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Difference between main bearings?
Posted: August 12th, 2015, 4:21 pm
by nicpaige
Does anyone know the difference between the Clevite main bearings part # MS704P and MS1947P ? I have a 1985 12wt 4.2 crank and a 1999 4.0 HO block. Which main bearing set is the correct one? Thanks
Re: Difference between main bearings?
Posted: August 12th, 2015, 4:38 pm
by SilverXJ
The MS704P is for the 258 and 87-90(renix) engines
The MS1947P is for the 91+ 4.0L
Re: Difference between main bearings?
Posted: August 12th, 2015, 5:44 pm
by nicpaige
So for a 4.2 crank in a 4.0 block are you buying main bearings for the crank or the block? Or maybe it would be simpler to just ask which would be appropriate for my combo listed above?
Thanks again. Im in the home stretch. Final hone and Im ready to assemble.
Re: Difference between main bearings?
Posted: August 12th, 2015, 7:37 pm
by jsawduste
Block
Re: Difference between main bearings?
Posted: August 12th, 2015, 9:00 pm
by IH 392
Yes the main bearings MUST be for the BLOCK, NOT the crank.
Re: Difference between main bearings?
Posted: August 13th, 2015, 6:16 am
by Cheromaniac
All of the above posts are correct. You'll need the MS1947P main bearings for a '99 4.0 block as those have central locating tangs. The earlier MS704P main bearings have offset locating tangs and won't fit in '91+ HO blocks.
However, rod bearings and ARP rod bolts are interchangeable between 258 and 4.0 engines of all years as the 258 and 4.0 rods share the same big end dimensions.