1966 Chateau Slate L78 Chevelle

[OneStopRestoration]

Originally Posted by Tuna Joe

One stop,
Curious what made you go with Erson cams? I know you had used Comp cams in the past.
I’m in the middle of a L89 rebuild and am trying to decide who to go with for my roller cam.

Also curious on the internal components of your engine. I know the external parts are original for stock factory appearance but are you using aftermarket rods, crank, etc?

I have a beautiful set of original GM dimple rods that I had planned on using but my engine guy has discouraged me from using them and recommended aftermarket rods.

Thanks

Thats a good question. I did call around to several smaller cam manufactures. Each one had there own recommended roller cam. The only one that talked about having a cam that was ground very close to an l78/l89/ls6 was Erson. Erson also indicated that they sell around a half dozen of these special cams per month to various muscle car owners. They also expressed that others asking have wanted the same sound characteristics of the stock solid lifter cars. The other cam companies were great to talk too but i couldn’t wrap my head around a cam with close to .600 lift in a restored muscle car and I wanted to retain the sound and specs of the original. Most of the other companies didnt even have cams below the .580s which i assumed would not work with stock valve covers. I like originality and the further away you get from that the more you will have to tinker with things like timing and carb jetting.

In terms of internals I stuck with somewhat unique 66 Hi Perf rods GM rods. I believe there on par with dimple rods but basically an earlier version. There actually hard to identify unless you have another lower hp rod to compare. With all the builds I have done the stock GM parts are plenty good. Consider for a second the abuse these motors saw back in the day. The 6223 cranks are also solid pieces to reuse. I dont like using the ones that start to get beyond .030 over on the mains or rod bearings. My dad and I are split on rocker arms, dad buys some aftermarket stockers, and go with the comp roller tips. As you may know once you go with a roller cam your changing your pushrods. Just about any brand of larger diameter rods will work, even something like Comp. Erson sells them as well. Pistons are abit of a toss up. I have noted that each engine guy tends to like a certain brand. In the case of the last 3 l78s my dad and I worked on we went with some rather pricey custom made Racetech pistons. We liked the idea because we ended up with way lighter than stock piston with a more modern less drag ring package. We also did custom so we could really dial in the dome CC to get back to as exact 11:1 compression as we could. I hope anyone reading this is laughing because if its not obvious these l78 cars to us are too valuable to take out and drive much. This brings up a point we struggle with on our builds. After the block is decked, or maybe even the heads, and you start to CC the combustion chambers you sometimes learn your either over or under on compression ratio when you do the math. That’s one of the reasons we gravitate to custom made pistons. Some might say change the head gaskets but we strive for keeping the quench area in a sweet spot range(I believe .040-.045).

Im not sure what to say about your engine guy. If i was in your shoes i would ask a few questions to understand why he feels that way. He may very well have a good reason. These cars are expensive to restore and throwing more unnecessary parts isnt something I strive for. You mentioned L89. Im gonna assume your not planning to drive this car much. If its really just a show car there is no reason to start buying new parts(pistons being the exception). I have cars I drive and cars I don’t. There is a valid reason to start changing out parts for a car you drive. One of the benefits that I have seen is newer parts are strong and lighter. Getting weight out of the rotating assembly will always provide benefits.

One last comment, ask others and learn as much as you can. Im just one data point.