[TR] 1965 TR4A - Looking to drill out a stud hole in block. Need recommendations on a drill guide/jig.

[Randy and Valerie DeRuiter]

Guy-

I don't want to sound too doom and gloomy, but have you ruled out a cracked block at that location?  That is a common spot for one, usually from someone in the past who pulled the engine by the studs. At least I had an engine like that.  If you haven't done so, take a very good look at the inside edge of the threaded hole.  If you see a crack, that helicoil trick likely won't work.

If you are convinced it is not cracked, possibly another solution would be to take advantage of the deeper hole that you've measured and get a shop to extend the threads of a longer head bolt.  One of the inside longer ones might work - then shorten the other end to fit.  The puzzling part is why does the stud cant to the rear - that doesn't sound good.

Randy

________________________________
From: Triumphs <triumphs-bounces at autox.team.net> on behalf of Guy Huggins <guy.huggins at icloud.com>
Sent: Saturday, December 11, 2021 5:28 PM
To: Triumph Mailing List <triumphs at autox.team.net>
Subject: [TR] 1965 TR4A - Looking to drill out a stud hole in block. Need recommendations on a drill guide/jig.

Howdy All,

As part the head gasket replacement project, I need to address a wallowed-out and stripped cylinder head stud hole in the block.
(If you were standing on the manifold side of the engine, it would be the one furtherest to the front, on the manifold side.)

A stud goes in straight up and down until the top of the threads are even with the block, but it wiggles like hell.
As you tighten the stud down further, the wiggle starts to go away, but the whole thing starts to cant back toward the rear of the block.
This make it impossible to slide the head down over the canted stud.

To fix this I intend to install a coiled insert.  (drill just 1/32” oversized, tap, install insert).
I am hoping that someone from the list knows of a drilling jig/guide for the drilling phase.
I know better than to attempt drilling out cast iron without a steadying device of some sort.

Any and all tips and advice are welcome.

The hole is 1 5/16” deep, and the threads of the stud measure 3/4”.
It is basically threaded top to bottom.

Thanks in advance.
I hate it when you have to fix the unknown thing to fix the known thing.


Kind Regards,

Guy D. Huggins
guy.huggins at icloud.com<mailto:guy.huggins at icloud.com>
817.454.6415





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