Hey, I just did a motor swap on my 84 camaro, and I am still trying to tune all the kinks out. I thought it was running pretty rich, so I was tuning my carb when it backfired...almost took my face off. Lucky for me, I thought it could happen so I had my face down. I have no air/fuel ratio gauge and besides the dollar bill trick, I don't know any other way to properly tell what the problem could be? This happened about 2 weeks ago, and the problem has been off and on. suggestions?

 

Sounds like it could be timing related. Check it and make sure it's set right with the vac. advance disconnected, then try to tune the carb. You can use a vacuum gauge to set the idle mixture, and read the plugs to set WOT. I usually keep a fire extinguisher handy BTDT. BTW, idle speed will also affect timing.

 

yah a fire extinguisher usually comes in handy when dealing with that. I will remember that for the next time (hopefully not =) )

 

i almost caught a fireball with my face once too, havent put my head near the carb since. my timing was too retarded, i think like 4°btdc, i set it to 16btdc

 

whats the dollar bill trick???

 

Bad timing will definitely cause that kind of problem. Also, are you sure that your power valve isn't bad? Backfires on Holley carbs usually take out the power valve, thus causing it to run even more rich, especially at idle.

Depends on which model/year of carb you have.

HTH,

 

Naw, my power vavle is good I am pretty sure. It's a brand new holly, but the engine I am still tuning. That's why I try to narrow the problems down to the most obvious first.