Street motor dimesions that have been used for 40 years
Main clearances = 0.0020" - 0.0025"
Rod clearances = 0.0025" - 0.0030"
The conservative dimension for the mains helps keep the oil pressure up and encourages oil to flow to the rods. The rod clearance is in line with Clevite's recommendation for a performance motor having 2.31" journal diameter.
By the way ... Grinding a high nodularity iron crankshaft "opens" the graphite nodules located at the surface of the journals leaving microscopic ragged edges which will damage bearings. The crankshaft journals should be polished in the direction of crankshaft rotation to a finish of 10 micro inches Ra. In order for polishing to be most effective it is also essential that the crankshaft is ground in the opposite direction of rotation and/or polishing.
-G
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If you use a 351C 4V powered vehicle for a grocery getter ... the eggs aren't going to make it home!
