In <Pine.SUN.3.91.950920140701.6913D-100000@northpole.med.uvm.edu>, W. Ray
Gibbons wrote:
>Which brings to mind a car question. If you have the main bearing caps
>line bored (should that be "align bored"?) as Denise suggests, does that
>enlarge the bearing holes? What do you do then? Are bearings made for
>oversize caps?
>
Line boring (well, gosh, Uncle Ray, that's what the Old Farts at the
machine shop call it) was a necessity for engines with poured babbitt
bearings. With the advent of shell bearings, the necessity for this
difficult and costly practice was eased substantially. In theory,
once the block is line bored at the factory, replacement of shells
should keep the mains in alignment. The big however is that one must
always replace bearing caps in the correct slot (and the right way
'round). This is currently a problem for the chappie who has
apparently mixed up some of his main caps over the years. One usually
can find with careful inspection some marker (like punch pricks) on
the caps to indicate to which journal they belong and well as the
proper installation orientation. I cannot imagine a necessity to do
line boring on the mains unless a bearing has spun, and I have never
seen caps with oversize OD's, though such creatures may exist.
A. B. "Boring is my middle name" Bonds
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