backfiring... Need guidance, please help.

Hello yall, been laying low lately but still visit the site daily.. Really dont feel like searching too much plus i wanted to say hi! Anyways, today i floored my truck and when shifting from first to second it backfired once really loud and black smoke came out the exhaust.. Wtf could that be? And i know someone will respond with" dont floor ur truck!" Thanx for any advice and take care Bsceners. Going back underground now, see ya..

I can floor mine no problem now days, the only time mine has backfired was when the timing was off, could be a simple place to start.

Post whether you did any work on this truck within the last few weeks, and exactly what was done.

the only thing other than routine maintenance was changed my belts.. The engine was rebuilt like 2 years ago and removed all emissions on stock carb.. Its runs perfectly, recently took it on an 800 mile journey through florida.. Its just this one incident.. Oh yeah, if i rev it,turn it off then back on it backfires one huge bang.. Only tried it cause i had a peanut (corolla '81) that would do the same..

in most cases id say timing but now that u say u had a corolla that did this, and my dads motorcycle does it, maybe its running overly rich. stock and weber carbs have mixture screws, play with them a little im sure youl figure it out what ever it is. backfiring is usually because of fuel that doesn't burn building up in the combustion chamber until it all detonates at once causeing a big boom. timing can cause this to due to fuel entering combustion chamber for extended amount of time b4 detination. weak coils (rarely cause backfire that I know) worn out dizzy, cap, rotor, contact points (if your truck doesn't have electric dizzy) basically either your not getting the full spark when u should if at all at 1 or more plugs, or your basically putting out the fire with fuel (rich fuel/air mix) run it for a few mins, floor it, make it back fire and shut it off and look at the plugs. if ones wet, can be overly rich but mostly its not firing everytime if at all (sometimes because its too rich, sometimes unrelated), otherwise use the color of the plugs (corrosion) to determine how your motor is running. if its really black, its really rich, if its covered in brown shit, that's oil deposits, fuel addatives ect. and im out of ideas after this one.

thanx mazdafvr.. i think its running rich, stock carb has mixture screws? if so where.. im gonna check timing later today.. dont know sh!t bout webers but i think im gonna have to get one eventually.. which one should i get? i ask because ive read there are different kinds.. i know i must search the forums and i will but thought i should ask since im on the subject plus my posts counts suck..lol

The spring pin is right in front of the mixture screw. unless its been taken out.

just try backing it out a little at a time and make sure u know where it was incase it doesn't go well, count your turns. as for a weber, I got the 38 but many recommend the 32/36. depends on the person. the 38 is better if u plan on doing any minor engine upgrades.