switch a jet to a prop. lower unit?

[ss16]

I have a mid 80's 25 hp merc. jet and it does not push my 16ft. aluminum boat fast enough. I understand it losses hp. from being a jet drive. So I would like to know how hard it would be to change it to a prop. lower unit and if its worth the investment instead of selling it and buying a different motor.

 

[Yepblaze]

Re: switch a jet to a prop. lower unit?

Switching out a lower unit from jet to prop should be no problem.

But......

As I have seen on some boats when switched over to a jet the transom height becomes an issue and is adjusted accordingly.

If your boat has a standard transom height I don't see much of a problem.

 

[dajohnson53]

Re: switch a jet to a prop. lower unit?

Switching out a lower unit from jet to prop should be no problem.

But......

As I have seen on some boats when switched over to a jet the transom height becomes an issue and is adjusted accordingly.

If your boat has a standard transom height I don't see much of a problem.

Ditto here - if the jet unit was added "after market" and the engine itself has all the parts necessary for neutral and reverse.

IF it was a factory built jet, although the jet unit is the same as aftermarket, but the engine itself might *(I say MIGHT - you have to check) not have the parts to have a reverse or even a neutral gear in a conventional lower unit.

As you know, with a jet lower unit, the engine always operates in forward, even when in "neutral" and reverse. Reverse is simply the reverse-boot device cupping over the jet outlet and directing the output forward, and "neutral" is simply adjusting that boot so that it balances between forward and reverse, neutral in the water, but not neutral at the drive shaft.

In general a "factory jet" will have the jet unit painted the same color as the engine (i.e. Mercury Black). The after market jets are usually red in color. There are exceptions to this rule though - AND, factory jet doesn't necessarily mean the reverse and neutral capability isn't there, but you have to check.

 

[ss16]

Re: switch a jet to a prop. lower unit?

I'm pretty sure it's a factory jet and I have called a local mercury dealer. They told me it would be more benificail to me to buy another motor and trade in or sell this one. I just thought they were trying to sell me a new motor. I really don't want to do that cause most dealers sell 4stroke engines and they really don't impress me much. I know there quiter and better on fuel but to get the same h.p. the weight and size almost doubles. THanks for the info guys. I'll look into those things.

 

[dajohnson53]

Re: switch a jet to a prop. lower unit?

I'm pretty sure it's a factory jet and I have called a local mercury dealer. They told me it would be more benificail to me to buy another motor and trade in or sell this one. I just thought they were trying to sell me a new motor. I really don't want to do that cause most dealers sell 4stroke engines and they really don't impress me much. I know there quiter and better on fuel but to get the same h.p. the weight and size almost doubles. THanks for the info guys. I'll look into those things.

I'd be interested in hearing what you find out. YOu might be able to tell by taking off the cowling and looking to see if there's the linkage for the forward/reverse mechanism under there - if you kind of know what you're looking for.

I didn't mean to be a nay-sayer, but I've been running outboard jets for about 10 years and am aware that some "factory jets" essentially can't be converted to props. All of mine have happened to be after market conversions so it's just a matter of replacing the lower unit and moving the shift cable from the jet unit to the linkage inside the cowling. (assuming remote controls).

For what it's worth - around here, excellent used 25-40 hp engines seem to be pretty reasonably priced, They don't demand premium prices like the 10-15 hp kickers (which seem to be much more in demand). You might be able to pretty easily replace that engine with a conventional set up for what you could sell it for, since the jet might be a little more valuable to someone who needs one, since they're not as common.

 

[ss16]

Re: switch a jet to a prop. lower unit?

Hey dajohnson53. sorry I didn't reply sooner but got caught up in other projects I checked under the cowling and found out it was a prop. motor from factory. I went further and looked at the paint on the jet and found it was painted black over the red paint. Thanks for the info. I may just get anouther motor anyway, because like you said 25-40h.p. are pretty reasonable and I could easily sell this one .

 

[dajohnson53]

Re: switch a jet to a prop. lower unit?

Cool. Good luck whatever you do.