The plastic shim you mention is probably a product called Plastigage
(sp?). It's a little thread of soft plastic that gets smashed between the
bearing and the crank. You do this by pulling off the bearing cap,
putting on a 1/4 inch piece of Plastigage on the bearing surface then
replacing the cap and tightening it down. The amount that it's spread out
after you pull the cap off and look at it tells you the bearing clearance.
I don't think it could be done correctly while the engine is in the car,
given that the weight of the crank would be pressing downward in the
direction you're checking the clearance.
Your easiest indicator of the need for new bearings is low oil pressure,
but even before that, you could take off the bearing cap and just look at
the surface of the bearing. If it's scratched or worn, it needs to be
replaced.
John Middlesworth
1966 TR4A
On Wed, 16 Sep 1998 sanborn@net1plus.com wrote:
>
>
> I have solved the advance timing on my TR4... but I beleive that problem was
>just calling attention to a bearing problem. The bearing problem could have
>been caused by years of driving with the detonation problem by the PO. Either
>way... I have an engine that VERY sensitive to timing and it makes a very
>nasty marbles sound before the oil gets up to the bearings when it is started
>cold. Once the oil is up.... there are no bearing symptoms except the timing
>advance sensitivity.
>
> Does any know about some standard test procedure for testing whether your
>bearings need replacing? I was on the TRF tech line and the guy talked about
>this but never explained it. He spoke as if you pulled the pan and slipped in
>some sort of plastic shim... I really didn't get the jist of it.
>
> Also... does anyone know of a source of advice on TR4 engine rebuild
>procedure. There is an MGB video available but can't find anything in the
>how-to style on TR2/3/4 engines. I know how to do a generic rebuild and have
>direct experience... but each engine has its unique quirks. One thing I would
>love to have is "rebuild Parts List"
>
> Can you guys that have do share your experience.
>
>
>
>
>
> Brian Sanborn
> 62 TR4 CT16260L Groton,MA
> sanborn@net1plus.com
>
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