273 block measurements are done. '68 273, never rebuilt.
One thing I realized is that, as long as the dial indicator and its base are stable on the crank flange, then any crank flange runout does not matter. As long as all is stable, then the dial indicator body is going to move in a level circle perfectly perpendicular to the axis of rotation. So this is why the OP saw no difference regardless of the orientation of the dial indicator base on the flange.
FWIW, this particular crank flange has a total of .0015" runout. I found the + and - spots and put the dial indicator arm 90 degrees to that before I realized the above. I had to use a length of thick metal (an old heavy duty extension shackle) bolted rigidly to the crank flange to extend the dial indicator short arm far enough.
Working in a CW direction around the bell flange of the block, and looking from the back, with a + indication being towards the trannie:
Left dowel +.001
10 o'clock hole +.002
11 o'clock hole -.002
12 o'clock hole .000" (Reference)
1 o'clock hole +.000"
2 o'clock hole +.003"
Right dowel +.004
There were +/- .001-.002 " variations around the holes and in various spots. The dial indicator is marked in .001" increments so is nothing super special.
Looks like this was not a Monday block....and Treblig wins a prize! LOL But, this does not prove that all blocks were this good or that the OP's could not have been so far off from the factory. All we know is that it is now.
FWIW, the decks on this block have been measured on this block using the new 4" stroker crank and a single piston & rod assembly. You can see that the crank bore is generally straight with the decks, except for the big drop off at the back on the left bank.
View attachment 1715270016
