[Dominic]

I recently installed a nicely built 350 chevy into my 1984 Bayliner 18ft boat with a Volvo Penta 280 outdrive and i ran into a wierd problem. Boat pulls great up to 4000rpm, as soon as i open the secondaries and go full throttle it revs instantly to the rev limiter (5800) and the boat slows down. Next i tried to roll slowly into the throttle and it did the same thing, seems as if the prop just spins in the water without pushing the boat anytime i go full throttle. If i hold it at 4000rpm the problem is not there, already going 45mph at 4000rpm, and if i roll into the throttle it still does it. Seems like the boat looses speed and it comes off plane and the rear sinks down when this happens.

Am i cavatating the prop? wrong pitch? I'm lost and i'm so new to boats i have absolutely no idea where to start. Boat hauls ass, is very snappy, and runs great, all the way up to the point i go full throttle. Engine will make a HONEST 375 to 400 hp. Am i overpowering the outdrive? Or is this more of a propeller issue? If it is a prop issue how do i pick the correct one?


Any help would be very much appreciated!

 

["Flat" foot'n]

What pitch prop and is it aluminum or stainless? If you hammer down from a dead stop, does it slip or go?

 

[TNYoungblood]

Sounds like you have some outdrive issues goin on

 

[Gfinch]

I bet you spun the rubber hub in the prop. Take to a prop shop have a new hub installed.

 

[Dominic]

I have been told by many people not to go full throttle at less than 15/20mph so i have never tried to do that. I was also told by a friend i might of spun the hub in the prop, or maybe a clutch tower problem? How can i diagnose the problem so i can pinpoint it and fix it?

 

[Dominic]

Forgot to add, it's a 3 blade aluminum prop not sure of the pitch, the numbers are not readable. The person i purchased the boat from just had a new prop installed before i bought it. The prop was never used untill i bought the boat.

 

[Gfinch]

I have been told by many people not to go full throttle at less than 15/20mph so i have never tried to do that. I was also told by a friend i might of spun the hub in the prop, or maybe a clutch tower problem? How can i diagnose the problem so i can pinpoint it and fix it?

Borrow a prop.

 

["Flat" foot'n]

I have been told by many people not to go full throttle at less than 15/20mph so i have never tried to do that. I was also told by a friend i might of spun the hub in the prop, or maybe a clutch tower problem? How can i diagnose the problem so i can pinpoint it and fix it?

Borrow a prop.

X2
3 blade aluminum is pretty weak with that power. Probably need a 3-4 blade stainless 24 pitch.

 

[[email protected]]

X2
3 blade aluminum is pretty weak with that power. Probably need a 3-4 blade stainless 24 pitch.

would try a prop the clutch will hold at high rpms it would be more of a problem at low speed pull the prop you can see if it was slipping there will be grooves where it rides on the thrust washers

 

[Dominic]

Thank's for all the info!! I will pull the prop and check the hub and washers. I was also concerned about the clutch tower, but it does not feel like the clutches are slipping and like i said it never gets power put to it untill im already moving a decent speed. What's the difference between stainless and aluminum props? and what's the difference between 3 and 4 blades?

 

[BDMarine]

I'm not 100% sure about the volvo, but typically you can put the drive in gear, grab the prop and try to turn it. If the hub is bad, you will be able to turn it and the propshaft will not turn.

 

[f_inscreenname]

Mark the hub with a line and then go run it. See if the lines still match up.
Volvo drives are tough as nails and never saw one that would do what you say it does. They work or they are broken.

 

[Dominic]

OK, found a huge problem,

The hub in the prop is slipping, and it's all torn up. Time to buy a new prop and hub. What would you all reccomend? Stainless? Aluminum?

 

[f_inscreenname]

OK, found a huge problem,

The hub in the prop is slipping, and it's all torn up. Time to buy a new prop and hub. What would you all reccomend? Stainless? Aluminum?

Stainless Solas. Solas is about the only company making props for Volvo Penta anymore.

 

[neil450]

i say try a 22p 4 blade stainless for starters seems like an all around good pitch ever one uses

 

[f_inscreenname]

i say try a 22p 4 blade stainless for starters seems like an all around good pitch ever one uses

Way to much for a 350 IMHO. I would start with a Solas SS 3 blade 19P

 

[bkaltec]

Glad to see another hot rod bayliner.

FYI Cavitation is like boiling water, ventilation is air around the prop causing slip.
My prop cavitates as seen here.


If your boat is anything like mine you'll need at least a 23p 3 blade stainless prop. I'd like to try a 25p at some point.

Have fun and good luck.

 

[JETDOC]

i would try out 4 blade stainless 21-23 p. some marinas will let you try out different props to see which you want to buy. the 4 blade will give you a much better hole shot for towing & will only lose about 2mph top end. I used to have a 20' four winns with ford 302 & upgraded to 19p 4 blade stainless from 3 blade 21p alum, top speed went from 49 down to 47, but got out of the water & on plane very quick.

 

[Dominic]

bkaltec,

Your boat sounds sweet! Mine is SUPER QUIET, compared to yours. Already looking at a stainless 3 blade 22P prop. Once i make my decision on pitch, amount of blades and such, i will buy one and see how it does!

Thank's for everyones help!!!

 

[keith2500hd]

the hub could have overheated from improper pitch, the hub and blades would show signs of cavitation errosion. having someone with similar boat helps, would try 23-25pitch like previous post.