if you're not running an lt4 km you're probably getting a **** ton of timing pulled which would greatly hurt your performance. the other thing i can think of is that you need more fuel pressure like has been suggested earlier. only other thing i can think of is you ordered your afr heads with big chambers and killed all your compression with it they like to sell 72 and 64cc chambers and stock lt1 is 58 so if you got big chambers you flushed a lot of your CR away.

EDIT: i'd probably toss the 1.5 rockers and throw some 1.6 rockers on there the added lift will only benifit you with those afr's. another thing just for peice of mind you might wanna put a fuel pressure gauge on and tape it to your windshield so you can see what it does when you make a pass at the track, could have a week fuel pump and not realize it.

 

Sounds like that's what happened. Changing to 64cc heads lowers compression from 10.4:1 to 9.3:1 and 72cc heads lower compression all the way down to 8.6:1.

Jeff D.

 

Iwent from a best of 13.6 at 104 to 13.1 at 109 with hot cam 1.6 RR and pcmforless tune.

You've got issues, for sure.