Topic: Bearing clearance & plastigage question

[Jerry E.]

I have a possibly dumm question about using Plastigage to check crank bearing clearance. Do I have to torque ALL the bolts for the upper and lower cases, to get accurate Plastigage readings? Or, can I just use the 8mm, and 6mm bolts on the bottom case(Crankshaft, and case bolts), since they are the ones holding the crank in place? The other bolts do not seem to do much for torqing the crank down. I bought one set of green bearings, and planned on using them on each journal in turn, to check my clearances( using old bearings to hold crank in place).  My problem is, the two journals I have checked so far, read .006 clearance, which seems like a lot since the old bearings look pretty good, not excessively worn looking. Makes me think I may be screwing something up.

[MRieck]

Just the 8's across the crank will be fine. Greens are good about 95% of the time. .006 indicates the case halves aren't coming together etc. Something isn't right.

[Jerry E.]

Thanks, that what I was thinking, but wasn't sure. I'll check alignment issues with the cases, and measure the length of the alignment dowels. The case/crank codes indicate "green" bearings for this motor.

[Jerry E.]

I found my case problem(rough case alignment pins), and got the crank Plastigaged. I also did the rods(used) I bought to use in this motor. Pretty much all the clearances are in the .00175 range, using the "green" bearings I bought to test. Does that mean I need all "black" bearing shell's, to bring the oil clearances down to the .001 range? Each color down is .0004 I read, so going from "green" to "black" bearings should get me to .001 clearance. Right? Or not?