Perserving Your Classic Corvette Engine

How to preserve the most important component in your Corvette.

Jeff Bernhardt Oct 7, 2008 0 Comment(s)
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You've done the research, and you know that if you remain at status quo, continued use with today's petroleum products, unaltered, will deteriorate the internal components of your engine. The first option before you is to set your engine aside and replace it with something else. Lay out a master plan for your project before you get this far. Once your engine is hanging from a hook, you've committed to doing something-right or wrong. Remember this original numbers-matching engine is not worth as much to anyone else as it is to the owner of the car that has the VIN tag that matches it. So, hopefully, preservation of this engine is in your plans, and you keep it rather than sell it. Don't get caught up in the temptation that a few bucks for your original engine will offset some of the cost of a new one. Disassemble enough of your engine so that you can put major components in plastic bags, twist-tied. This is the "bag and tag" approach. Store all components up off the floor so they will never sit in water. Remember, "preservation."

Many times a restoration project will come into my shop that doesn't have its original engine, so we're forced to install a replacement of some sort. The GM crate engines make a great choice because they are readily available at a decent price point for all that you are getting. The versatility is impressive because they can be dressed to the nines for show, or disguised with a vintage look with the proper parts installed onto them. the internals are new, strong, and will withstand some moderate street abuse. And they will out-perform many of the stock engines installed in our beloved classics. I've heard from the group that are tired of driving dated technology-so dated that a four-door Honda can beat them from traffic light to traffic light. It's sad but true, there was a time when the base V-8 engine in the Corvette offered a dismal 165 hp, whereas the 3.5-liter V-6 Honda rental car of today boasts 268 hp. The pair-up on the boulevard would be a bloodbath. I've also heard from the group that simply wants a more efficient and powerful engine for no other reason than because the technology is there. Well, the technology is there, and we can make it look period-correct. I'll share that with you too.

The other side of the coin takes your original engine and not only replaces the worn-out parts (some of which may not be evident), but also updates it with some of today's current technology. If you stand still in a changing environment, you're dead. This will certainly be evident if you rebuild your engine the same way as you have in the past because if you do, you will more than likely experience a failure. You can no longer afford to make the assumption that your pressed-in rocker studs are ok, or that the connecting rods are pretty strong, and, therefore, fine. You have too much at risk to gamble this way. And how about another new twist: With the advent of roller cam technology, oil companies have been able to reduce the zinc dialkyl dithiophosphate (ZDDP) in today's motor oil. This reduction protects the catalytic converters on all our everyday grocery-getters where some oil is seeping past the rings, but the trade-off is that it eliminates some of the lubricity of motor oil under extreme pressure situations. What does this mean to you? This extra high-pressure lubrication is exactly what is needed for a camshaft to survive with a flat-tappet lifter grating against its lobes. What has happened is this: stories have circulated from all over about how someone else's brand-new camshaft is wiped out before it ever sees 20 minutes of operation during the break-in period. The engine drops a couple of cylinders, the cam lobes are flat, and the oil is black from the metal floating around in it. How do new cars get by with this oil? Because flat-tappet technology is a thing of the past. Your new camshaft for your engine rebuild will come with multiple warnings to this effect, and a statement of voided warranty if strict procedures are not followed. These procedures call for special light-pressure springs to be installed on the valves for the break-in process, along with additives to be put in the oil. What is your outlook for long-term survival? Well, you can put additives in your oil, try to find some CI-4 spec diesel motor oil (not CJ-4), or look at a couple of other options we'll talk about in this segment.

We Corvette owners are a die-hard bunch. We meet the problem head-on without flinching, we don't take no for an answer, and some of us anal NCRS-type guys even consider it a challenge when someone says "that can't be done."


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