Is there a "how to.." for crank measurement, and bearing verification? |
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Is there a "how to.." for crank measurement, and bearing verification? |
malcolm2 |
Dec 16 2019, 11:07 PM
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#1
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Advanced Member Group: Members Posts: 2,747 Joined: 31-May 11 From: Nashville Member No.: 13,139 Region Association: South East States |
I am gonna make a 2 liter from my 1.8. So I have a refreshed 71mm crank that I have been told has been ground to -0.010.
I measured as best as I can with a digital mic and got about 59.66 on the mains and 49.65 on the rod journals. Where can I find the STD specs and ranges ? were they 60 and 50, respectively? Since I know nothing about this crank, how can I verify the 71 mm measurement? |
Superhawk996 |
Dec 17 2019, 02:34 PM
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#2
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914 Guru Group: Members Posts: 6,502 Joined: 25-August 18 From: Woods of N. Idaho Member No.: 22,428 Region Association: Galt's Gulch |
Also for what it’s worth, I provided this crank thinking it was going to a low buck down and dirty rebuild or low buck refresh of some sort.
From your previous posts I think you have invested in new AMC heads and may be building this for a Bus IIRC. I wouldn’t use this crank as-is for for a top notch rebuild. This crank is was polished beyond the 0.010 undersize to remove light scoring. That polish basically equals WEAR. As long as it’s between the tolerances it’s usable but some life was lost and oil clearances would be increased with the polish. Plastigage would tell you where it actually is at. If you don’t want to spend dollars for a standard crank, at least take this one down to 0.020” under, get 0.020” under bearings and start with fresh unworn bearing clearances. Factory manual allows for 0.030” undersize but I personally wouldn’t go that far undersize. |
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