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Old 05-06-2020, 10:11 AM   #6
MikeK
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Join Date: May 2010
Location: Windy City
Posts: 2,919
Default Re: Good Spark Plug for a Brumfield 7 to 1 Head

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I also have a Brumfield Super head. My compression ratio is higher than yours, though. About 8:1, my cranking compression is 155-160 psi. The W14's run well in mine. If your head is fouling W14's, even at just 7:1, you may have other issues:

1) Running with a too rich carb. Do you have a lambda meter?
2) Your current cam is a bad match for the head/CR.
3) Dizzy body or ignition system causing a lot of misfire while cruising.
4) Late timing. (With 7:1 or higher you cannot just leave the advance lever alone- you kind of need to think like a vacuum advance as conditions change.)
5) Tired rings. Do a compression check. With 7:1 you should see at least 115 psi.

Note: For those casually reading this string, a Brumfield Super head is a completely different head than the Brum 5.9 head. Plugs that run well in the standard Brumfield will perform differently in the the Super head. It has considerably shallower chambers creating a somewhat different flow pattern, a lowered and re-positioned spark plug, and spark plug gasket seats that are recessed into bored holes well below the top of the head. This last issue makes some plugs nearly impossible to use if the hex is at the gasket face, as there is no room for a socket to get that far down the recessed plug wells. An option is to use 18mm to 14mm reducers and run extended length 14mm plugs. Platinum tipped plugs, anyone?

Last edited by MikeK; 05-06-2020 at 11:14 AM. Reason: I'm getting dyslexic!
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