Alan,
The allowable specs for a standard U20 crankshaft are:
Main Journal diameter: 2.4780 - 2.4785 in.
(can be ground to 0.010, 0.020, 0.030, and 0.040" undersize with same
tolerance range as standard).
Main Journal taper & out-of-round: less than 0.0002 in.
Main Journal clearance: 0.0008 - 0.0028 in. (wear limit 0.0047")
Rod Journal diameter: 2.0449 -2.0454 in.
(same undersize steps as Main bearings)
Rod Journal taper & out-of-round: less than 0.0002 in.
Rod Journal clearance: 0.0013 - 0.0034 in (no wear limit specified)
Rod big-end free end play: 0.008 - 0.012 in.
Crankshaft free end play: 0.002 - 0.007 in. (wear limit 0.012")
Max crankshaft bend: 0.0012 in.
BTW, all these specs are in the Factory Service Manual (available from
most venders) and the "new" Repair and Service Manual (available from
Fairlady). I highly recommend you get one or both of these repair
manuals if you're this deep in to repairs.
Todd Osborn
68 2L DATSFUN
San Jose, CA
Alan Horton wrote:
>
> Hello All,
>
> I would like to know the acceptable measurement range of the journals (main
> and rod) for the U20 crank. Also, I think that my crank may have wear at the
> rod journals, what bearing size increments are available to compensate? Any
> help would be appreciated.
>
> Thanks,
> Alan Horton
> Spartanburg, SC
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