David,
In the case of BMC "A" series transverse race engines; you have already
exceeded the safe TBO. The problem area is the center main bearing. You may
very well tear it down and find everything is fine. More likely, especially if
this is the first teardown, you will find a lot of wear on the center main.
Hopefully the crank will be OK and you can just put in new bearings and put it
all back together. We normally go three good race weekends before the first
teardown, and gradually work up to five or six if things look OK.
While you are in there, check the oil pump. Take it apart and see if there is
noticeable wear on the end plates and scoring on the rotor. Replace if that is
the case.
Always replace the timing chain. The response is always better the first
weekend with a new chain. They will never really wear out or break, but for
$10 you get at least one weekend with that crispness.
Replace the rod and main bearings regardless of how good they look. Use
Vandervell lead/copper. Don't worry about the cam bearings. They always look
awful but seem to be OK that way.
Check/replace any cam followers that show wear or pitting. Check cam for any
abnormal wear. Don't mix the followers up that you are going to reuse.
Do a valve job on the head.
While you are in there, it is also wise to put new baulk rings in the gearbox,
and if you haven't done it already, drill and safety wire the shift fork grub
screws. They will eventually come out at an event if you don't. I guarantee
it.
Make sure the flywheel is on really tight. Use locktite on the bolt. Leave the
locktab off. In fact, the only locktabs that do any good are on the ends of
the gearbox main shaft.
Good luck.
Jack Woehrle
Cooper Car Company
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