On Sep 27, 12:24*am, "Dave Plowman (News)"
wrote:
In article ,
* *The Natural Philosopher wrote:

I had to fit new big end shells and main bearing shells to a Rover V8
engine about ten years ago.

Only the worst of ignorant ****s would fit new bearing shells to
anything. If the shells need replacing, the bearing surface is also
worn/damaged.

No.
Crankshafts are hard steel,. bearing caps are IIRC lead indium plated,
they wear much sooner.

Fallacy. And I thought you knew something about cars.

If you let them wear to the coppper backing of course you WILL score the
crank.

And copper is harder than hard steel?

Having rebuilt more engines than I can remember in my time, I've never
found a case where replacing shells only when there are signs of bearing
problems works. Only time I'll replace bearing shells without a crank
grind is when carrying out other work which requires splitting the
bearings. Because they are cheap, it makes sense to replace them - in much
the same way as you fit new gaskets.

In the bad old BMC days I used to replace big ends at 30k, mains at 60k
and have a bloody good look at the crank and bores at 120k, if the whole
car lasted that long.

You replaced them on spec - or when there was signs of wear?

--
*Life is hard; then you nap

* * Dave Plowman * * * * * * * * London SW
* * * * * * * * * To e-mail, change noise into sound.

With shell bearings, there are two forms of "wear". Hard particle
lodge in the soft metal and the shaft wears.
OR local overheating causes the shell to distort increasing the
clearances unacceptably.