[Fot] How many times can you line bore a block?

[fubog1]

 There's no real "spec" on that, much depends on the existing housing bore dimension on the other 2 mains, & how much was taken off initially.If it didn't have much taken off in the initial line-boring, & center & rear housing bores are in limit, it shouldn't change the crank center too much to size the front cap & clean it up... but... if excessive it will affect all points noted, & rear seal concentricity...Heck I've seen engines that were bored so much that the bearing tang groove was too small!
Glen Efinger

    On Tuesday, July 28, 2026 at 06:35:12 AM EDT, tr4racing at googlemail.com <tr4racing at googlemail.com> wrote:   

 Hi Chuck,

the crank is moving upwards from bore action to bore action. Means the piston deck is getting closer to the head each time and also the chain gets loosen more and more because the crank is moving towards the camshaft.
A matter of measurement how far you can go.

Cheers
Chris

-----Original Message-----
From: Fot <fot-bounces at autox.team.net> On Behalf Of Chuck Gee
Sent: Tuesday, July 28, 2026 12:20 AM
To: Philip Gott <vfracing at aol.com>
Cc: Friends Of Triumph <fot at autox.team.net>
Subject: Re: [Fot] How many times can you line bore a block?

I could be wrong, but I don’t think line boring affects that dimension.  I understand it to be making the caps a little shorter then reboring to match the upper diameter in the block.  

Otherwise, a bunch of other dimensions would be goofed up too.

Chuck Gee

> On Jul 27, 2026, at 4:56 PM, Philip Gott <vfracing at aol.com> wrote:
> 
> Or another way to ask the question is “how much misalignment between the crankshaft and transmission input shaft can be tolerated?”
> I had a block completely gone through, including line boring and it ran very well until number one cylinder liner suddenly split. The engine hydro locked and broke the crank and front main bearing cap. I have a new cap; to use it requires the block be line bored again. I’m wondering if anyone else has a similar experience and can tell me either that it worked out well, or that I should throw the block away.
> Thanks as always!
> Phi
> 
> 
> 
> Sent from my iPhone
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