BroncoBilt
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• Seattle, WA, USA |
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• Registered on 11/26/2014 |
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• 16 posts |
• 1 Vehicle
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 Posted:1/15/2015 07:05 |
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I split my cast last night (1996 351W) and thought the crank was shot. turns out, it seems like it was just the bearings that were beat up. I cleaned up the crank and measured it w/ my crppy Harbor Freight micrometer, and even though I might not necessarily get accurate measurements, they were precise. I'm thinking at this point all I need to do is buy some bearings. But I don't exactly know which to get (which undersize) because I doubt my micrometer is off. I might go to a machine shop today and ask them kindly, "please measure this!"
Haynes says: rod journals = 2.3103 - 2.3111"
My readings:
1. 2.312
2. 2.312
3. 2.312
4. 2.312
5. 2.312
6. 2.312
7. 2.314
8. 2.313
Haynes says: main bearings: 2.9994-3.0002
My readings:
1. 2.999
2. 3.000
3. 2.999
4. 3.000
5. 2.999
PS: is it important to get an undersized bearing with a 0.001 undersize? Or just get a set of stock bearings and live w/ the gap? I don't know engine tolerances that well, mainly spent my life working on air-cooled motorcycles. I can't imagine having a gap of 0.001" making that much of a difference, cooling, thrust, or noise wise, but then I'm not a crankshaft rotating around at 3000 RPM throwing a bunch of weight around. Hard to imagine.
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