while polishing a crank i have i noticed a scratch down the center of the last journal were the oil pump hooks. its directly down the center of the crank and looks pretty deep i can hang a finger nail in it. my question is can i polish it back down or should i just chalk it up as a loss . the crank is in great shape with no wear so i was just gonna polish and reuse.

 

You polish to remove raised material so it doesn't scrape the bearing.

If you need to remove a groove, you need to grind the crank down to the next undersize.

If this scratch is right where the bearing groove is, I wouldn't worry about it.

 

ya i would just polish it so that theres no bur's.Lets face it your dumping a tonne of nitrous on it and if ya were you wouldn't be running the stock crank anyway right?

 

yea the scratch is right in the middle were the oil groove is. the only thing is that the oil groove on my bearing is on half the bearing shell the other half doesnt have the groove.

 

shouldnt be a problem, if its not excessive. will just end up being an extra oil 'reservior'. If it was a scratch from end to end rather than around the journal, that would be a problem. just use some emery or scotch bright to soften the edge, and you'll be cool. if it was a broad gouge, make sure it wasn' the oil pump bolt pressing on the bearing shell on the rear main cap, the length of the oil pump bolt is a special length and can get mixed with head bolts,etc.

 

This is what is known in the industry as "an oil retention groove",
Otherwise known as an oops!

 

i've reused a crank or two just as you described with no problems while i had the engine. i use crocus cloth to do my cranks with and use a lathe to hold them, not turn, just hold.

 

Yip cranks with those grooves sell for big bucks hehehe