Saturday Night Racer - Backfire thru carberator

Hit n run LMR Member Offline Dirt Late Models Rule! Posts: 161	Backfire thru carberator 04/11/10 at 6:54pm When i rev up my engine it started backfiring thru the carb. Checked the timing.plugs and wires,changed the power valve,everything looked OK inside the distributor. Any suggestions or similar experiances ?
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imracin68j LMR God Offline Do the impossible Posts: 6228	Re: Backfire thru carberator Reply #1 - 04/11/10 at 7:24pm cam timing?
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Hit n run LMR Member Offline Dirt Late Models Rule! Posts: 161	Re: Backfire thru carberator Reply #2 - 04/11/10 at 7:29pm The problem started after a few laps into hot laps.The car has not been used for the last year, but before that it ran great.
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OLD SCHOOL#6 LMR God Offline CHEVY RUMBLE !! Posts: 2452	Re: Backfire thru carberator Reply #3 - 04/11/10 at 7:40pm Possible sticky or bent intake valve, possible weak or broken intake valve spring ...................
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Hit n run LMR Member Offline Dirt Late Models Rule! Posts: 161	Re: Backfire thru carberator Reply #4 - 04/11/10 at 7:48pm The engine runs a little ruff at idle and has a misfiring cylinder.Also you can hear a poping echo sound every few seconds thru the exhaust.
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Andrew LMR God Offline 2006 SMS M.S. champion... more of a PB these days Posts: 1359 Camarillo	Re: Backfire thru carberator Reply #5 - 04/11/10 at 7:51pm Do a compression test, I'l bet you find which cyl is weak, then check the valve springs before you tear it down.
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Hit n run LMR Member Offline Dirt Late Models Rule! Posts: 161	Re: Backfire thru carberator Reply #6 - 04/11/10 at 8:06pm I have considered changing the carb and or distributor.
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miniguru27 LMR God Offline Dirt Late Models Rule! Posts: 652	Re: Backfire thru carberator Reply #7 - 04/12/10 at 10:27am I would try checking the valves the springs.and the cam to make sure there is not a flat lobe.Just an idea.
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brummi5050 LMR Rookie Offline Posts: 61 Nipomo,CA	Re: Backfire thru carberator Reply #8 - 04/12/10 at 11:26am Rev it up a little to where its popping back through the carb and pull 1 plug wire at a time till the noise goes away. Exaust lobe or valve bent.
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Hit n run LMR Member Offline Dirt Late Models Rule! Posts: 161	Re: Backfire thru carberator Reply #9 - 04/12/10 at 8:23pm Thanks for all the suggestions,I decided before looking at the worst case stuff first to look at the simple stuff one more time.When i looked at the firing order i found #6 and #8 were in the wrong order.Hopefully the misfiring did not cause any damage to any other parts. Thanks again for the suggestions.
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Andrew LMR God Offline 2006 SMS M.S. champion... more of a PB these days Posts: 1359 Camarillo	Re: Backfire thru carberator Reply #10 - 04/12/10 at 8:32pm K- keep I- it S- simple S- stupid Good find! I'm embarrassed that I didn't think of that. ALWAYS go through the simple stuff first.
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imracin68j LMR God Offline Do the impossible Posts: 6228	Re: Backfire thru carberator Reply #11 - 04/14/10 at 6:23pm I think I would have pulled the motor down, swapped the cam, bought a new carb and THEN checked the spark plug wires.. but hey, that's just me.
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Hit n run LMR Member Offline Dirt Late Models Rule! Posts: 161	Re: Backfire thru carberator Reply #12 - 04/14/10 at 9:51pm It took a phone call to Dad who said to look at the wires and plugs again. I guess the man upstairs has his way to get us to call our parents when we have not been calling them enough.
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Watchin15B

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Re: Backfire thru carberator
Reply #13 - 04/16/10 at 2:32am

imracin68j wrote on 04/14/10 at 6:23pm:

I think I would have pulled the motor down, swapped the cam, bought a new carb and THEN checked the spark plug wires.. but hey, that's just me.

I don't think thats just you Billy, I think quite a few of us may have done that!! Good job on finding the problem out without tearing stuff up!! I guess some of our parents are smarter then we think lol!!

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DWR DWR DWR DWR

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Andrew LMR God Offline 2006 SMS M.S. champion... more of a PB these days Posts: 1359 Camarillo	Re: Backfire thru carberator Reply #14 - 04/16/10 at 11:03pm My dad is my "phone a friend" when I can't figure something out too. Wish he didn't live so far away. I miss the old guy.
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56HS LMR Rookie Offline Dirt Late Models Rule! Posts: 34	Re: Backfire thru carberator Reply #15 - 04/17/10 at 6:54am I think i'll give dad a call today before we go out to the track.After all the stuff he put up with over the years, everyday should be Fathers day.
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