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Old 11-05-2019, 08:17 PM   #44
GOSFAST
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Join Date: May 2010
Location: Long Island, NY
Posts: 1,052
Default Re: Spark Plug Protrusion into Head?

I can add this tonight, the total thickness of the threads on these particular Offy heads is .570", when you add the spark plug gasket thickness it's another .065", this gives you a grand total of .635". A plug with a .500" depth is still not really correct, it will run, it's still not the right way to do things.

You'll generally find this spark plug issue only with the Offy's?

Thanks, Gary in N.Y.

P.S. This is why I stated earlier we prefer to use the Edelbrock castings, they are set up for the .750" long reach plugs, this is how it should be on ALL aluminum castings, and they have the lengths right! Sometimes we fire-slot the spark plug holes or flycut the valve pockets but we always compensate for this machining.
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