August 2011 Chevy High Performance Q&A

Performance From Around The World

Kevin McClelland Jun 30, 2011 0 Comment(s)
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A: Boy, does this bring back some memories. Around 1983 we were running our ’57 Chevy in Super Gas. We had gone through all the four-bolt 427 blocks we had. Everything was junk and had been run for too many years. We’d heard of folks running two-bolt blocks with good success. They would run main studs and everything was just fine; they weren’t trying to move a 3,000-pound ’57 Chevy at 9.90 seconds at 135 mph. Nothing like trying to push a brick through the wind. Well, only having 440 cid (0.060-over 427) we’d buzz the engine to 8,500 rpm in the lights. Even with taller gears (4.88s versus 5.14s) the little engine just couldn’t pull the weight with the higher gearing. Everything was going just fine until we “drove over the crankshaft” at Orange County Raceway at the 1983 Super Chevy Sunday race in the semifinals! The front main cap pulled right out of the block, breaking the crankshaft right in front of the third main. As you can well imagine, this broke just about everything we owned. Luckily, we were able to get the car stopped safely and race it another day.

Your build would not be as radical as our early 427, but with the quality of components these days, it’s very easy to make power. The main reason we killed the big-block was from the high rpm required to run the e.t.’s. If you can keep the rpm in the 6,500-7,000 range, it will live. But again, building horsepower is way too easy these days. Also, you’ll have 1/4-inch more stroke than we were tossing.

To give you peace of mind, either find a core four-bolt block or have four-bolt caps installed on your current two-bolt case. Milodon offers four-bolt retrofit caps machined from high-strength ductile steel material, which has the proper balance of strength, yet is not too rigid like a billet main cap. The caps come in both straight and angle side bolt configurations. The angle side bolts are much stronger than the standard vertical main bolts. These caps will require a standard line bore and are designed for 0.030 inch of material removed from the main cap mating surface on the block to clean up any existing damage. This is an easy swap, and you should line hone the block anyway to prep for a performance build. The main caps are sold under PN 11200 for the center three mains, and PN 11210 for the front main. While you’re at it, pick up the main studs, PN 81133 for non-windage tray applications, and PN 81134 if you have a tray. This upgrade will strengthen your standard block to allow you to make the power you’re looking for today or in the future.

If you are going to do much street driving, limit your compression ratio to the 9.5:1 range. We’re currently running 10:1 with my 524 in the Super Gas roadster. We pull out of the lanes at 150 degrees, and pulling off the end of the track the temps have climbed to 180 range—all of this with 32 degrees of total spark with no detonation. We’d be concerned with the higher ratios for street driving if you can’t keep the temps under control.

Your selection of components is spot on for your application. The AFR heads will work great as an all-around torque monster. These heads, in conjunction with the long-runner Edelbrock Tunnel Ram manifold will move your Cavalier quite nicely. Enjoy the torque and don’t spin the thing over 7,000 rpm. It’s a waste of time—e.t., that is!

Burnout School

Q: Last year, my ’55 Chevy Bel Air came out of a two-year build, an awesome, beautiful car and fun to drive. It has a stock LS1, 4L60E, an aftermarket frame with C4 Corvette suspension front and rear, and a new GM Performance computer. The car runs great, but it will not spin the tires. Other cars with this engine will burn the tires up. What could be the problem? Any suggestions would be appreciated.

Gerry Kennon

Via email


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