Spark plugs carbon fouling

smittykid

smittykid

Senior Member
I was just talking to a fellow that has a 29 Speedster for sale. He says after about 100 miles the 1st and fourth spark plugs foul. Two and three are OK. It's carbon fouling-not oil. He's running a MIller High Speed high compression head and a Stromberg 81 carb with an electronic ignition. He can't figure out why it is just the first and fourth plugs that foul. Any thoughts or is there anything else I should be asking? Thanks
 
smittykid said:
I was just talking to a fellow that has a 29 Speedster for sale. He says after about 100 miles the 1st and fourth spark plugs foul. Two and three are OK. It's carbon fouling-not oil. He's running a MIller High Speed high compression head and a Stromberg 81 carb with an electronic ignition. He can't figure out why it is just the first and fourth plugs that foul. Any thoughts or is there anything else I should be asking? Thanks
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He might have a vacuum leak on the intake causing 1and 4 to run lean. Then he might have put larger jets in to get it to run on all 4. We would need to know all the things he has done to it, to know where to look.
 
I had the same problem with #1 cylinder only under my Serr-Miller head. I tried everything, nothing worked except very hot plugs fouled in #1 more slowly. The solution was to change the carb/manifold to a Weber 32/36 with new manifold. No more fouling, lots more power now. I think the Winfield SR/winfield manifold was just giving the first cylinder a lot richer mixture than the other 3 cylinders, can't see how but no other explanation seems reasonable.
 
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