In a message dated 5/30/05 9:43:24 AM Eastern Daylight Time,
tswrace@pacbell.net writes:
<< To align bore an engine as I understand it the machinist shaves the boss
on the main cap. Then the caps are bolted in place and the mains are
align bored. This results in mains that take standard bearings.
>>
To clarify further. Align bore ( AKA Align Hone ) mains is done to ensure
all bearing saddles are centered so the crank does not rub.
The main caps are cut down a bit it make the bearing saddle smaller, a long
hone bar is then inserted through the main caps and the saddle hole brought
back to size.
For most engines, standard and undersize refers to the inside diameter of the
bearing. ( the side that contacts the crank shaft) but there are exceptions.
Some engines like air cooled VW or Porsche have a crankcase that splits in
two halves rather than main caps. For these motors the saddle hole must be
increased during line hone and a larger _outside_ diameter bearing used. If
the
crank has been reground a smaller _inside_ diameter bearing must be used.
Harold
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