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Need help with Alpha One gear/prop setup

P

ProSA

Member
Need help with Alpha One "Gen II" gear/prop setup. I have a new 350 motor installed with approx 330hp, running around 5000 rpm WOT with a 23P prop, top speed around 55mph. The old motor was a 5.0L. My understanding is that the stock gear set is different for the 5.0 than what would be used for the 5.7 motor, therefore I'm thinking I have the "wrong" gearing in my Alpha.

Questions;
Will changing the gears create more top end speed?
Will changing the gears be better for the outdrive?
I assume I will need to change the prop?
After changing the gears/prop wouldn't I end up at the same WOT/speed???

Any & all advise would be helpful,
Steve
 
I would definitely play around with prop options before I started messing around with the gearing. One lonely prop nut vs tearing apart the out drive... I would try a 25" mirage plus on there & see how the boat & rpms handle it. Jmho...
 
Yes I would also just play with prop selection. As far as I recall the alpha uses a v-8 drive, v-6 (1.65)and a 4 banger (1.84?) drive. Don't think I have seen a different setup for a 5.0 vs 5.7 (1.50 or 1.47) also some cruiser alphas had 1.36 I believe. I would want as close to 1.50 as possible. I'm sure there are even some BBC alphas living on the edge out there. My 2 cents.
 
Last edited:
Hack said:
My brother's Baja Sport 210, 454, Alpha 1 outdrive. Bought new. Still alive and well.

Sorry for the hijack...
Click to expand...

haha no highjack . We are talking about alphas here lol. They are pretty strong and I have been told 300 hp and heard up to 400. I guess it depends on maint. ,abuse and a little luck never hurt any.
 
Problem Child said:
They are pretty strong and I have been told 300 hp and heard up to 400. I guess it depends on maint. ,abuse and a little luck never hurt any.
Click to expand...
Yup. Probably heavy on the luck. I think his was the last year for the Alpha drive BBC. I think his was new in 1985 or 1986. So 30 years or so behind the 330 hp BBC.

From what I've read, I agree that 300 hp is the recommended limit on the Alpha 1. Like most drives, too much torque on the wrong prop, and too heavy a hand will hasten their demise.
 
ProSA said:
Need help with Alpha One "Gen II" gear/prop setup. I have a new 350 motor installed with approx 330hp, running around 5000 rpm WOT with a 23P prop, top speed around 55mph. The old motor was a 5.0L. My understanding is that the stock gear set is different for the 5.0 than what would be used for the 5.7 motor, therefore I'm thinking I have the "wrong" gearing in my Alpha.

Questions;
Will changing the gears create more top end speed?
Will changing the gears be better for the outdrive?
I assume I will need to change the prop?
After changing the gears/prop wouldn't I end up at the same WOT/speed???

Any & all advise would be helpful,
Steve
Click to expand...

Something sounds hinkey. if you google prop slip calculator and add in your info the boat should run mid to high 60's. the gen 2 alpha one with a 5.0 should have the same ratio (1.47) as a 350. Either the info you supplied is incorrect or your out drive ratio was changed before you bought it.

Assuming you are trimming the boat out correctly then the gear ratio that fits those numbers would be 1.81. This would give more torque but less top end. I would either check the out drive to see if it is listed or pop the top cover and count the teeth. A 1.47 should have 20/22 teeth and a 1.81 should have 17/19
 
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