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Problem at higher speeds

dickdl

New member
Once I reach a certain speed &

Once I reach a certain speed (doesn't matter if I accelerate quickly or slowly) something seems to kick out. Seems like a clutch lets go or something liek a clutch. The engine revs but no thrust. Throttle the engine down and it takes off again. I have a 1993 Mercrusier 350 (v8) with Alpha Stern Drive. Can anyone tell me what is wrong? Is it going to invovle a major repair?

Thanks
 
Could be your prop hub or your

Could be your prop hub or your engine coupler.
Try a different prop to confirm which.

If its the coupler it involves engine R&R to change it out. Still less than a million.

Rod
 
Could be your prop hub or your

Could be your prop hub or your engine coupler.
Try a different prop to confirm which.

If its the coupler it involves engine R&R to change it out. Still less than a million.

Rod
 
I'll try the prop first. T

I'll try the prop first. The current prop ispretty beatup and I could use a new one anyway. I know nothing about props and it appears there are lots of different things to consider. How do I determine the best prop for my boat?
 
"Insert your data in the sprea

"Insert your data in the spreadsheet compliments of Rod S. It will get you into the ballpark.

<center><table border=1><tr><td>http://www.marineengine.com/discus/icons/mime_msexcel.gif""" align=left alt=""application/vnd.ms-excel"">prop finder
[url=""][b]Copy of Boat_Speed_Finder-79780.xls[/b][/url] (22.5 k)</td></tr></table></center>"
 
Might be jumping out of forwar

Might be jumping out of forward gear as you tilt up the engine accelerating...check the cable settings.
 
I put in correct weight and HP

I put in correct weight and HP and according to the spreadsheet (thanks for posting that) I need a prop with 16.7 pitch (assuming I have a 1.47 drive ratio which I have no clue about). Does that sound about right? Current prop has 3 blades. Any advantage to replacing it with a 4 blade prop? Any recommendations of a good place to purchase a replacement? Sorry for all the questions. As I said I know nothing about this.
 
Lamar;
Most 5.7's can run


Lamar;
Most 5.7's can run at least a 19" pitch with a 1.47 ratio drive; which is the right ratio for a 5.7 BTW.
Give me your specifics and I'll run it for you.
Boat type & length?
Boat empty weight?
Rated hp? 260?
Altitude of lake above sea levell?

Rod
 
I have a 1993 JC Tritoon
It i


I have a 1993 JC Tritoon
It is 26 feet long

I am not certain but I think I was told the empty weight is 4400 lbs.

It has an alpha one stern drive

Altitude here is between 889 feet.
 
Lamar;
I ran the data and I a


Lamar;
I ran the data and I also get a 16" prop.
I would try a 17" pitch to start with and see how that works for you.
You should be able to hit about 44 mph top speed with that.

Rod
 
A guy told me how to check and

A guy told me how to check and the current prop is a 17 pitch so I'll go with that.

Thanks for all the help.
 
The new prop fixed the problem

The new prop fixed the problem so I am happy that it wasn't something more expensive. I did note that 4100 rpm and 28 mph seems to be top end. Since Rod thinks I should get 44 mph I am wondering why the difference. Any ideas?
 
"Tritoons have completely diff

"Tritoons have completely different speed characteristics than conventional V type hulls and usually run considerably slower than a boat for a given HP. In past, what speeds did you attain? Do you have any reason to feel you are actually slower then with original prop?
Of course I could be wrong, but I would not be expecting anything over about 30 based on experience with friend's 'toon style vessels. My V-8 powered V-bottom houseboat (heavier I know) only hits 8 mph running at its best."
 
"Lamar;
Sorry I know nothing


"Lamar;
Sorry I know nothing about the characteristics of a Tritoon hull, and I note David's comments about their lack of speed.
Based on your 4100 Rpm at WOT, you could even drop down to a 15" pitch prop easily, but if the 17" is working for you, then life is good.

Rod"
 
David / Rod

I don't thi


David / Rod

I don't think I did any better with the origianl prop. Didn't mean to imply that the new one was worse. Sounds like that is about all I can expect. Thanks for the info and help.
 
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