Can I spin a 14 x 27 cleaver with a 3 cylinder Johnson race motor?

[hoodooguru]

G'day
I race a highly modified 914cc johnson 3 cylinder. High compression head, wiseco pistons, full port job etc.
I ran the boat yesterday with a 13 x 23 (with cupping) srx chopper and did 63mph thru a 2.4:1 ratio gearbox with nosecone.
With a 2.0:1 gearbox roughly what would the speed be?
I also suffered from porpoising. So I plan to move some weight around the boat to test.
But my main question is:
I have a 14 x 27 omc over hub cleaver race propeller I wanna try on the boat. But, do you think I will be able to spin it? I'm thinking I will with the 2.4 ratio box and propshaft 1.5 inches below the pad.
The motopr is VERY healthy (freshly rebuilt). I want to stop the porpoising and get close to 70mph. As the cleaver is a transome lift prop I'm hoping that the porpoising may stop just from a prop change.
Whats everyones ideas?

[hoodooguru]

Pics from yesterday. The seating has just been setback a bit and it runs alot better where it is now compared to when it was forward more. I have the tank and battery directly behind the seat. I plan to put a sand bag in the front to try to see if moving the battery to the front may fix my porpoising issues.246158

[terry taylor]

You left out the important rpm,s

[hoodooguru]

I didn't have time to refit my tach.
I would say I was spinning the srx at around 6100-6200rpm. It was sounding sweet. The prop shaft is approximately 2.5-3.0 inches below the pad currently.

[perfmarine1]

You realy need that tach,without it you are just guessing. With full porting,that is ports raised your powerband may be higher than 6100-6200 more like 6500-6800 the port job depicks the powerband and you need to know. It would be best to find someone with a dyno so you would know where peak HP is. It would save you alot of time proping the motor. Till then just keep trying different props with a good GPS for checking speed.

[donmac]

2.4 ratio /23pitch /63mph --not 6100rpm,closer to 7800? :rolleyes:

[Jason Johnson]

If you are looking for speed, the higher 2.0 or even 1.78 ratios will work much better. Even though you will go down in pitch numbers, 23 down to 21 just to say, You also need to be 1" to 1.5" above the bottom. That will put you rpm up towards 7k. and speed at 70mph plus.
But to answer your question, YES you can, if it is better, you have to go try it to see.