Hi guys
I have been dealing with this problem for so long. The engine backfire through carb on hard and sudden acceleration.
I had a carb tuner, to tune the qudrajet. have new chip, capacitor, spark plugs, wires, rotor. But the problem still insists.:(
Also when the engine is cold I hear some little explosions in the exhaust as well.
The ride is runing rich and smokes as well.
I am sure this is due to one problem only... and PLEASE HELP ME...

Are you running any kind of MSD box or anything? Mine does this when my battery gets low. Not supply enough power to the msd box and it pops and fires in the exhaust.

If you don't have a msd box, look at your grounds engine and chassis. Might have something there a miss or just need to be cleaned up.

Are you running any kind of MSD box or anything? Mine does this when my battery gets low. Not supply enough power to the msd box and it pops and fires in the exhaust.

If you don't have a msd box, look at your grounds engine and chassis. Might have something there a miss or just need to be cleaned up.

NO, MSD... it's just the stock HEI
Also the Ground is provided to block (attaching the battery by a thick cable to chasis and alternator) ...

I am doubting on valve function....:mad: can it be,,,,

What is your timing set at?

Timing, carb tuning and timing is the biggest problems when getting these things to run right.

What is your timing set at?

Timing, carb tuning and timing is the biggest problems when getting these things to run right.

Does a little (2 or 3 degrees) advance or retard timing make symptoms like this: I mean engine coughs and bogs like hell,,,,,

I mean engine coughs and bogs like hell,,,,,

the secondaries may need adjusting sounds like they are flopping open too fast. Try tightening them up and see what happens.

The carb is great....it's tuned. What can be the problem except the carb for backfiring?

Valve problems???

can it be valve lash problem?

If it's out of adjustment or clogged you may be lean when the throttle plates open. You'll figure it out. Just noticed it's running rich...Try to borrow a carb from a friend for a half day and isolate it to the carb if you can.

okay this might be the problem as i had the same thing somewhat happen to my camaro . i had a bad alternator that was grounding out the electrical system and everytime i tried to accelerate it would backfire and almost want to die/shut off . also sticking advance weights on a GM HEI if that's the distributor you're running will cause those symptoms

can it be valve lash problem?

valves can cause backfire through carb, but early stages may be a spitting or sputter rather than backfire.

I would also check the choke as well. Running rich may be a good indication that it is being choked. That would also be a good indication of the backfiring through the carb.

I am assuming you have an elctric choke.

1st make sure you have 12 volts at the choke connection with the ignition on.

2nd I would make sure the choke is functioning. I am not sure how you do this, but I know replacing the choke cost about $40 from Advance autoparts and about 15 mins of my time.

valves can cause backfire through carb, but early stages may be a spitting or sputter rather than backfire.

yeah I was actually searching for the exact word (spitting or sputter) that's it... the flames gets out of the carb on sudden full throtle and overal engine malfunctioning (same symptom as wrong firing order)
any other idea now?