De-cipher Piston Markings

[Mark from Indy]

I am not familiar with the history of my motor, or Model A motor replacement parts in particular.

The top of each piston has a 40 stamped in it. Is this a standard after market practice for a .040 overbore piston?

Thanks

Mark

 

[Tom Wesenberg]

Yes, usually it would be stamped .040.
Best to mic the bore to be sure.

 

[colin1928]

That should be 0.040 thou oversize
But just measure your bore to be sure
Colin