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post #1 of 8 (permalink) Old 08-17-2003, 11:24 PM Thread Starter
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carb backfire

could a blown powervalve make my car backfire thru the carb when i punch it? i just got my 460 up and runnign and everytime i step on it hard when there is a load on it it will backfire, i am stumped as to what the problem is, i know it is in the carb because i borrowed my buddies 750 demon and it ran like a raped ape, my carb is a 750 vac sec holley so any advice wahtsoever would be grewat, i thought it might have been in teh timing but i just went thru the timming and i have it set at about 12 initial and 26 degrees of mechanical advance, this is a stock 460 with headers, a weiand intake and a comp cams 280 in it.

[ This Message was edited by: aaron on 8/18/03 11:24am ]
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post #2 of 8 (permalink) Old 08-17-2003, 11:35 PM
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carb backfire

Hi
Also check the carb mix screw's might be a lean pop. and check float level.
Tim

64 International 4dr. truck w/466 14.5 1/4 @ 93 mph.
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post #3 of 8 (permalink) Old 08-18-2003, 12:12 AM Thread Starter
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carb backfire

well i havent really drove the car, just enough to experience the backfiring but the plugs are black which indicates a rich condition, but it idles alot so i think the idle screws are kindof rich so i figured the problem wasnt in the screws but i too thought and still do think its a lean backfire. i will have to check the float levels tommorrow


[ This Message was edited by: aaron on 8/18/03 12:13pm ]
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post #4 of 8 (permalink) Old 08-18-2003, 07:55 AM
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carb backfire

If you did'nt have a blown power valve when you started it you probably do now. Holleys are notorious for blowing power valves after a couple of backfires.

I suffer from CRS....Wait what?
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post #5 of 8 (permalink) Old 08-18-2003, 09:04 AM
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carb backfire

I would take a good look at the timing.Have
you done anything to the dist.weights or springs?
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post #6 of 8 (permalink) Old 08-18-2003, 10:03 AM
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carb backfire

Sounds like the squirter is way too small. If it backfires like that it is most likely from being lean right after you floor it. What size squirter is in there? Should be stamped on it right between the two nozzles. I'm guessing you have about a 31 or 35. I would try bumping it up a few sizes to see what that does. A really good investment is the Holley accelerator circuit tuning kit which has a bunch of different squirters and pump cams, vacuum springs, and pump diaphragms. Really helps to dial things in.

BTW a blown power valve will pretty much just make the engine run way rich at idle and that is all.

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[ This Message was edited by: Revolutionary on 8/18/03 10:04pm ]
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post #7 of 8 (permalink) Old 08-18-2003, 06:08 PM Thread Starter
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carb backfire

where can i find a place that sells all the holley ktis i will need. I was thinking the squirter was too small also but I didnt know they were adjustable, i am new to carbs
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post #8 of 8 (permalink) Old 08-18-2003, 07:39 PM
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carb backfire

Speed shop or go online to Summit or Jegs.

I suffer from CRS....Wait what?
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