My 1966 Chevy C10 has a 350. It idles good but starts to backfire through the carb when throttled up. Changed dist, carb, plugs, wires. Compression is good and checked fuel pump and it still does it. It has a new timing set. What is the likely cause?
by 
lwrdrchevs
ANSWERS: 9
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New timing set you say but is the timing correct? Check the rotor and cap in the dist. and make sure it all lines up. This seems like a mystery to me. Have you had the block inspected? The wiring harness? Fuel lines? I'm grasping at straws here. All the best, Good Luck
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i had a similar problem with my 350 just the other week,it turned out to be a faulty carbon pin in the top of the dizzy cap,the spark was very illregular.this also makes the timing seem out,check that the plug leads are on in the right order,remembering that number 1 is front left of engine,l/h side is 1,3,5,7, front to back, r/h side front to back 2,4,6,8,
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check for worn camshaft. very common with chev. small block.
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if your dist. has points the gap is not correct or your timing is off. good loock.
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check the valve springs, spark plugs, & cam...according to the 2 mechanics running around my house trying to get my postal vehicle fixed, it is prob one of the 3.
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i agree with geek . Timing. bring engine up to top dead center check the rotor in the distributor and see if its pointing to the #1 plug wire on the cap. If its pointed wrong take the distributor out and reinsert it so that it s pointed correctly. Besure your tdc on the powerstoke not the exhaust stoke. Start ur engine reset the timing. Disconnect the vaccuum line to the distributor when timing the engine if u have the old style dist. You may just have the timing way to far advanced. Using a timeing light might give u some clues. This is what I would do hope it helps.
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Backfiring through the carb usually means the timing is off. This happens because the fuel mixture is being detonated while the intake valve is still open and it backs up through the intake and out the carb. Definitely a timing problem, probably off 180 degrees.
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hopefully you lined up the gears when you put the chain on when you installed the new timing set. if thats off you''ll never get it in time. if you try all the other suggestions then the only thing left to do is to take the timing cover off to check to make sure the set installed is timed correctly. good luck.
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have u tried new points and new condenser? if not, try that before you yank the timing cover.
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