I ran across a guy that has 2 401's, both from boat, 1 is standard, the other is reverse rotation, what all is involved in changing rotation? thanks
On MOST engines just the cam shaft, starter, and water pump. I have not worked on a marine Buick however.
I would check the pistons too. Piston pins are normally offset to reduce piston slap. They would have to be offset the other way, or the pistons put in backwards in a reverse rotation situation. I don't know this for sure but it seems logical.
Pistons are the same. I did a reverse rotation corvair in the past. The distributor gear could be cut the "opposite" way. That way the cam puts thrust on the distributor gear in the correct direction.
"That way the cam puts thrust on the distributor gear in the correct direction." And keeps the firing order right, and prevents the centrifugal advance from becoming centrifugal retard.