So, in the shake down run of my boat with new (old school HP500 carb) motor, I blew the hexagonal pump to plate gasket. It is the pump that sits in front of the timing cover, not the sea pump. Attempted to install a new Felpro gasket which is thinner than the original, I could tell right away it was too thin and not going to work. It would have locked the pump up as the back plate was riding on the impeller.

Anybody else run into this? Is this a Merc twist on a GM part? I have been unable to locate a thicker gasket, can I stack 2 thinner gaskets?

BTW, I had excessive pressure due to my IMCO lower with large Jenna Jamison sized slot LWP. I already know I need a relief valve.

I posted in the General discussion area with no response

Yes you can stack two gaskets if you can't find a thicker one . Might I suggest that you put a thin skim coat of Ultra Black or Right Stuff between the two gaskets and give it a little time to tack . I would not apply it to the outer sides of the gaskets unless you are very careful when tightening the bolts to prevent squeezing the gaskets out of place . Gaskets get slippery when coated with silicone or RTV .