No worries - may The Schwartz be with you during the ebuild.

got the bore gauge and outside mic thanks for the location and numbers to confirm.

0.0025" to 0.003" bore clearance.

 

Measure the piston at 90° to the pin around the skirt.

 

You'll need an accurate bore-gauge to measure properly.

I have a 1275 project engine however I am unsure if the parts are all from the same engine or if it was a collection of things that the previous/previous owner never got to assembling. I have a block needing a hone, and pistons, and unknown history. What I am trying to do is determine what the piston to cylinder wall spacing should be because what the Haynes manual says vs. aftermarket guides vs. engine builders on the internet are kind of everywhere. So ill cut to the point; I have a set of AE21253 pistons, .040 over. Where exactly on the skirt should I measure the pistons size, and then what should the cylinder bore generally be over that? Haynes says some large number for stock 1275, but some builders say .002 at the absolute tightest. So what gives? Using the inside and outside mics I have, My block before hone is somewhere around 2.784 at the moment...Might I have a .060 block?