Hello all, just signed up in the hopes one of you can help me out with this issue.

I have a 84 chev with a 350 in it, carbed. I bought it 9 months ago and put a brand new carb on it 3 months ago, been running great since then.

My issue started last week on a drive to work about halfway(10 miles into drive right after it fully warmed up) it started backfiring through the tailpipe with moderate or higher throttle applied. i could use about 20% of the pedal with no backfiring but then if i pressed it for some power it would backfire and miss. Turned out i had a loose spark plug wire so i snapped it back on and it worked fine for the remaing 8 times i drove it to/from work that week.

Now today on my way to work it started backfiring again, but this is the wierd part it now only does it at LOW throttle, anything below half throttle it will backfire like crazy, much worse that last week. Last week was like a light pop every 2-4 seconds. This time at anything below enough pedal to engage the secondaries in the carb it backfires like crazy, really really bad much louder than last week. Literally sounds like i have a popcorn machine under my feet when it happens. But if i tromp on it it will run fine all the way up to 5500rpms no backfiring no issues, im just getting tired of leaving 20 feet of rubber at the stoplights so i would like to fix this issue.

A buddy said he though it was the fuel mixture on the carb but i dont think thats possible as at idle or in neutral it will rev up fine all the way to redline with any amount of pedal being used with no missing or backfireing.

I think its ignistion related and am leaning towards a distributor rebuild but let me know what you guys think.

Also timing is set to 12 degrees at the crank so it should be fine too.

 

12 degrees is too much 4 would be better but that woulodnt cause a backfire. Does this unit have an air pump on it? If it does take the belt off and try it.

 

I assume this has electronic ignition. What has changed as at least as far as the carb goes? I had an 82 that had some issues with the distributor, but taht means it just won't run. What if anything has changed?

 

Buy a vacuum gauge and read THIS

 

Hello, I have a 2001 Silverado 8.1 Litre Engine...has only 30,000 miles on it. It was firing up on the dime, first click, boom, right up. then I ran it out of gas. Now, it cranks and cranks before firing. If I turn the key right off and turn it again, she usually fires right up. I tried bleeding out the schrader valve, but didn't find any air. Some times when I try and start it repeatedly one after another, she backfires.