Thread: backfire after shut down

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hey guys iv just gotten my 327 sbc running after replacing the heads, cam and carb. Iv tuned it by ear as best i can and i have it running pretty good. There is a off idle stumble, but other than that it runs great until i shut it down then about 1-2 secounds later a loud backfire. i believe it is through the exhaust although there is a white smoke in the carb. where should i start looking?
thanx john

Sounds like the butterfly's in the carb are not going completely shut....

yup... check and see if you have your throttle screw adjusted open too much when you let off the throttle all the way the bottom butterflies should be shut, if they're not, then you're not even idleing on your idle circuit.... which means your timing is probably too far off as well, because you adjusted the throttle screw to get it to run with the timing you've got would be my guess

hmm i did adjust with the idle screw to make it run with the timming i had. damn your good ill go look at that thanx.

ok so all the advise you guys gave me is working im just having trouble getting it to idle now, but im getting closer. i had to move my distributer a gear back becouse i ran out of room turning it and found milky oil so im off to take the top end apart just hoping it is a simple gasket.

more than likely is.... check intake first before pulling heads.... intake gaskets are more likely the point of failure.... and yeah, you'll have to get that timing retarded a little, its probably advanced a bit since you had it in your off idle circuit

yup pulled the intake manifold today and the gaskets are soaked. owell im learning as i go, i believe it is due to the fact that i got my heads milled slightly and didnt do anything to the manifold becouse i eye balled it and thought it was ok, guess not. so ill bring it to the machine shop after the weekend and see what they reccomend. thanx again for the info ill try to keep ya informed.
john

i used felpro gaskets the ones recomended by afr but i cant think of the amount i had milled out of the heads right now but i do remember the machine shop guy telling me that the intake might need to be milled. but ill try to find or think of the amount i had milled tommaro. sry for the grammer late party night post.