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Old 03-17-2013, 03:49 PM
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Popping or misfiring exhaust note.

I have a fairly stock chevy 350 with a mild cam, headers and edelbrock tri-power manifold with three rochester two bbl. Carbs.
I was running a mallory unilite distributor and burned the module out while starting the car with a charger hooked up. Just to get the car running to check things out, after sitting for ten years, i put a points type distributor in and it fired and ran ok. Now, for some unknown reason it wants to pop through the exhaust and sometimes back through the center carb.
I've checked the timing , changed the cap, and made sure the firing order was correct, but still have the problem.

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Old 03-17-2013, 05:35 PM
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How long did it run 'good' before it started popping?
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Old 03-17-2013, 06:01 PM
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What rpm is it popping at? Have you looked at all vacuum lines for cracks? Are the carbs flowing fuel? Inspected the cap and rotor for cracks/carbon tracking?

Sounds like point float or a lean condition maybe. Take a look in the float bowls for jelly like material (ethanol by-product) or sediment. Fuel tank strainer clogged? Fuel Filters? Old fuel?
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Old 03-18-2013, 11:16 AM
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The pop is mainly at idle but disappears as the eng. Temp gets warmer. Just rebuilt all of the carbs , replaced the cap. Fuel is new but the car sat for ten years . When driving it hesitates upon acceleration and dies when coming to a stop.
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Old 03-18-2013, 11:30 AM
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Pop at idle and goes away when warmed up..... could be plugs. Hesitation and dies.... could be one thing or combination - what is your timing at (would help to know specs of cam), float levels, pumps not set right, leaks (such as throttle shaft is loose), butterflies not adjusted correctly. Hesitation could be not getting enough shot of gas - sometimes comes with a pop through the carb. Does it hesitate and then pick up or do you need to let off the gas? Give details... we are not there to experience what you have going on.
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Old 03-19-2013, 02:33 PM
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Sbc popping exhaust

The plugs were a little wet with some carbon build up, timing is at 8 degrees btdc , when i open the throttle it hesitates and then picks up sitting or in motion. I don't need to lift off the gas for it to pick up. It ran so so for about two fire ups and then the popping started . Float level is 1 5/16" drop is 1 29/32" . When run at wot driving, it runs like a raped ape. Don't have cam specs, but when it ran ok it had a very smooth idle.
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Old 03-19-2013, 03:44 PM
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Bump your initial timing to 14 and limit total to 34-36. This could make a big difference. You need new plugs. You should have good hot iginition instead of points. It probably ran ok at first, but the plugs fouled out and now runs bad. Points may not be enough. Start there and make sure your carbs are not flooding over.
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Old 03-20-2013, 01:26 PM
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Make sure #5 and #7 is not backward. May need a hotter plug. Check carbs for internal gas leak.
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