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Broken Bolt Boss on Original Head

Steven Starkweather

New member
Mar 17, 2023
1964 Coupe Crusty Survivor L75 Original Motor
Hello Men,
While replacing a head gasket on my 1964 coupe, I noticed as I was installing the head bolts a part of the head bolt boss under cylinder 5 had cracked. I friend had been helping me disassemble, and there had been some slipping with the handling of the head – we are getting old, I suppose...

I hadn't noticed the damage until the black silicone had been spread, etc. So I went ahead and torqued all the bolts to spec. The broken boss site seemed to behave exactly like the other 33 bolts but I am concerned that it may shift under working conditions.

Obviously I can run it and gather the empirical evidence, but I thought I would ask the group if anyone has experience with such an injury. I used to live in Tucson, where machine shops are plentiful, and I would love to take it to be mended, but now I live in the middle of the Mark Twain in Southern Missouri, and I'm pretty much on my own here. Will this have the necessary integrity to survive mild cruising conditions?

Any experiential advice would be much appreciated.
Thank you,


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Hi Steven,
Welcome to the CAC. It appears to be a dirty broken surface so I would suspect it may have been cracked before the bolt was removed. The tight bolt was probably holding the piece in place. The head can't shift because the dowels in the deck surface are holding it in place. Since it torqued to spec there is enough shoulder there to seat against. I can't see it creating any problem. If you found the piece, bag it and tag it so you can have the repair done some time in the future should you ever have the head off again. If you couldn't find the piece, It could be that it wasn't there when you removed the head.


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