Author Topic: first time CARB backfire :(  (Read 2940 times)

Offline txchainsawgogi

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first time CARB backfire :(
« on: March 18, 2011, 09:13:12 pm »
i recently changed the exhaust system to headers and dual exhaust pipes, i've been re-tightening all the bolts after every trip. i also recently rebuilt the carb and changed the plugs to a different, cooler range.

it was running great all week, very smooth response and smooth idle... in neutral and in gear.

today on my way to work it was driving rough, according to my new tach it was actually a bit higher in rpms than normal.

on my way home from work i tried starting it and it popped out the carb. not a lot of smoke but it was still there. waited a good ten minutes and started it again, just fine.

got home and tightened where the headers meet the exhaust pipe, they were pretty loose on the driver's side.

what im thinking is that i have a bit of an exhaust leak at the gasket between the flanges.  sound about right?

Offline mats1985gmc

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Re: first time CARB backfire :(
« Reply #1 on: March 18, 2011, 11:27:24 pm »
check your timing. an exhaust leak shouldnt make it back fire in the carb

Offline Lt.Del

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Re: first time CARB backfire :(
« Reply #2 on: March 18, 2011, 11:47:37 pm »
you sure it backfired thru the carb?  an exhaust leak will cause a backfire if the pipes are hot and there is raw fuel coming thru--hits the oxygen and boom! 

If it was carb backfire, i agree with Mat.  Something else beside exhaust.  carb bolts tight?  any air coming in from under the carb? Timed right?

Offline txchainsawgogi

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Re: first time CARB backfire :(
« Reply #3 on: March 18, 2011, 11:53:29 pm »
def not timed right, but its just never done it before. I didn't think the timing was that bad.

Offline 1979C20

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Re: first time CARB backfire :(
« Reply #4 on: March 19, 2011, 12:19:01 am »
Make sure you check your accelerator pump for functionality. It can break from a carb backfire
1979 SCLB C20 Q-jet 350 SM465 14b F.F. 4.10 G80
1989 GMC Suburban V2500 TBI350 TH400 4in lift 35's 14b SF