From: Barry Lovelock
Date: 16 Aug 2002
Time: 07:46:37
Remote Name: 62.6.84.136
Bruce,
Yes, I think the bearings do tighten a bit, but think 4 thou is a bit too much also. General old rule for big ends was 1 thou/inch of diameter I believe. Can't really imagine Austin would have left such a poor fit - smacks of bad engineering. I would have expected no more than 1 thou when new here and whilst it may not matter in reality would still aim for this.
I think all three bearings should be the same and the centre one probably much tighter - this is the one where loads of wear takes place - remember people turning the race around to take out the thrust wear!!
To some extent, the end ones will be compensated by oil film, but the centre one can't. I feel such looseness will be reflected in increased timing gear knocking - already a problem area in A7 engines. I totally disregard any matching numbers in this area now and actually mix and match to gain minimum safe running clearance which, importantly, gives minimum knock too.
Barry.