12-02-2015, 04:43 PM
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#11
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Senior Member
Join Date: May 2010
Location: Canada Where it snows
Posts: 2,058
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Re: Spark plugs
Quote:
Originally Posted by bluardun
I have a 59A stock engine, 6 volts. My question is: Has anyone use a Chevy spark plugs. They both are 18mm threads. The Ford (Champion)
H-10 threads are 11mm long. The Chevy (Champion) J-12 threads are 9mm long. The H-10 porcelain is receded in the head, as the ignitor is flat with the surface of the combustion area. The J-12 the threads are short of bein flush with the combustion surface about 3/32", but the porcelain and ignitor protrude into the combustion chamber about 3/16 of and inch. Seems the J-12 plugs would burn cleaner at slower speeds.
The reason I ask is, the plugs always look black, like the are not firing hot enough, or long enough.
Thanks
Bill Herbert
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18mm thread ??
R
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