Size (height) matters

[brighton911]

I was assembling my engine this week and ran into a slight snag. Background, I had bought a set of 3.4 P&C from the forum. Low miles, both pistons and cylinders looked great, second ring wasn't even fully broken in. The cylinders were were numbered 1 to 6 and I did measure the heights and 1-3 and 4-6 were in the same height group. When I disassembled my engine, I had taken the heads and cam carriers off as a unit. They were wonderfully leak free so I didn't want to mess with that. Upon reassembly, once torqued down to 11 lbs, I found the cam on the left side was binding, just a little but still not acceptable. So off with the heads to investigate. Using hold downs on all the cylinders, I put my straight edge across all 3. On number two, there was a gap of 2-3 thou on the side adjacent to #1 and less than 2 on the other side of #2. It appeared #1 was a little high so off with it.
My low tech surface plate is a piece of 1/2" glass with 3M 120 paper glued to the glass using spray adhesive. I have used it to flatten valve covers, cam chain covers etc with good success. Using it, I took probably 2 thou or less off the top of #1, cleaned it up and reassembled, minus the piston in case I had to remove more material. Torqued it up and bingo, no binding! Amazing how so little difference in height caused the binding. Too bad I didn't check all the base gaskets for thickness differences, perhaps number one was a little thicker than the others.