Super Comp long-tubes, fitted with 18-inch extensions.
    Although headers with larger-diameter tubes were tried, best results were achieved with Ho
  • 327 Small Block Chevy Engine Build Comp Solid Roller Lifters
    A peek down the valley during an intake change revealed the Comp solid-roller lifters, as well as the Manley 5/16-inch pushrods. These pieces have a 0.080-inch-thick wall for improved valvetrain stability. And while many 195cc runner heads match up to a Fel-Pro 1205 intake gasket, AFR's Mamo pointed out that the Comp ported head is closer to the larger 1206 gasket.
    A peek down the valley during an intake change revealed the Comp solid-roller lifters, as
  • 327 Small Block Chevy Engine Build Black Ported Intake Manifold
    We already mentioned that best power numbers were obtained with the black ported intake-fitted with a stack of phenolic spacers. The four-hole spacer was added first to add to the plenum volume; the potent 327 picked up about 6 hp.
    We already mentioned that best power numbers were obtained with the black ported intake-fi
  • 327 Small Block Chevy Engine Build Adding Tapered Combo Spacer
    A tapered combo spacer was then added to this intake sandwich. This type of spacer helps get the mixture flow out of the carb, filling in dead air spots and eliminating backswirl, according to Mamo. This one picked up another 2 hp. Latimer's Chevy II has a cowl hood on it, so he can actually fit these spacers underneath if he chooses to.
    A tapered combo spacer was then added to this intake sandwich. This type of spacer helps g
  • 327 Small Block Chevy Engine Build Aed Performance Carb
    Two carbs were used on this 327, and the highest horsepower number was obtained with this AED Performance 950 HO carb. AED buys unmachined castings from Holley, then does all its machining in-house, does precise parts matching, and installs its own fuel curve and calibration, among other features. The 950 HO actually uses a 750-cfm HP body combined with an 850-cfm baseplate. Real-world flow, according to AED, is 825 cfm. The larger baseplate allows airflow for power up top, while the smaller body enhances responsiveness since the venturi controls the signal to the boosters.
    Two carbs were used on this 327, and the highest horsepower number was obtained with this
  • 327 Small Block Chevy Engine Build Aed Mixer
    The AED mixer came out of the box with 78 primary jets and 86 secondaries-this 327 liked things on the lean side for its most powerful dyno pulls, so the front side was pulled back four sizes to 74, while the secondary side was cut back two sizes to 84.
    The AED mixer came out of the box with 78 primary jets and 86 secondaries-this 327 liked t
  • 327 Small Block Chevy Engine Build Milled Cylinder Heads
    To obtain a compression ratio in the 11.5:1 range, the heads were milled down 0.030 inch, reducing the chamber size from 65 cc to an even 60 cc. About the chamber: Mamo called it an "efficient heart-shaped design that helps low and midlift flow." Below about 0.400-inch lift, the chamber is more important than the port in promoting flow, since the mixture must get past the valve. After that, the valve is farther away, and the chamber is less critical.
    To obtain a compression ratio in the 11.5:1 range, the heads were milled down 0.030 inch,
  • 327 Small Block Chevy Engine Build Cnc Machined Cylinder Heads
    According to AFR, its Comp ported heads feature a finer level of CNC work, allowing for entirely accurate reproduction of the original port design. This is evident in the intake ports, which also feature a ramp or air dam of sorts in the intake bowls, which Mamo said "does some very beneficial things for the airflow curve in general." Never one to mince words, he added, "It's the most efficient port design out there in a medium-sized 23-degree cylinder head."
    According to AFR, its Comp ported heads feature a finer level of CNC work, allowing for en
  • 327 Small Block Chevy Engine Build Cnc Machined Exhaust Ports
    The exhaust ports also receive the same precise CNC treatment as the rest of the head, but lack the wings found on the intake side. They do, however, have a generous short term to allow the burnt junk an unhindered exit path.
    The exhaust ports also receive the same precise CNC treatment as the rest of the head, but

Although Latimer was confident that his 327 creation would reach the 500 mark, he was a bit surprised to pass it by so much, and admits that he would have made some different component choices if he'd known. To that end, he's got a set of lightweight Wiseco pistons and rings on order, along with 6.250-inch rods to increase the pistons' dwell time at TDC and further enhance that rod/bore and stroke combo. Our only question is, "When can we come check it out?"

CAMSHAFT SPECS
Manufacturer Comp Cams
PN 12-773-8
Grind number XR292R
Type solid roller
Valve lift 0.582/0.588-inch,intake/exhaust
Valve lift
(with 1.6:1 rocker arms)		 0.621/0.627-inch,intake/exhaust
Duration at 0.050 254/260 degrees,intake/exhaust
Lash (hot) 0.016/0.018,intake/exhaust
Lobe separation 110 degrees
BY THE NUMBERS
FLOW FIGURES
Lift Intake Exhaust
0.200 140 115
0.300 202 165
0.400 248 200
0.500 280 217
0.550 292 220
0.600 300 225
*cfm at 28 inches H2O
DYNO DETAILS
Headers Hooker 1 3/4-inch long tubes w/18-inch extensions
Advance 36 degrees
Fuel 91-octane
CARB
Type AED 950 HO Series
Jets 74/84
  primary/secondary
PULLS
Max torque @ rpm 433 @ 5,600
Max power @ rpm 553 @ 7,100
Average torque 411
Average power 447
RPM LB-FT HP
3,900 380 282
4,000 378 288
4,100 384 300
4,200 381 304
4,300 389 319
4,400 397 332
4,500 397 341
4,600 401 351
4,700 406 363
4,800 403 368
4,900 405 378
5,000 418 398
5,100 416 404
5,200 429 424
5,300 426 430
5,400 431 443
5,500 428 448
5,600 433 462
5,700 430 467
5,800 425 469
5,900 433 486
6,000 426 487
6,100 422 490
6,200 431 508
6,300 427 513
6,400 427 521
6,500 426 527
6,600 426 535
6,700 419 535
6,800 417 540
6,900 412 541
7,000 407 543
7,100 409 553
7,200 402 550
7,300 393 546
7,400 388 547
7,500 381 545

327CI Build Sheet
Specifications not listed are the same as stock. Except as noted, all dimensions are in inches or fractions thereof. All prices sourced through JGM Performance Engineering and AFR.

Displacement 333 ci
Bore x Stroke 4.040 x 3.250
Compression 11.52:1
Rod center-to-center 6.000 inches
Piston deck height +0.005
Chamber volume 60 cc
Rod bearing clearance 0.0022
Crank endplay 0.0060
Piston ring endgap 0.026 top, 0.020 second
Main bearing cap torque 70 ft-lb (moly-lube)
Rod bolt torque 65 ft-lb (moly-lube)
Head bolt torque 70 ft-lb (moly-lube)
PRICE LIST
Ackerly & Childs 9771-45 gap-to-fit moly rings $130
AFR 1095 195cc SBC Eliminator Comp cylinder heads 2,079
8041 1.580-inch solid roller valve spring upgrade 207
8508 titanium retainers 129
ARP 134-2501 balancer bolt 27
134-3703 12-point High Performance head bolts 138
434-2101 12-point stainless intake bolts 39
134-5402 main studs 52
134-7901 oil pump drive shaft 13
Autolite AR3910 spark plugs 40
BEP 70082 front cover 35
Canton 15-246 SBC F-body RR Power Pan 485
20-013 SBC pickup 3/4-inch tube 40
Comp Cams 12-773-8 solid roller cam 367
818-16 solid roller lifters 430
1105-16 Hi-Tech stainless rocker arms 480
Eagle S/R 6000SBLW 6-inch I-beam rod 299
Engine Tech CC400 cam bearings 17
EP155 oil pump, 3/4-inch pickup 33
Federal Mogul/Fel Pro 1010 0.039-inch head gaskets (2) 146
1206S-3 intake gaskets 33
TCS45121 front cover gaskets 13
1880 one-piece oil pan gasket 43
138M 10 race main bearings 98
8 7065CH 10 race rod bearings 90
2912 rear main seal 31
GM N/A stock replacement 327 balancer 100
14011012 water pump 130
JGM Performance Engineering
(labor on 1964 327ci two-bolt main block)		 thermal clean and magnaflux block 108
bore and hone block with dual-torque plates 308
align and hone main journals with ARP studs 188
regrind & micropolish factory steel small-journal crank 134
balance rotating assembly 250
custom blueprint and assemble long-block 850
dyno test and tune 750
KB Performance KB155 +40 pistons 454
Manley 25716-16 5/16-inch, 0.080-inch wall pushrods (+0.200) 180
Moroso 60461 cam button 18
93020 valve cover gaskets 62
MSD Ignition 83645 digitial HEI Module 182
8225 HEI Coil 117
Pro Gear PG4100-1TB timing set, 1/2-inch pitch with Torrington bearing 150
Total $9,475
ADDITIONAL ITEMS
AED Performance 950 HO Performance Carburetor $700
Slover Porting Service fully ported Super Victor intake (porting only) $450
Sources
Air Flow Research
Valencia, CA
877.892.8844
airflowresearch.com		JGM Performance Engineering
Valencia, CA
661.257.0101
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