I think I'd try a bottoming tap first. You'd have to make a super long one,
but that's not too hard. Maybe drop a thin pilot in and drill a little deeper.
The pilot would keep the drill from thinning out the existing threads. I have
no idea how close to breakthrough they took these holes at the factory, but I
bet there's some kind of margin, and I'm not sure what the problem would be
with breaking through anyway. If you could pick up a half inch of thread room
you'd be in pretty good shape. Perhaps if you DID drill through you could
helicoil from the inside. Or just get a good block and have at it.
On Apr 25, 2010, at 2:24 PM, M&M Hado wrote:
> Thanks, Bob & others who sent comments.
>
> One idea was to get an oversize stud, at least on one end, and helicoil at
> the top of the block and use a short stud. I wouldn't want to enlarge the
> hole in the head though so this would be a custom stud with different sizes
> on each end.
>
> If there were only a few threads engaged the first time around, maybe
> cleaning up the bottom of the hole and chasing the treads might get enough
> bite to try again. It's in an engine stand so access is good. He's going
> to try this and if that fails, he already has found another head. That's
> probably his best choice anyway.
>
> Mike
>
>
> -----Original Message-----
> From: Bob Kramer [mailto:rkramer3@austin.rr.com]
> Sent: Sunday, April 25, 2010 8:58 AM
> To: M&M Hado; fot@autox.team.net
> Subject: Re: [Fot] TR4A Stripped Threads in Block
>
>
> I had one block were a previous owner must have done the same thing, I
> couldn't get two studs to turn. The one in the front was easy, I could see
> that a hole had been drilled and tapped from the side of the block an I was
> able to get the set screw out after much effort. The long stud was harder
to
> identify and I finally figured out that the guy had drilled through the
stud
> hole into the bottom end and tapped that hole to match a threaded hole he
> created in the long stud. After all that I junked the block because I have
> spares, but if this is a restoration this technique would probably save the
> block. Truth be told, if I just knew about the locked down studs before I
> manhandled them trying to get them out I probably could have easy-outed the
> set screws, or just left them alone.
>
> Bob Kramer
> Volente, TX
>
> Perfection is not attainable, but if we chase perfection we can catch
> excellence.
> Vince Lombardi
> ----- Original Message -----
> From: "M&M Hado" <mdhado@comcast.net>
> To: <fot@autox.team.net>
> Sent: Sunday, April 25, 2010 7:41 AM
> Subject: [Fot] TR4A Stripped Threads in Block
>
>
>> A friend just stripped one of the long cylinder head stud threads in the
>> deep hole when the torque got to 90 ft-lb. It was hard seeing a grown man
>> cry. My first thought is that the block is toast. I'm sure he's not the
>> first so are there any suggestions for a fix? It's a street TR4A.
>>
>> Mike
>> _______________________________________________
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>>
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