What is the thread size of the dizzy clamp down bolt. I know it has a head that is 7/16", but I can't figure out what thread it has. Thanks.

Never mind. I got it.

1/4-20 ??? 1/4-28 ??? Do tell...

I used a valve cover bolt. My problem was the bolt wasn't going in right. I pulled down the brace that has the hole in it for the bolt, to get it below it. I screwed in that bolt, and could see it fit. After moving it back up, I had to turn that brace a few times, so I could line up the bolt straight. I finally got it that way. So it is the same size as the valve cover bolts, whatever they are.

Yup, 1/4-20.

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1/4-20 for earlier engines (pre 80s?) and 5/16-18 for later engines.

I don't know the cutoff year, but somewhere in the late 70s, I believe. I have a couple of cast crank blocks and they are 5/16-18.

Lou

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