1987 Carver Mariner 36'. In 2008 the engine were replaced with rebuilt twin Detroit's 4-53 140 hp,rebuilt trans and V-drives. New shafts, cutlass bearings and genny. The old owner lost interest and sold it to a guy who know nothing about boats he screwed up a lot of stuff. He only put on 400hrs on the boat moving at 10 mph. The props were way out of pich. There now set as 4 blade 22" X 25 pitch with a med cup. I have spent the last year putting the boat in working order.

My questions is the rebuilt Detroit's are a lot heaver the the gas engines and it sets very heavy to the Stearn. The bow sets pretty high from what it should be. I am guessing about about a 12 to 15" to where the water line should be. When I try to get the boat up on plane the tabs are all the way on for bow down and the bow just keeps on rising and the Stearn just digs a hole.
I am pretty sure I need to add ballast to the bow but I don't know how much to add and do I need to increase the size of the trim tabs?
I am hoping that some of you old salts can help me with this issue.
Thanks
Dave
Palm Coast Fl.