My carb is backfiring when it is revved from idle at 1300 RPM's. The primary squiter is 37 and secondary is 25. I am thinking that it is running to rich? The jetting is all stock, the carb came off a 502BB. I checked the floats but i dont think that the floats being close to being adjusted would cause it to back fire. Specs on the car are in sig. the cam is a comp XE284H-10 (swap 4 and 7 plug wires) I broke the cam in then tried to adjust the idle mixture screws but im not sure which way leans it? I think it is out right? Thanks for the help chas

Ok so i swtiched the squiters and it seems to run a lot better. Also i switched the plug wires to what it should be and it cleaned up all of the backfiring. My floats are also all adjusted now i just have to figure out the idle mixture screws so if someone runs a Comp Cams XE284H-10 part number 12-661-47 DO NOT swap the firing order. I had nothing but problems until i put it back to stock configuration.

I think clockwise leans it, counter clockwise richens it. With motor at operating temp and idling, turn 1 screw at a time clockwise until you hear a change in the smoothness of the running, thenback it out till it runs its best and stop there. Then do the same for the other screw and thats it. I use a base setting of 2 turns from bottoming out and then start from there.