Thread: Exhaust backfire, carb related?

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i've never had any luck with reman carbs from parts stores.... i've pulled them apart and found that the jets are different sizes, parts are missing, parts are installed wrong, and my favorite, they're missing a screw so they just JB weld it together.... in the shop its gotten to a point that i just make customers buy brand new carbs or get the one they have rebuilt... which i send it out to FSP they swap out a rebuild of the exact same carb or updated model of the carb.... and i've never had one come back with problems

Southerner--

I thought of the vacuum leak too. Didn't find any. Where are you going with the distributer thing? I was just in it yesterday checking things out, and making sure everything is as it should be. Are you saying I should be looking for something else???
I agree with you on doing things right the first time, I was just jabbing at myself a little with the comment about doing something for peanuts.

Originally Posted by 65ny

Southerner--

I thought of the vacuum leak too. Didn't find any. Where are you going with the distributer thing? I was just in it yesterday checking things out, and making sure everything is as it should be. Are you saying I should be looking for something else???
I agree with you on doing things right the first time, I was just jabbing at myself a little with the comment about doing something for peanuts.

Yup, sometimes the distributor advance mechanism sticks due to old sticky grease and oil or grit, rust or a spring has become worn or is broken, missing.
What happens is that the advance can stick at differnet degrees of advance, this changes the engines habits at idle or in the higher revs. You adjust for one lot, go for a drive come back and it's "off" again. Does have the potential to drive people bannanas because of the constantly changing circumstances. So check your advance manually as described. Then if you have a timing light, hook it up disconnect the vacume advance and plug it, point the light at the timing mark on the balancer and bring the revs up on the motor say to 1800 rpm The timing mark on the damper should advance (walk up ) smoothly, if it doen't and/or jumps around you know you have a problem with the distributor. Oh and when you take the revs back to idle the timing mark should be back down to where you set it.
Good luck with it. MIke

I'm going to point this out again. If you can turn the idle adjustment screws in and it doesn't make any difference, your throttle plate is open to much.

like mike said, sounds like a vac. leak, or what Mikej said, if it is you can put all the carb. on you want to and still have the problem, unless the leak is the carb. the mikes has the last say on this one. three mikes cant be wrong.