Same scale (new) same day

8-28-72 340 4.070 158#
2-19-71 318 4.070 122# was a running dirt track motor
5-7-70 340 4.070 159#
10-17-96360 4.040 175#
6-17-70 360 4.030 165# smallest distance between farthest apart bores
4-26-78 360 4.030 165#
1-2-97 360 4.000 179#
7-19-91 360 4.000 174# Roller has the thick pan rail also
8-30-73 318 3.910 165# Same casting as 122# block
9-19-96 318 3.910 177# Has thick pan rails
1-16-67 273 3.625 166#

I got all these blocks in my shop right now, weighed them tonight on new digital bathroom scale. They have freeze plugs, cam bearings, main caps and main bolts. If they did not have them for the weigh in I set a spare set on the block while on the scale.

All the magnum blocks have the thicker pan rails weather 318 or 360.

The space between the bores was measured with a flat screw driver through the freeze plug holes, not real scientific but it is what I had. The 340 blocks were both the tightest ones by far except the two center cylinders on them had more space than the tightest one on the early 360 block. The 273 was the worst.