Re: Best way to break in a rebiult motor

Posted by RN on November 27, 2004 at 19:51:05 from (166.126.218.219):

In Reply to: Re: Best way to break in a rebiult motor posted by JD790 on November 27, 2004 at 19:14:10:

Bearing to journal fit on not machined cranks- Old machinist I worked with did many bearing jobs on lightly worn cranks- concern was for faint grooves and slight egg shapes or pits on crank journals. Bearings were selected +.003 to .005 undersize soft coats Clevites or special size from TRW catalog. Clearance installed was close to minimal factory specifications. Bearing top coat usually matched to journal in few hours- if crankbearing wore offside could note oil pressure low. This was very rare but thrust bearings did have a couple problems- Crank journal thrustface wear grooved or a bit excess. Watch oil pressure, listen for rod knocks. If crank was worn more than undersize +std or more than .003 variance over factory spec after measuring 8 points on crank journal or rolling dial indicator gauge around journal- crank grinding time to -.010. Ford truck 351s, 302s can wear rod and mains under load, Ford factory has service bearings undersize from .002 to .006. Thought in service bay was partial external balanced cranks vibrated a bit and had greater wear than GM cranks. RN.

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• Re: Best way to break in a rebiult motor JD790 21:27:26 11/27/04 (0)

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