Good morning all. I've been working on a 292 with a 3x2 intake for several years now. I've gotten to a point where I can drive the vehicle for short trips, but I'm intermittently getting a backfire under acceleration once the engine warms up. Its also cut off on me twice at a stop. I think it might have been vapor lock, because it restarted pretty quickly. Ive sent the carbs out to be professionally rebuilt. I called the cam manufacturer and my initial timing is where it should be. (10⁰ btdc) I've been trying to do some research about what else might be causing my concern. I'm wondering if I'm getting an issue from the heat riser ports running under my center carb. I'm using the wide open gaskets, not the truck ones with the smaller opening. Could this be my issue? I'm trying to make the power tour this year and I'm running out of time. Any help would be appreciated. Cam is an isky 301333, Weiand intake. 292 bored .090 over. Red's headers that have been ceramic coated to lower under hood temps, gasket-match porting on a set of G heads.

This is an afterthought, but would this Weiand manifold happen to be made for the '54 239 and 256 engines?  If so, intake gasket sealing would be very iffy with G heads.  Likely cause vacuum leak.

John - "The Hoosier Hurricane"

I will get the part number off of the intake when I get back to the house. The carbs are holley 94s. 1 1/16" venturi on the center and 1" on the secondary carbs

Intake is the Weiand FM 436

Jets were 56P and 50S