line boreing for insert main bearings

[steamgas]

what is the diameter the block needs too be line bored out to too except insert main bearings?please give machinist numbers and tolerances.this is an early Babbitt block that i want to update to insert main bearings.

[hotrodA]

The dimension is a spec from the bearing manufacturer for the bearing's crush fit. If your machinist is capable of line boring and honing, he should have the spec.

[deuce_roadster]

I think I would only trust my block with a machine shop that has done this operation many times over someone who has never done one.

[rotorwrench]

If it's the old 2-inch babbitt type mains then someone has made shells for those but the main bores not only have to be set up for the replacement shell diameter but they have to have the locking reliefs cut too. I would leave this work to someone who has been doing this in the past. There aren't too many folks out there doing this. There are more guys still pouring babbitt than there are guys machining for insert type bearings.

[jimTN]

There is also a different distance between the main bolts, babbit mains have the bolts closer together.

[jimTN]

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The bolts are closer together on babbit blocks also.

[David J]

Big issues here and all 3 are like this .

[Lawrie]

David,find some who can re babbit them,in my old babbit 33 engine,after rebabbiting it was as smooth as ,and as fast as the 99a engine in it now,not as much torque but a realy nice engine,and it will do lots of miles,moRe if you filter the oil.
There are good guys still doing the rebabbiting.
Lawrie

[Ol' Ron]

Considering the cost of rebuilding these engines, running with out a 95% oil filtering system is foolish. Especially considering the fact that the system cost less than 50 bucks including remote filter. I place mine under the car on the frame behind the steering box, so it;s very hard to see.