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Discussion Starter #1
recently bought a 79 fsb 351 rebuilt recently, i keep fouling plugs have changed plugs, plug wire,napa brand change carb runs about for a while then fouls 1 or 2 clean and there good for a while. any ideas
 

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Fouling them with what, oil? If it is oil, pull a compression check on all your cylinders. If you have one or two that are low on compression, you probably have some bad rings. Valve seals may be bad also, this will not show up on a compression check but a lot easier to fix then bad rings.
 

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Then I would say it's bad wires or you might have a couple of crossed wires. But if that was the case, then the truck would run rough or back fire. Also check you cap and rotor.
 

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couldn't a rich air fuel mixture foul your plugs as well?
 

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Yes it will, but are both plugs on the same side of the engine? If so which ones? The stock 2 bbl carb is split to feed 4 cylinders on one side and 4 cyliders on the other side. I do know that Ford originaly had the plug wires routed a certain way to prevent cross firing of the plugs. I don't think this holds true these days with the better quality of plug wires that are on the market.
 

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Discussion Starter #7
thats what i was thinking was it being the air fuel mix i have a new cap on i was also wondering if it could be the wires anyone else have problem with napa brand ive already had to take ane set back for breaking the metal from the wire
 

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I am not familiar with the brand of wires you were referring to,but you can't just grab the wires and yank on it, the wire will separate from the little metal piece. You have to grab hold of the boot, preferably using those spark plug wire pliers to yank it off.
 

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Discussion Starter #9
thanks everyone got it fixed carb needed adjust a little more. what should a stock 351 compression be mines 150
 

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150, acroos the board, (give or take a few pounds) sounds pretty darn good to me
 
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