Re: 4.3 mercruiser roller cam
So you want to gain at a minimum 40+ horsepower on a stock engine? Probably not a good idea. Remember that unlike a car these engines are operated at max load for extended periods of time. This is why the specific power of a marine engine is much lower than most modern car engines.
Stock marine 4.3's went from 175hp to 230hp, he will be fine. The stock higher hp engines had much better heads, roller cam, roller fulcrum rockers, more carburetor and intake. They are tough little engines. Basically a 350 with 2 cylinders cut off.
that jegs engine shows...
Camshaft Specs:
# Lunati Hydraulic Flat Tappet
# Duration @ .050'' Lift: 218 Intake / 218 Exhaust
# Lift: .457'' Intake / .457'' Exhaust
# Lobe separation: 108?
Personally I would use a roller cam. Im also surprised it is making that much hp with that flat tappet.