Very loaded question.

It boils down to depending on oil temperature, oil weight, journal size, rpm, hp. Among others.

Jmo

GT

Or should I send the crank in to have .002 ground off to make the clearance at .003


Sent from my iPhone using SoCal Jet Boats

Brown & sharpe o.d. Mics and a fowler bore gun with a calibrated ring gage!


Sent from my iPhone using SoCal Jet Boats

Are you finding that the crankshaft journals are oversized or the bearings undersized?  Is this on both the rods and mains?  If the crankshaft is within tolerance, have you checked the line hone in the block and bores in the rods (measured perpendicular to the parting line)?

Just curious, did you qualify your OD micrometer to your bore gauge?

Not doubting your skills or technique, just trying to help you find the source of the problem.

I'm not sure what to do,

1. Have the crank polished to allow .003-.004 clearance

2. Find someone that make undersized bearings?

3. Just leave it, and run it!

** if I was to run it with these tolerances would I have problems running melling hv oil pump? Or would I have to run a std pump!

Thanks flusher for helping me out


Sent from my iPhone using SoCal Jet Boats

The mains are .0025 except #5 it is .003. As far as calibrating the od mic, I used a calibrated ceramic gage block set. I just had the block line honed and and the crank is new from scat, it came as a stroker kit

What are the actuals on the crankshaft?  I will look up the factory blueprint specs when I get home unless someone knows them off hand.

I really don't trust production tolerances.  I measure everything!

I'm not sure what to do,

1. Have the crank polished to allow .003-.004 clearance

2. Find someone that make undersized bearings?

3. Just leave it, and run it!

** if I was to run it with these tolerances would I have problems running melling hv oil pump? Or would I have to run a std pump!

Thanks flusher for helping me out

1.  I'm not a fan of taking that much off by polishing, it will make the journals out of round.  Polishing is really a micro-deburring process intended to remove the microscopic burrs left by the grinding process.

2.  Check the crankshaft to blueprint specs and proceed from there.

3.  I would definitely not run a HV oil pump.  Please consider a factory L-88 pump.  In most engines, with reasonable clearances, the oil pumps operate in bypass all the time, which unnecessarily heats the oil, not to mention the stress on the distributor gear.  Yes, I too used to subscribe to "more's law," if some's good, more's better.  Been there, done that, bought the T-shirt, and I have a really expensive pile of busted up junk to show for it.

Always happy to help brotherman.  I hope something positive comes from it.

Cheers,

Joe

What if my bearing clearance is .002 - .0025? Can I still run the motor with a lower wt oil? Or will I have catastrophic bearing failure?

Which bearings? Your rod bearings?

Based on what I can gather through this thread, if:

• Your rod bearings are  .0020" - .0025"
  
• Your main bearings are .0025" (except #5 is .0030")
  
• Your engine is "5k rpm just a cruiser, not a race motor"
  

Then you're ball parked just fine for your application.