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Prop Pitch
- Thread starter Senator
- Start date
What speed and rpm are you getting out of the current prop?
1975 Checkmate Tri-mate 2, 2.4 200+ / Sky jacker 6" plate / 25p Laser 2 prop
1975 Checkmate Tri-mate 2, 2.4 200+ / Sky jacker 6" plate / 25p Laser 2 prop
The original speedo reads somewhere between 50 and 60 mph, at 4200 rpm. Last night I pulled the spark plugs, and they were snow white. We replaced the spark plugs, put larger jets in the carb, and replaced all the carb gaskets. The
timing has been readjusted. As far as I can tell the motor is bone stock, I was curious what the boat originally came with. Every one tells me that the prop is too big.
timing has been readjusted. As far as I can tell the motor is bone stock, I was curious what the boat originally came with. Every one tells me that the prop is too big.
Eriktheviking
Member
A typical prop for your boat would USUALLY be a 14 1/4 x 21 or 14 1/4 X 22. Judging buy your low RPM's I'd suggest trying a 19 Laser II prop. You need to measure the diameter of your current prop and let us know. What brand is it? Your Top speed RPM's should be around 4800 at 58-60 mph. The Senator is a great boat, you just gotta get yours dailed in!
The prop on the boat is called a Vengeance by Mercury Marine. The diameter is 15". Top speed is about 58 mph @ 4200 rpm. The motor seems to have great mid range power, but seems to bog a little when trying to get on plane. Any advice on carburetor settings? I am currently running 71 jets, and the plugs are still a little light. The timing is set between 10 and 11 degrees.
Eriktheviking
Member
You should try out a couple props if possible.I think you'll find a smaller diameter prop like a Merc. Laser II or TURBO would really wake that boat up.I believe your engine is bogging because it doesn't have the torque to turn that 15" prop.I had an 87 Senator that did the same thing. Those RPM's need to be up to 4800 wide open. A cheap upgrade for your engine(performance wise) would be an Eldebrock Performer intake manifold.They're only about $100.00. They were installed by Merc. on all their 270 hp 350 Magnum engines.