Good afternoon, I've been digging for crankshaft tolerance specs for the mains and for rods for quite some time now. I figured I join this forum in hopes of finding some information about it. I found some clearance specs for a 1968 model 225 /6, which were .0002 - .0022 specified and .0005 - .0015 desired. My engine I am rebuilding is a 225 out of a 1973 d100 half ton truck. As far as I know they should be the same specs but I'd rather be safe than sorry and see if anyone could provide me with actual specs for that period. According to the engines stamped number, it is in fact a 1973 engine and the stamp date is April, 19th. it is also a BH engine if any of that helps. So if anyone knows the bearing clearance specs for the main bearings and rod bearings be sure to send them my way! Thanks! -Bryce

I always set mine on the loose side. For a non-racing application, I recommend 0.0015 on mains and rods. I usually go 0.0020" for racing on that vintage engine.

Happy building,

Lou

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.0005" would be very tight. Probably wouldn't get good oil flow if you used a 20W oil, especially until fully warmed up.