351w Fuel Delivery Problems ? Backfiring
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Joined: Apr 2003
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351w Fuel Delivery Problems ? Backfiring
Hello all. This is my first post.
Here's my question. I have an 83 bronco with a 351w in it. I bought it at a pawn shop for $1200.00 and had some front end work done on it. At the time I bought it it ran (if you want to call it that) but back-fired A ...LOT.
It has a ....lot of mallory items from the distributor to coil to ignition.
I put a new dist cap, rotor button, plugs and plug wires and it calmed down a bit of the back-firing but after only 35 miles of driving it started again. I pulled the plugs and after only 35 miles they are covered in black soot. So I figured the carb adjustment was off (Its a Holley) and drained the oil (stunk of gas) and filter and put in new plugs. Adjusted the carb until the back-firing stopped and it runs better but after only 20 miles the plugs are covered in black soot again and it just doesnt run well.
Does this sound like the carb is shot?
Any help is greatly appreciated.
Here's my question. I have an 83 bronco with a 351w in it. I bought it at a pawn shop for $1200.00 and had some front end work done on it. At the time I bought it it ran (if you want to call it that) but back-fired A ...LOT.
It has a ....lot of mallory items from the distributor to coil to ignition.
I put a new dist cap, rotor button, plugs and plug wires and it calmed down a bit of the back-firing but after only 35 miles of driving it started again. I pulled the plugs and after only 35 miles they are covered in black soot. So I figured the carb adjustment was off (Its a Holley) and drained the oil (stunk of gas) and filter and put in new plugs. Adjusted the carb until the back-firing stopped and it runs better but after only 20 miles the plugs are covered in black soot again and it just doesnt run well.
Does this sound like the carb is shot?
Any help is greatly appreciated.
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Joined: Jan 2008
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351w Fuel Delivery Problems ? Backfiring
Yes, & gas mileage must be pathetic?
You have a flooding carb.
Floats set too high,or too much fuel pressure to carb and the fuel is by-passing
You need to check the floats for their setting first.
You could start from scratch and re-build the carb if you wish.
*Note: We request that user's title their Thread in a way that Best exemplifies the topic.
I changed this one because titles like *Please help*don't cut it.
I hope you find your problem before you spend too much on fuel.
You have a flooding carb.
Floats set too high,or too much fuel pressure to carb and the fuel is by-passing
You need to check the floats for their setting first.
You could start from scratch and re-build the carb if you wish.
*Note: We request that user's title their Thread in a way that Best exemplifies the topic.
I changed this one because titles like *Please help*don't cut it.
I hope you find your problem before you spend too much on fuel.
Hotshot
Joined: Oct 2002
Posts: 18,488
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From: The Big, Oregon
351w Fuel Delivery Problems ? Backfiring
Which Holley do you have? A 2BBL or a 4BBL? What size? If you figure out what model you have, you can get a rebuild kit for fairly cheap from just about anywhere. one common problem with older Holley's is that the power valve blows out if it backfires through the carb. With the engine off, take a look down the carb and see if there is gas dripping in there, or if it looks unusually wet. There is an upgrade available, called a power valve saver, or something along those lines. All newer Holley carbs come with this already installed.
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Joined: Jan 2001
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From: Virginia
351w Fuel Delivery Problems ? Backfiring
If you want to go the cheap route, some of the parts stores in their high performance sections, have bowel gaskets for holleys. And you can buy just the power valve. But I don't know if this will work if you have a factory Motorcraft/Holley. A complete rebuild would be the best way to go.
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