I recently built my 302 and put je 9:1 pistons,rods,edelbrok upper & lower intake,comp cam and got some head work done. It has a 75mm throtle body with 19 lb injectors. When we got it back together it back fires through the intake especially when it is cold and then gets better as it heats up. I've checked for vaccum leaks but cant find any. Someone told me it might be my maf which is a 76mm so I got a stocker and tried it but it still does the same thing. Any ideas what that might be? any info would be appreciated

 

intake leak??

 

I know you said that you had some head work done. sounds like my jeep with burnt intake valves.

 

timing might be off?

 

Like Lunchbox says, it sounds like timing. Have you checked all of your sparkplug wires to make sure they aren't crossed? Are you absolutely sure you got the cam timed properly when you installed it?

 

why in thw world od you have a 75mm tb? get rid of it. i dont care if you paid good money. you wasted money. that 302 will never need that much TB

 

Don't know if it's even possible on these engines, but sounds like the distributor might be 180 degrees off.