79 backfiring through carb
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79 backfiring through carb
i have a 79 f-150 with a 351W and a Holly 650 4bbl with a edelBrock preformer intake. hei MSD Distributor -
at 1000x RPM idle to 5000 RPM idle it sounds smooth but when you put it in drive and accelerate it back fires through the carb. iv check'd the plug wires and the plugs they dont seem cracked or corroded checked the gaps on the plugs while i was at it .40 on all cylinders re check'd the firing order.1 - 3 - 7 - 2 - 6 - 5 - 4 - 8 its all correct. could it be just the carb? or how do i check for a frozen valve. im running out of ideas what the problem is.
at 1000x RPM idle to 5000 RPM idle it sounds smooth but when you put it in drive and accelerate it back fires through the carb. iv check'd the plug wires and the plugs they dont seem cracked or corroded checked the gaps on the plugs while i was at it .40 on all cylinders re check'd the firing order.1 - 3 - 7 - 2 - 6 - 5 - 4 - 8 its all correct. could it be just the carb? or how do i check for a frozen valve. im running out of ideas what the problem is.
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is there a vacuum line diagram to check if all vacuum lines are in the right places.
this is my first 351W swap. and iv had nothing but trouble and there was a few things that didnt go back the same way as my old 400m did.
this is my first 351W swap. and iv had nothing but trouble and there was a few things that didnt go back the same way as my old 400m did.
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is the carb new or is it older? if you have an older one with a rebuild kit it prob doesnt have the blowout port on it... you may have blew a hole in the power vavle...
valve timiming, weak vacuum advance spring or ignition timing can cause backfires through the carb.
valve timiming, weak vacuum advance spring or ignition timing can cause backfires through the carb.
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it was rebuilt a year ago. but then again i think i need to replace it cause idk what the previous owner has done to it. and its outdated. i now think its the power valve. so i ill go rip it off and break it down and go from there. thanks
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check for vacuum leak around the intake/base of the carb too...if it stays running spray some carb cleaner around the base of the carb and around the intake if the rpms increase you have a leak...
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its not the timing chain or the timing. brand new rebuilt motor. i checked everything and the dist and bug are TDC
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ok now theres bubbles in my fuel filter.. so i ended up following the fuel lines for leaks or cracks i found a line that was beggining to go bad so ireplace it and all the lines from the fuel pump to the tank. but the fuel filter is still bubbling at idle.
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From: Idaho
? is that with a timing light? or what? If you are timing it with the light to 0 its gonna run like crap! It should be 8-10 degrees advanced like Gumshoe stated before. Also when timing it make sure the vacuum advance is unplugged from the Dist...and the hose is plugged! If not your timing will be off