The grooves were placed in the pistons for two reasons:
(1) To reduce friction because of less area contact of the piston to the cylinder
(2) To make it more difficult for restorers to reproduce the pistons
The use of an O-ring would negate number 1 above.
Jerry said it well.
And Jon G, I really do think it admirable of your research. Much is learned by persistant (a.k.a. stubborn
) individuals that continue to research where others have ceased to do so.
And since we are for the most part talking about truck applications; one can always improve the Rochester B by hiring a 15-year-old to stand on the running board (trucks!) and pour fuel into the engine from a leaky boot!
Jon.
