Stripped thread in cylinder block of 1964 3hp JH 199A

[Monte NZ]

Hi All
The above motor which I am currently working on has a stripped thread in the block.
It’s the bottom head bolt on the exhaust side. Someone prior to me has stripped the thread and to try and fix the problem, has bored the hole through to the exhaust cavity, but now that part is stripped as well.

I would very much appreciate in ideas of how to hopefully fix the problem. The only ideas I can come up with are to put a nut inside the exhaust cavity or rebore the hole and fit a larger diameter bolt.
I had also wondered if cleaning the existing hole out and filling it with JB Weld and then retapping would be an option.

Compression on the top cylinder was 60 and the bottom was 10. I suspect the lower cylinder was only 10 because of a possible leak through the head not being held down properly.,

What I had hoped to do, was make a head gasket, refit the head and do another compression test before going any further with the rebuild.
I can report that the rings aren’t stuck and from what I can see, the bore looks ok.

Interesting to note that someone prior to me had fitted a long reach spark plug giving the impression that the motor was seized when the flywheel way would only turn 180deg each way.

Thanks for any help in advance.

Monte NZ

[frankr]

A helicoil will be your best friend. How have you gotten this far in the salt and sea without them?

[cajuncook1]

Frank has Helicoiled a block of a JW10 3hp for me while back. Worked great!

Cheers,

Cajuncook1

PS. Monte, I sent you a PM

[Monte NZ]

Thanks very much Frankr for your reply and as your comment about the salt and sea, I can assure you that it causes us much grief here in NZ…….I hate to think of the amount of time I have spent drilling rusted studs and thanks Cajun1 for your reply and PM.

Frank,I never thought of a helicoil in that application, so thanks for that suggestion. I have only used them when spark plug threads have be buggered.
The job you did on Cajuns motor has obviously worked well.

Thanks again to both of you.

Monte NZ

[crosbyman]

are we all thinking spark plug helicoils or…. fixing a small bolt thread at the bottom of the cyl head..

It’s the bottom head bolt on the exhaust side.….

Joining AOMCI has priviledges 🙂

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