B33 pistons

[Platties]

Please can someone explain to me the difference between a short stroke and long stroke B33 piston?
I have a M33 with the B33 short stroke engine from 1954 and would like to fit a +40 new old stock Hepolite piston, but they are an ilusive thing!
Would a long stroke piston not fit a short stroke engine?
If as it sounds, the strokes are different, but the bores are the same. Then the two types of engines must be different cc's ??
Thank you for any help.
If anyone has a piston they would be willing to part with, please get in contact.
Cheers
Andy

[JulianS]

The stroke was the same for all the B33 engines, the later ones had a short con rod. The long rods have casting mark 66 483 and the short rods casting mark 65 1614.

Below is from the 1962 Hepolite catalogue which gives the piston lengths and compression heights. Not the same part for short and long rod engines, whether you can interchange I dont know.

[Platties]

Thank you Julian, that's perfect.

[paulm]

Easy way to tell long rod the gudgeon pin hole almost touches the oil ring short stroke 1/2 inch below not interchangeable, you can convert to long rod using a B31 rod i did due to the shortage of quality short rod pistons at the tome

[Platties]

Thank you great information.
I just got lucky and found a new old stock Hepolite piston, so happy days 😊