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

[jpaynepbr at cox.net]

I had a catastrophic driveline failure on a TR3 a few years back – ring and pinion ate itself and locked up.. transmission ate 2nd gear on main and layshaft and…….front main bearing bolt on manifold side of motor sheared.  This in turn cracked the block vertically between the hole for the main bolt and the front manifold side stud.  I imagine the entire driveline being “whipped” from rear to front.

 

Even though we were able to get the broken bolt extracted, the block was junk.  

 

Similar thing happed (motor only) on a friends TR2 powered Morgan.  Ken Gillanders was able to salvage that one.

 

From: Triumphs <triumphs-bounces at autox.team.net> On Behalf Of Dave Connitt
Sent: Monday, December 13, 2021 2:27 AM
To: Guy Huggins <guy.huggins at icloud.com>
Cc: Triumph Mailing List <triumphs at autox.team.net>
Subject: Re: [TR] 1965 TR4A - Looking to drill out a stud hole in block. Need recommendations on a drill guide/jig.

 

Hello Guy,

That is a tough one. Have you considered talking this over with  the machinist that did your cylinder head as he may have come across this type of issue before. I agree with you that locating and holding the X, Y and Z positions of the repair is critical. 

Best of luck to you.

Dave Connitt 

Sent from my iPhone





On Dec 11, 2021, at 6:35 PM, Guy Huggins <guy.huggins at icloud.com <mailto:guy.huggins at icloud.com> > wrote:

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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