64 383 Piston markings question

[Bob Wright]

I traded my 49 Plymouth Super Deluxe a couple weeks ago for a clapped out 64 Polara. I have removed the engine and pulled apart the engine.

I have a question about markings on my pistons.

Near the wrist pin (at about 3 or 4 o'clock position) on the side facing the rear of the motor 4 of the pistons (1,3,4,7) have a 10 cast in them, the others have some symbols cast that I do not believe to be numbers. See attached picture ... piston on left has the 10.

Is there any significance of the 10? Does it indicate 0.010" oversize - if so then why are only 4 marked.

I have measure the bores at about 4.250 to 4.256" - so I don't believe they are bored oversize (but neither do I 100% trust my measurement technique.

Thanks for your advice ... and I appologize if this has been discussed before ... I didn't find it when I searched.

 

[miller]

Might be just a mixed set of same size pistons. Heh, they did that sort of thing back then. And, back in the day, most oversize stamps were on top of the piston.

Your bore measurements can be pretty accurate, with only .006 difference. Block should clean up nicely!