KC John

I have a 1970 block that looks to have low mileage or has been rebuilt recently going by the condition of the cyl walls and how clean the insides are.

I also have a ZZ3 engine with some type of damage but I have not found it yet. It had so much blow-by that my breather on my valve cover was oil soaked and when I pulled the breather off it felt like an exhaust pipe instead of a breather. I think it has a broken or worn out oil ring in one or more cyls. It has much better internals than the other block with 1 piece rear main seal and forged crank.

My eventual plan is to put a ProCharger on one of the engines running around 5lbs of boost. I need to do this right, but I also need to keep the cost down as much as possible and still reach my goals. I'd like to sell what ever parts I don't use to help fund my project.

I was considering pulling the pistons replacing them with forged ones, new rings and put it all back together. Just not sure if the compression ratio would be too high to use with a blower.

What would you do if faced with this situation?

cardo0

I dont know what kinda parts are in your '70 motor but I do know the ZZ3 has tight head chambers. For a positive pressure engine (supercharged/turbo charged) you want to optimize volume above the deck of the block meaning you want to use large chamber heads with flat top pistons for a modest compression ratio less than 9.5 w/aluminum heads. I think lower than 8:1 compression is to low for even a supercharged engine. You should read up on supercharger engines. Plenty of books on this and you may even find one at the local library to check out for free.

So the ZZ3 has good forged rods and crank but I would want some 76cc chamber heads on top. Swap in forged pistons to.

'70 block may have forged parts to but you didnt list anything about it. BTW the older 2 piece rear main seal cranks are stronger do to the fact the flywheel bolt pattern is a larger diameter.

Good luck.

KC John

That's what I figured. I think with new forged pistons (which I might need anyway) and the right heads I'll be $$$ ahead with the ZZ motor rather than messing with the 1970 block. Maybe I'll just put the aluminum L98 heads on that motor and sell it that way.

cardo0

John you want to post the casting and stamped numbers on the '70 block & heads. If it were me I would pull the oil pan to and verify crank is cast or forged - it suggests you have that engine out of the car now. I say this because many of the corvette motors - but not all - had forged crankshaft, rods and pistons too. I'm thinking L82 but in 1970 there was a different designation.

What I'm saying is you may have the short block you want but you have to look first and verify all the parts. Believe it or not even some of the stock heads would be acceptable to use with a blower - even more so at a low 5PSI.