ORIGINAL: Semisane

Note that the flash hole on the Mustang plug - though almost twice the diameter of the Omega plug - is almost
four times longer.
Now I'm wondering if I'll ever get Blackhorn to work well in the Mustang. Hey, maybe that's a good thing.
Just drill about half way thru the plug , from the primer side, with the 1/8 drill bit and you'll be all set I'd say

Use some 3-in-1 oil as you drill it out, for a good smooth cut


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And keep the plug fastened tight, BH209 needs a nice tight seal all around.
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