cranksheft question

[kudzu3 323]

I'm in the process of rebuilding a Kohler 301 (12hp) and have almost no experience, so please forgive my ignorance. The machinist confirmed that the bore is going to have to go .20 over, no problem. My confusion is in the crank journal. The specs I have are probably very clear to most, but I'm having some problem understanding what I need to do, if anything. First. NAPA measured the journal at 1.5, the specs say standard is 1.5015 and .010 is 1.4915. This is confusing to me, simply because of my ignorance of the subject. First, is the crank at 1.5 worn enough to need turning? Second, if I go with a standard size rod here, will I be okay? Third, should I trust NAPA with that measurement? I know I should have taken the crank to the machinist, but didn't and he is about sixty miles away and I hate to drive that distance just for a measurement. I need this info so I can order parts, Thanks.

[oldredrider 2,547]

Unfortunately, your machinist should be the one measuring the crank. NAPA SHOULD have given you a more accurate measurement...carried out at least 3 digits like 1.495. 
From an accurate measurement, the machinist can determine whether the crank needs work or not and if you need an oversize rod.
You're not the first person to find out the hard way. I was.

[rmaynard 14,898]

The crank pin, which is the part they measure, can be out of round. A simple measurement of just one spot on the pin can give you a false reading. The crank pin needs to be measured in at least two spots. The spot where the rod is sitting when the plug fires is going to tend to flatten out, giving you an undersize reading. If the measurement is taken at a spot 90° away from that spot, you may get a reading that is normal, making it look like there is no wear. So as Paul said, you should have the crank measured by the machinist that is going to do the work. He will know how to read it correctly, and grind it accordingly. Let him tell you what size rod you need.

[kudzu3 323]

Thanks folks. That was my thinking also, but because of my lack of experience, I needed confirmation.

[can whlvr 991]

don't forget that the machinist will tell you what to order and before they machine you give them the parts

[953 nut 51,721]

If you have a new standard connecting rod available to you you could buy some "Plastigauge" to check the assembled clearance of the rod on the crank torqued to 22 ft/lb. The clearance should be at least 0.001" and not more than 0.002" as. This should be checked at the top of the crank's travel and on one side.