Little puzzled here anyone know why the zz5 and zz6 motors are 9.72 ratio and the zz385, zz430, sp350 are 9.6? From what i can tell they have the same pistons, heads and head gaskets. A sp350 with cam and rocker upgrades on paper should make over 430HP and be the cheapest new GM long block compared to the zz6, would a thinner head gasket also be beneficial?

https://www.chevrolet.com/performanc...sp350-385-base
https://www.chevrolet.com/performanc...gines/zz6-base

 

Probably an error in their information unless they dont use same gaskets or if the piston to deck height is different but i doubt that

zz6 does have a single plane intake and better rocker arms but not sure if thats all worth the extra cost

cam and single plane on the sp350 would haul the mail. Or even a performer rpm ported abit.

 

the only diff in part number i can find is the heads but there both listed as 62cc so who knows have to make some call to se what the people who sell these say about it

would be selling valve covers intake manifold water pump dizzy reusing camaro efi with a stealth of super ram, corvette aluminum water pump and magnesium valve covers