Hey just a quick question. After doing my 305 to 350 swap the engine is running and idle pretty good but it has a miss/backfire through the tbi when I hit the gas hard in any gear and when in neutral as well. If its cold and rev it it does not do it but after a minute or two it will start to do the same thing. It seems to get worse the hotter the engine gets. Any help would be appreciated. THANKS

 

Sounds like it's running rich. Have the timing checked. Have you given it a good tune up?(plugs,wires, cap).

Have you checked the resistance on each injector to make sure they are working properly?

 

Plugs/wires/cap & rotor are all new. New MSD wires and ignition coil. New engine just broken in on a carb, then swapped over to tbi from a different truck. I have not checked the injectors but they ran good on My freinds truck, that I stole them off of. I do have an afpr but havent been able to get a guage hooked up Yet. I thought that a backfire through the carb was generally caused by a lean condition. It will do it when worm at almost any rpm if I hammer on it!! Any more suggestions that I can do this weekend Until I get back to work would be Great!!! Thanks alot

 

It sounds like its running lean or is lean during hard accel. This can only really be fixed by tuning.