Back in the Before Times, Jeff Latimer of JGM Engineering in Southern California wanted to do some road racing and built a 357 cubic inch small block Chevy for a Gen III Camaro to run in the Silver State Classic Challenge. Life then intervened as it often does. The engine was pulled, the car was sold, and that was the end of it—or so Jeff thought.
Two years later, Jeff made another attempt at going road racing. He took the 357 out of mothballs and decided to go through it. Once again, life threw in a monkey wrench by way of the COVID-19 pandemic.
With parts becoming difficult to get, the rebuild slowed to a crawl. But Jeff kept at it and recently finished the 357. The 11:1 compression small block made 561 horsepower at 7,000 RPM and 464 lbs.-ft. of torque at 7,100 RPM on the JGM dyno—a just reward for the time and effort expended to build it.
We thought you would want to see what it takes to build a high-winding small block like Jeff’s, so have a seat and we’ll guide you through the process.
Block and Reciprocating Assembly
Jeff based the 357 on a 350 four-bolt main block set up for local stock car competition. The block was bored to 4.040 inches and modified to accept piston oil cooling jets, screw-in freeze plugs, and a dry sump oiling system. The crankcase is filled with Ross forged pistons and six-inch Manley H-beam rods bolted to an Eagle Specialty steel crank.
Camshaft and Cylinder Heads
Jeff ordered a COMP Cams Xtreme Energy solid roller camshaft from Summit Racing. It speced out at 254°/260° duration @ .050 and .582/.588-inch lift on a 110-degree lobe center. He used a set of early-production AFR 195 heads with solid roller springs and titanium retainers he had on the shelf.
Jeff dropped the 357 on the engine dyno and was rewarded with 540 horsepower and 460 lbs.-ft. of torque. Not bad for a first pull, but Jeff believed the small block would do even better with some modifications. He had friend Chris Brintell do some extensive port work on the AFR heads. Jeff also modified them to accept 3/8-inch diameter pushrods and shaft-mounted roller rocker arms. He replaced the valve springs with COMP Cams dual valve springs and matching titanium retainers.
Jeff also swapped the COMP Xtreme roller cam for a more aggressive COMP Oval Track solid roller with 10 degrees more intake and eight degrees more exhaust duration, .645/.630-inch lift, and a very tight 106° lobe center to build maximum horsepower from 3,500 RPM on up.
Jeff replaced the Edelbrock Victor Jr intake manifold with a Super Victor intake designed to make power in the new cam’s operating range. Chris Brintnell port matched the intake to the AFR heads.
Jeff use crossover-style headers with primary tubes that step up from 1 3/4 to 1 7/8 inches and merge into 3 1/2-inch collectors. A wideband O2 sensor in one of the collectors allowed Jeff to monitor the air/fuel ratio.
Running 100-octane unleaded gas and 35 degrees of ignition timing, the 357 made 561 horsepower and 464 lbs.-ft. of torque—a gain of 21 horsepower and four lbs.-ft. of torque. More importantly, the power peak moved up from 6,700 RPM to 7,000 RPM.
Jeff now has a small block screamer ready to race. The challenge will be finding a car to drop it into.
Jeff started his build with a 350 four-bolt main block set up for local stock car competition. The block was bored .040-inch over and modified to accept piston oil cooling jets, screw-in freeze plugs, and a dry sump oiling system. (Image/Jim Smart)These breather tubes will improve crankcase breathing without allowing oil drainback that can cause excessive crankcase windage. (Image/Jim Smart)The 357 is fitted with an Eagle steel crank, six-inch Manley H-beam rods, and Ross Racing forged pistons. These parts are more than capable of handling the power and endurance demands of road racing. (Image/Jim Smart)Block plugs can blow out at high RPM. You can secure the plugs with JB Weld or secure them with screws as Jeff did here. (Image/Jim Smart)The boss behind the cam sprocket had to be ground down to clear the double-roller timing set’s cam sprocket. This must be done with any Chevy small block so the sprocket seats properly. Jeff installed drainback screens to catch any debris that could cause engine damage. (Image/Jim Smart)An adjustable crank sprocket is important for any high-performance engine build. It allows you to advance or retard valve timing for your particular build or set it according to the cam card. (Image/Jim Smart)We cannot stress enough the importance of establishing true Top Dead Center (TDC) before degreeing in the cam. Jeff checks piston positioning first using a dial indicator, then gets to the business of degreeing in the cam. It was installed straight up. (Image/Jim Smart)Jeff gave us the lowdown on head gaskets. The Fel-Pro MLS gaskets call for perfectly machined surfaces like we find with GM LS/LT and Ford Coyote engines. Composition head gaskets like the Fel-Pro Print-O-Seal should be used with iron heads on an iron block or aluminum heads on an iron block. The MLS gaskets are .041-inch thick. (Image/Jim Smart)AFR introduced the Eliminator aluminum cylinder heads for small block Chevy in the 1990s. Jeff had a set of those early Eliminator heads with 195cc intake runners sitting on the shelf. The latest Eliminator heads are better still. They’re available with fully CNC-ported 65cc or 75cc combustion chambers and 195cc CNC-ported runners for exceptional airflow out of the box. (Image/Jim Smart)Jeff had Chris Brintnell port the heads to improve airflow. (Image/Jim Smart)Because this engine is for road racing competition, Jeff opted for shaft-mounted T&D roller rockers. Summit Racing offers shaft-mount rockers for small block Chevy from Brodix, COMP Cams, Jesel, PRW, and Scorpion. (Image/Jim Smart)Jeff stresses the correct use of gasket sealers. He uses Gasgacinch sparingly around intake ports. Cooling passages get a thin application of Permatex’s The Right Stuff. (Image/Jim Smart)Because this 357 will live at high RPM, Jeff went with an Edelbrock Super Victor single-plane intake manifold. The manifold improves power in the 3,500 to 8,000 RPM range and has runners with an extended, constant cross-sectional area to improve midrange torque. Chris Brintnell port-matched the Super Victor to the AFR cylinder heads. (Image/Jim Smart)Holley’s Classic HP Series carburetors feature a contoured venturi inlet for balanced air flow, screw-in air bleeds for precision tuning, high-flow metering blocks, and Dominator style fuel bowls. Other features include progressive mechanical secondaries, 30cc dual accelerator pumps, and four-corner idle control. Jeff experimented with 830 and 930 CFM carburetors on the dyno; the 830 gave the best numbers. (Image/Jim Smart)Jeff went with an MSD Pro-Billet distributor for the spark. He locked out the distributor and converted to a larger cap to prevent arcing and crossfire. Jeff also used Scott Performance ignition wires based on his experience in circle track racing where the wires are popular. Timing was set at 36 degrees BTDC for the dyno sessions. (Image/Jim Smart)Jeff uses ATI Super Dampers for the majority of his builds. The dampers have inertia weights with computer-machined grooves for elastomer strips. The strips can be replaced or swapped with different durometer strips to fine-tune the damper for specific engine combinations. (Image/Jim Smart)This belt-driven three-stage oil pump has one pressure stage and two scavenge stages. Dry sump oil systems help prevent oil starvation during high-G cornering and braking. They use a separate reservoir to hold the oil. That means less oil whipping around the crankshaft and causing horsepower loss due to windage. (Image/Jim Smart)A KRC serpentine belt drive system runs the power steering, water pump, and the Powermaster alternator. A separate belt runs the dry sump oil pump off of the crankshaft. (Image/Jim Smart)On the JGM dyno, the 11:1 compression small block made 561 horsepower at 7,000 RPM and 464 lbs.-ft. of torque at 7,100 RPM—a just reward for the time and effort expended to build it. (Image/Jim Smart)
Jim Smart is a veteran automotive journalist, technical editor, and historian with hundreds of how-to and feature articles to his credit. Jim's also an enthusiast, and has owned and restored many classic vehicles, including an impressive mix of vintage Ford Mustangs.
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