So Im tuning my 383 starting from a mail order tune from MadZ28. The motor is a high compression 383, about 11.7:1 compression. Im running it in Texas (90*+) and I cant seem to get rid of knock retard. Im not sure if its real knock or not.

The timing seems very agressive and it pulls out 8* (max) at all times under heavy load.

The chambers are ported and it has good quench (.035) and the cam is big, but acts smaller due to the XE ramps. Im thinking that it needs less spark than most...

Ive tried tuning it by pulling out timing where it pulls KR, but its not seeming to work. KR is a myth to me, it always pulls KR to some extent, sometimes more than others... the only time it doesnt is in 18 BLM on coasting.

Any thoughts?

 

Desensatize the k/m.

 

Yea, already did that. I dont wanna do it anymore.. it might be real knock.

 

Did you try using some race gas. The heat and compresstion maybe causing it. What temp is the car running at ?