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Old 06-02-2008, 12:16 PM
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350 backfiring through carb

- 350, .030 over, MSD ignition, distributor (w/vac secondary) and coil. RPM Air Gap manifold and 1411 carb. True dual exhaust with cats.

- 12deg initial timing. Hasn't run long enough to set total timing.

- Hard to start, takes a lot of cranking and feathering the throttle.

- Noticed fire in the headers before I buttoned up the exhaust when it was running for a few seocnds at a time.

- Now backfires through the carbs and even burns for several seconds in secondaries after killing engine.

I need some help guys. Any ideas?


thanks

stu...
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Old 06-02-2008, 12:24 PM
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Is this a fresh rebuild
Are you sure that the distributor is in correctly, how are you checking initial timng if it wont run.
I would look at the timing, firing order and valve adjustment in that order. Any of the three will give the symptoms you have described

Chet
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Old 06-02-2008, 12:42 PM
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It is a new cam install. I got it to run yesterday for several minutes, albeit at a higher idle than normal. I guess that could have screwed up my timing work. I have checked the distributor and wire order. I will double check valve adjustment, but I'm pretty sure that is OK. Is there an easier way to do the valves than bumping it with the starter? Now that I have the engine buttoned up I can't just turn the crank by hand to get to the next valve.

thanks
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Old 06-02-2008, 01:12 PM
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Valves adjusted correctly? lash to tight...
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Old 06-02-2008, 01:29 PM
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They make oil stoppers that clip over the rocker and have a plastic tip that plugs the oil hole. Then you could do a running adjustment, by backing them off until they make noise, tighten them back down until they just stop making that clacking noise, and then I go 1/2 turn more. You will notice that cylinder run real rough for a few seconds then smooth out as the lifter bleeds off that pre-load.
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Old 06-09-2008, 03:54 PM
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You guys hit it right on. I did another valve adjust and the engine started right up. Not sure how they got that out of whack, but I found some too tight and some too loose. Anyways, it roars now!

thanks

stu...
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Old 06-09-2008, 07:28 PM
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Glad you got it figured out......have fun with it
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