Bearing clearance

[russcc]

Thank you all. Learned a lot. Good points about expansion of the parts due to heat, measuring the mains and rods and grinding the crank to deliver the clearance you want, and oil viscosity vs clearance. The machine shop ended up getting a clearance of 0.002.5, on the mains, which I believe both myself and the engine will be happy with.

[GB SISSON]

This is a very fascinating subject. I think about this kind of thing when I lay awake at night. It's a good point to think of the big end of the rod and it's bearing in a linear fashion. 6" plus of strap heated does get a good bit longer. I argue with a friend who also does a LOT of work on old trucks. In every case he heats stuck bolts cherry red in his (usually successful) attempt to break them loose. I choose to heat the nut or surrounding area if practical. As for bearing clearances, the owner of my local napa store tells me he stocks plastigage for me, as I'm the only person who ever buys it. I'd be lost without it. Thanks all for the info on this thread.

[Kohnke Rebabbitting]

Originally Posted by russcc

Thank you all. Learned a lot. Good points about expansion of the parts due to heat, measuring the mains and rods and grinding the crank to deliver the clearance you want, and oil viscosity vs clearance. The machine shop ended up getting a clearance of 0.002.5, on the mains, which I believe both myself and the engine will be happy with.

Your .002-50 should be correct at that clearance. With oil, you will never hurt those bearings, at break in.

Herm.