Bearing clearances

[Clem Z.]

cast cranks must be polished in

direction of rotation because it raises the platets and it will tear up the bearing inserts if polished in the wrong direction

[Michael H.]

Re: cast cranks must be polished in

Yup. Bet there are some engine builders that don't know this.

[Clem Z.]

Re: cast cranks must be polished in

it happened to me years ago and when i talked to bill howell about it he set me straight on the polishing

[Michael H.]

Re: cast cranks must be polished in

I don't think it's as much of an issue with standard main/rod bearings but it certainly was with with the hard M400/M420 or Clevite 77's.

[Clem Z.]

i was not aware of that but i always had

the crank polished in the correct direction

[Scott Marzahl]

Re: cast cranks must be polished in

Well now I learn this. Advise please, I just hand polished a 350 cast crank per the instructions in the Chevy Power Manual using 400 wet and dry with oil and a large diameter string. Of course the engine is assembled on the stand with Clevite 77 bearings..go figure. Should I pop off the rod ends and carefully repolish it the direction of rotation to ensure that there isn't any raised grain to chew up those bearings?

Scott

[Michael H.]

Re: cast cranks must be polished in

Scott,

You should be ok with your polish operation because you did so manually. For every pull in one direction, there would have been one in the opposite direction to cancel the previous so no absolute directional pattern would occur.

The problem occurs when polishing in a fixture with a emery strip.

[Scott Marzahl]

Re: cast cranks must be polished in

Thanks for the sanity check Michael.