318 LA rebuild after losing a valve seat

nm9stheham said

If you have 2.109" + or - measured with 2 good measuring tools, that agree with each other, then it sounds like the crank was turned wrong. .020" undersized bearings will still be an interference fit by at least .003" if this is true.

Check the mic against standards. Dropped mics usually read high, not low. But since your tools agree, I doubt this is the issue. BTW, I'd put the piston in with the .020" under bearings with no rings on it to eliminate the ring drag and leave only the bearing drag. it ought to spin as free as the crank that way.

Where did this crank come from?

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I’ll check again. There’s always the factor of user error to be considered, but the instruments themselves aren’t the issue. I’m confident in that. They’re both practically new and have always been in their cases.

I got the crank from AutoZone. It’s a reman for a 71, this is before I discovered the block is a 73. I remember someone mentioned 71 and 73 cranks are the same, so I put that to bed.

One thing I don’t understand is why it won’t turn when the plasti-gauge said there was .001”. Reading KK’s build tutorial and the service manual, specs are .0005-.002”. If it’s within tolerance, shouldn’t the crank be able to turn?