Need help with exhaust backfire

[yellowblazer1969]

When i crank the blazer it runs fine but whan i try to drive it and accelerate it backfires out of the exhaust. I am not sure if it is doing it out of both sides of the exhaust. I understand that usually exhaust backfires mean too much fuel is being delivered and it is igniting in in the exhaust. Can anyone tell me what to adjust on the carb, is it the screws or the return spring. Could this be caused by anything else?

Thanks, chris

[siksilverado]

HAVE YOU CHECK YOUR TIMING SPARK PLUG GAP AND CONDITION INCLUDING CABLES CAP AND ROTOR TOO VACCUM LEAKS OR THE VACCAUM ADVANCE

[yellowblazer1969]

Originally Posted by siksilverado

HAVE YOU CHECK YOUR TIMING SPARK PLUG GAP AND CONDITION INCLUDING CABLES CAP AND ROTOR TOO VACCUM LEAKS OR THE VACCAUM ADVANCE

I set the timing replaced the plugs and gapped them replaced the wires, fairly new cap and rotor on a mallory setup without vac advance.

thanks, chris

[lks dcvn]

In my case it was an exhaust leak at the manifold/exhaust tube that caused the backfire.

Upon rapid acceleration and then taking my foot off the gas would lead to a nasty backfire and if I let my foot off the gas slowly - it would be less likely to occur.

I ended up replacing my manifolds and the entire exhaust - but the leak I had that caused the backfire was between the manifold and the exhaust tube(s).

Good Luck!

[unclewatts]

This may not be it but a bad coil can cause backfiring.