I was basically lugging(4 speed) the car at an idle like 1-2MPH and stabbed it. Then I get a big old flame under my cowl :eek: This has happened twice since I swapped over from a 700DP to HP950 and spacer. The cam does have a lot of overlap.

Would that be too much pump shot? It seems to be running good maybe still a little rich.

sorry, can't answer your question, but my car does the same thing! if you do find out please let me know, its really starting to bother me.
-Jay

most likely not enuph pump shot, or a vacum leak. In my experience, a pop through the carb is usually caused by a lean condition or retarded timing.

try larger accel pump nozzles or a diff pump cam
sounds like a lean backfire to me

edited by me.
asked dumb question

Thanks guys I'll play around with it.

It's too lean. When you go from a smaller carburetor to a larger carburetor on the same combination the air velocity through the carburetor will slow down. This means you will need to increase the volume of fuel being feed. Going from a 750 to a 950 (essentially a 750 with an 850 baseplate) you'll need to go to a larger squirter nozzle size.

Definatly a pumpshot problem. Get more fuel in there, faster.