Gold Lifetime Member
Join Date: Dec 1999
Location: Yorkville, Illinois USA
hmmm, detonation city, hope it's not trashed. I did a similar 400 long ago, 64cc heads, flat tops, but the cam was 108 centerlines, and cranking compression around 185. It was a bear to make that thing stop pinging. You need to come half way back on both the cam and the heads. 70cc edelbrocks would be good on a 400, and a cam with enough overlap to kill some of the pressure at low rpm's. And tune it real careful like, start rich and retarded, and go easy till you get it right. I just love 400's!!!