i am repowering my boat with a 502 i have a edelbrock 750 carb right out off the box do i have to change the jetting for the 502 thanks mike

You probably do, but I dont know exactly what it would be. Check out sellers who carry the Edelbrock line and look for the jet and rod kit for that carb. BTW- the 750 cfm marine carb is a bit small for your application but should work fine- remember that the common Quadrajet on the 330 hp 454's was a 795 cfm. I have that Edelbrock 750 on my 420 hp 454 and was toying with the idea of putting the Quad back on it.