I believe a change in mass at the small end will have a greater effect than vice versa as the small end is reciprocating while the big end is rotating . Why not static balance it to original spec ( or at least check it staticky ?We are dealing with solid mounted engine. New rods are heavier than the old ones and I want to know where I will
be if I don't rebalance . How much does it matter which end of the rod is heavier?
You don’t need a lathe to static balance - just a simple pair of parallel and dead level straight edges - the sharper the better to minimize friction.Why not indeed...no lathe...:-(
But I agree about where the weight is.