Sorry having no motor model number but it is a mid 80's 470/170.motor blew last summer and i have a completely remanned long block installed back in. After a couple issues it runs fine but I cannot get anymore than 4000 rpm's. Anymore throttle past 3/4 it gets louder and i got that boggy sound but very little power and speed out of it. She performs great right till that 2/3 - 3/4 throttle. I also get alittle sputter pushing it too full throttle but i got that with the old motor too. With all the performance upgrades this engine should get me at least 4300 rpm's and 34 mph but all i get is 4000 and 26 mph Here's a list of what is new and what I have tried with no luck. New fuel pump, new flame thrower coil, new electronic ignition, new plugs, wires, and D cap (2017) rebuilt carb, new slave starter solenoid. Have tried playing with the timing and have alittle success advancing it to 8 degrees, i have tried turning out the carb jet screw to allow more fuel in,. I have not tried retarding the timing, i have not checked the fuel filter as it is a rebuilt carb. I've read a similar thread about this and theres all kinds of theories. One odd thing is when i try to punch it to WOT my tach jumps around some. It sure sounds like a fuel issue to me as I get that bogging sound, starving for fuel as the carb opens up. Sure sounds like it would be something simple but... its a boat! I appreciate any help!
