well, the truck has always backfired, but i didnt notice that it was a backfire until recently. any ways to fix it? how bad is it? it isnt very loud, just sounds like i have a rock bouncin around in the pumpkin [:'(]

 

When is it backfiring? Maybe either your timing is advanced too far, or too little exhaust system backpressure..

 

Or its really rich and putting raw fuel in the exhaust.Tha was a very common problem on carbs

 

It could be A/F ratio also, just a suggestion.