Mark:
Did you put this engine together? Has the engine been blueprinted? Which brand of pistons? Those 990s have a LOT of chamber, and if they're like the rest of GM factory heads they're gonna be about 5cc on the high side before cutting. A lot of times an engine doesn't have the compression you think it does. And, you could help *cheat* that compression down with your cam choice.
Looks like Eric can help ya get squared away!
