occasional backfire

[billschroeder5842]

I get an occasional backfire through my carb on my smog monster.

My 400 with the factory Carter, occasionally backfires when I romp on it. This seems to happen at lower RPMs.

Currently the timing is set a 10btc, it pull as super steady 17hg and idles great at 750. It runs pretty smooth.

At higher rpms, the car seems to take everything I giver her.

Any idea?

[Ghoste]

Lean.

[billschroeder5842]

Thanks-I see a sunday project in the making

[billschroeder5842]

Because the car seems to run so smooth,  I'd hate to mess with the rich/lean. I'm not sure which direction to turn the screws to make it more rich?

I noticed that I have the accelerator pump on the middle setting. Would it make a difference if I moved it to the setting that gave it the longest stroke (more of a shot)?

Would that help to eliminate the back fire?

[Ghoste]

Quite possibly. 
I'd try that first for sure.

[A383Wing]

back the mixture screws out (turn left) for a richer mixture...I would start with only 1/2 turn

[c00nhunterjoe]

Ive found that since the switch to eco friendly ethanol fuels, i had to up my jet sizes to mai tain the same performance as i ran on pre ethanol fuels. Try the accel pump adjustments 1st though.

[Dino]

You may need a bit more timing, your vacuum should be higher on that car as well.  Hook up a vacuum gauge and advance the distributor, see what she does.  Mine backfires occasionally when I retard the timing by a few degrees.

Make a note of how many turns it takes to turn the idle screws in so you can reset them if it does not improve.  As soon as the screws stop so do you, do not overturn, light touch is the key.  Turn one screw out about 1.5 turns, then turn it out a quarter at a time with the vacuum gauge attached and go for the higher number, then repeat with the other screw.  You may need to adjust them to make the car drive better even if the vacuum goes down a bit from the top value found.

[1974dodgecharger]

I love backfire.....i can do it when I decrease my nozzle size down....oh yeah BOOM!