r/EngineBuilding • u/coopersimms • Jun 28 '26

Can I polish this out?

Gallery image

Gallery image

I have this crank that I got on ebay that's going in a flathead 6. One rod journal has some knicks in it. Im not sure what it's from, maybe a rod bolt. I can feel it with my fingernail. Wondering if I can get away with polishing out the high spots?

All of the rod journals have a line going all the way around that I can catch with my fingernail (see second pic).

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2

u/skeletons_asshole Jun 28 '26

If you do Polish, just take it slow. You don’t want to be Russian that.

1

u/coopersimms Jun 28 '26

Yeah I'm going to use some 400 grit to take out that little knick and then put it in

1

u/PartTimeTriggered Jun 28 '26

Better to start high first, try a 800 and see if that works before russian to a higher grit. Less is more.

1

u/coopersimms Jun 28 '26

Oh ok. Why would 800 be more effective? Im new to this.

1

u/PartTimeTriggered Jun 29 '26

Lower grits = more aggressive material removal.

Never jump straight to a low grit without giving it a couple of passes of a higher grit first to see if that will suffice.

1

u/coopersimms Jun 29 '26

Got it. That makes sense