This is one of those GM Crate Engines from 1991 with the Mexico heads - 76cc, 1.94/1.50 8.5:1 compression, Chevy 350

Upgraded to Edelbrock EStreet Aluminum Heads 70cc, 2.02/1.60 185cc intake runner
RPM Performer Manifold
AVS Thunder 650 carb
Roller Rockers
Lunati Cam 10120702 .468/.489 at .0500 219 duration
New HEI Dizzy with plugs and wires


Runs great with headers and 2.5 inch dual exhaust, but when you get on it from idle and even when cruising - it pops/spits/coughs/misses just a second and then recovers. Played around with every setting on the timing.

Will check for vacuum leaks next, but also found out that it may need an extra shot of fuel and that there are 3 adjustments/positions for the accelerator rod. Does the same thing with a Performer 750 carb - any suggestions?