Perserving Your Classic Corvette Engine

How to preserve the most important component in your Corvette.

Jeff Bernhardt Oct 7, 2008 0 Comment(s)
Corp_0808_27_z Zz383_crate_motor Poly_lock 2/32

Again, a means to an end. Turns out the culprit is the poly-lock nut that stands up too high for the valve cover to fit. The Restoration Station cured this little problem by having their own nuts made out of annealed 4150 steel, blackened and hardened to 44 Rockwell. Unbeknownst to us, Comp Cams had already addressed this problem with their own line of short nuts listed as High Tech under part number 4600-16. These may be the best kept secret in their catalog. These nuts are designed to fit either the Comp Cams 8650 chrome-moly Pro Magnum roller rocker or the Hi Tech stainless steel roller rocker in small-block or big-block Chevrolet applications. If you have an engine with the aluminum covers and drippers formed into the roof of them, roller rockers will not fit without modifying the drippers.

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Here's the difference in rocker height with the original poly-lock in the background, and our new nut in the foreground. It's also the difference in running aftermarket or original valve covers. You can also run roller tip rocker arms with stock valve covers since they use the standard self-locking stock variety hex nut. That's better than the stock stamped-steel rocker, but it's kind of like driving all the way to the pool on a hot summer day, but never getting wet.

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If you insist on rebuilding your engine with an original-type, flat-tappet cam, do it wisely. If you simply build the engine, pour in the oil, and fire it up, you will likely wipe out your new camshaft in a matter of minutes due to the lack of zinc in today's oil. Here's a Comp solid lifter cam with a warning tag attached to it with strict instructions about camshaft break-in procedures. Also shown are two must-haves: Comp's assembly lube in a pouch (PN 103) that comes with every new cam, and oil additive in a bottle (available separately, PN 159) to compensate for the lack of zinc in today's motor oil. The camshaft shown here has been nitrided-an extra hardening procedure available from Comp Cams for about a hundred bucks. There is no way I would install a flat-tappet cam today without stepping up for this additional procedure. Ask them about it at

Corp_0808_30_z Zz383_crate_motor Big_block 5/32

The proof is in the pudding. Here's a full-roller, 390hp, '67 big-block, and, except for a couple of Corbin heater hose clamps and one or two other details, it's ready for NCRS judging. It is totally stock on the outside, but it has longevity and performance-enhancing details on the inside that will help preserve this valuable engine.

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Another small-block version, this time a '69 350/350hp beauty that is, once again, a full-roller on the inside. This information and these ideas are presented to you to be thought-provoking, but also to help keep your classic Corvette on the road-something that will benefit all of us in the hobby.


Comp Cams
Memphis, TN 38118
Classic Motorsports Group
Chevrolet Performance Parts
Detroit, MI 48232
Hedman Hedders
Whittier, CA 90602
Lectric Limited
Bedford Park, IL
Paragon Corvette Reproductions
Swartz Creek, MI
Fuel Injection Specialties
San Antonio, TX
The Restoration Station
Springboro, OH


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