Remember that you have standard bearings. Make sure that you have the =
correct bearing set for your car and not for something else. Any work =
done to the crank..turning or polishing will make the crank smaller so =
the fit will be looser. The scenario below could only happen if you have =
the crank turned say 20 thousandths (.020") undersize and you got .030" =
oversize bearings. Or if the shop somehow made a mistake and didn't turn =
the crank down as far as they said.=20
A bent crank would have been noticed right away by the shop when they =
started to polish the journals. They should check for straightness =
first. You could have it checked again..or at least ask about it if the =
following stuff doesn't help...
If you still think it's the center mains and that you have the correct =
bearings for the engine and they are the correct size, look very close =
at the center bearing caps..check that they are in the right location =
and facing the right way. The caps did come from this block..right? =
Can't mix'em from block to block without having the block line bored. If =
you can tighten all the caps but one before the crank won't turn, try =
turning that cap around..approach it systematically..you'll find the one =
that's the problem. Check that you didn't damage your bearing shells.
Course dirt under or on the bearing shells is bad. Use a little =
lubricant on the shells and journals..some sort of assembly lube ment =
for this or STP (only thing it's good for). You want something that will =
stay put for a while and that's not motor oil. I used Lubriplate =
assembly lube once..that was bad. looked like it would stay then seemed =
to separate and run. I always used STP before that and ever since. When =
all is right you will be able to turn the crank easily with your hand at =
the flywheel boss at the rear of the crankshaft...you can't spin it but =
it should turn.
If you can't find the problem, don't hesitate to haul the crank, block =
and bearings to your machine shop and ask them to look it over. They can =
see it ..I can't.
You'll find it hang in there!!
Sent: Saturday, August 02, 1997 4:23 PM
To: firstname.lastname@example.org; email@example.com
Subject: Re: Main bearing problem
Back to basics:
Did you mike your crank after it came back from the machine shop?----'Ol =
might have been eating a burger while polishing your crankshaft.
Did you plastiguage the bearings as you installed them? This is vital, =
tells you whether you have sufficient bearing clearance.
This will also give you a clue as to whether you have mismarked bearings =
You might have a bent crank (your shop should have told you this).