340 Block Bored to 4.160????? Help

Agreed.

I think the poster above questioning the measuring tool is in to something. I'm a 3D drafting engineer, I've seen even good brand micrometers, especially digital ones be off by as much as .25 of an inch. Especially if they've ever been dropped. We have ours calibrated every month and replaced twice a year for that every reason. But that's because we require a tolerance so tight, most machine shops can't do the work. We get down to .0000008 tolerance. Standard micrometers are certified normally to .0001 or the cheap ones even less
I am thinking snap bore gauges and a micrometer would be the best way, then you could also measure taper or top and bottom measurements. If someone is opening vernier calipers across the top of the cylinder, it may not be real accurate.