I want to have my crank machined but I would like to know how much and from where. I was a moron when I installed the pistons and dinged the rod journals and the mains aren'tall the same size. How much should I have taken off each one??? I was thinking .010 offthe Rod journal and .003 from the mains. What do you think??

thanks,
lars

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'92 RS 305 TBI
K&N Open Element
Ultimate TBI mod's (thanks Pablo)
Cam[.442"/.465"] x 218*/224* @ .050", 10:1 Hypereutectic Pistons
Performer Manifold
Shift Kit, Corvette servo,
and 2800 Stall Trans Specialties Converter,
Gutted Cat, IAT Resistor
MSD Blaster Coil, Accel Cap and Rotor

 

take it to a machine shop and let then decide. you only want to remove what you have to, nothing more.

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ICON Motorsports
1st & 3rd

 

Depending on how bad the nicks are they can be filed off without machining. Typically cranks are ground undersize in .010, .020, or .030" on any of the journals and that is the sizes of us bearings you can get. Talk to a machinist about your requirements.

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82 z28 350cid, vortec heads, comp 262h cam, Holley 600cfm carb, 2in twice pipes, MSD ignition, turbo 350 trans, 3.73 posi, manly b&m megashifter

 

That's kinda what I figured. Guess I'll have to wait till I get it out and see.
Thanks,
Lars

 

The "conventional" way to fix a rod-bolt dinged journal is to wrap it with fine emery cloth, wrap a flat string like a shoe string around it a couple of times, and pull back and forth on the ends to LIGHTLY sand off the ding. Then, thoroughly clean the surface and oil holes, plastigage the results, and go (if the plastigage comes out okay).

You'd have to have mashed it pretty soundly to require it to be turned. You didn't indicate if this was a re-ring type job (crank hasn't been turned) or a rebuild (crank was turned), but if you do end up getting it turned, do like ede said and let the machine shop decide how much. Then, buy your bearings accordingly - there's no problem having rods and mains at different undersizes, but since bearings come in sets, all the rods should be the same size as the other rods and all the mains the same size as the other mains.

Edit P.S.: Having a well-radiused "divit" in the journal isn't a killer. Remember how the oil gets to the bearing?

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82 Berlinetta, orig V-6 car, now w/86 LG4/TH700R. 2.73 unlimited slip. Cat-back from '91 GTA, Accel HEI SuperCoil. AMSOIL syn lubes bumper-to-bumper. Daily driver, work-in-progress (LB9 w/ZZ3 cam, TBD heads, exhaust, paint, etc.).
57 Bel Air, my 1st car. 0.030 over 396, Weiand Action+, Edelbrock 1901 Q-Jet, Jacobs Omnipack, 1-3/4" headers, TH400 w/TCI Sat Night Special conv & shift kit, 3.08 10-bolt, AMSOIL syn lubes bumper-to-bumper. Best 15.1 @ 5800' Bandimere. Daily driver while Camaro was being put together.

[This message has been edited by five7kid (edited January 10, 2001).]