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Re: Stressed Engine Components

To: triumphs@autox.team.net
Subject: Re: Stressed Engine Components
From: Bob Lang <LANG@ISIS.MIT.EDU>
Date: Fri, 23 Jul 1999 10:07:12 -0400 (EDT)
Hi,

I need to chime in, albeit a bit late, to make sure that at least someone 
touches the following points.

If you are concerned about the integrity of the main journal bolts, you 
can have them tested, crack tested or x-rayed and measured, but this is 
probably overkill on a street motor of any sort. Believe it ot not, on 
the TR6 anyway, the way the main caps bolt into the block is a pretty 
strong setup, what with the two hefty bolts and the "shoulders" of the 
"saddle" resting on the block in a "clearance" fit.

Frankly I wouldn't worry about the main bolts. Unless you've had a 
"problem". In which case everything is probably toast anyway, but if not, 
I'd be leery of used main cap bolts from a trashed motor.

Now the rod bolts, that's another matter.

Yes, you can re-use them with success. But you need to inspect them 
carefully. The rod bolts are probably the second-most-stressed component 
in your engine. They do stretch. You can measure the stretch. If they are 
not streched, you can re-use them.

If you elect to buy new, keep in mind that you can buy them from the Big 
Three, but as Grasroots Motorsports Magazine reported in the latest 
"junkyard" article, you can buy x-rayed rod bolts from the reputable 
tractor dealer like Catapiller. I know there are some Deere employess on 
the list, I'll let them chime in if Deer winds up having anything like 
x-rayed rod bolts suitable for Triumph engines. At any rate, I bring this 
up because reportedly there is a significant cost savings by using the 
CAT bolts, and they are x-rayed... this is a double win.

As a point of reference, the list TRF price for a rod bolt for a TR6 is 
5.95. If the CAT bolt costs 5.00 - it's still a deal.

All the above points do refer to TR6 (and Vitesse and GT6 and 2000/2500 
Triumph in-line 6's). I have no idea about TR3 and TR3 except to say that 
the list price of those components seem to be about 30% greater than the 
sixes.

That is all. 
rml

p.s. and the "most-stressed" component in the motor?? IMHO the cam and 
lifters. Those babies take a pounding!!!
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