1968 Jupiter Motor Transplant

[Saint18z]

Hi Guys,
I am moving this from the mercruiser I/O page, because they said you guys could probably be of more help...so here it goes:

I am currently working on a Starcraft Jupiter V, and need a little advise on how to proceed. I am some what new to the boating world, and most of my previous experience has been with OBs. The problem that I have is that I am lucky enough to own a boat with the Mercruiser 80HP Renault motor in it :-(





The boat was bought new by the PO, and saw maybe a years worth of usage back in 1971, then was moved into the garage where it stayed until my family bought the house about 10 years ago. I have never had the boat running, or put it in the water, but when I first started working on it, it would turnover. Unfortunately it sat for a winter without the spark plugs in it, and as a result it will no longer turn over.

Now I am trying to look at my options. Ive got a Mercruiser 120HP 3.0 lined up from a guy locally....actually its an entire boat. The problem with this boat is that the PO must have crashed into some rocks or something because the outdrive has the mounting points for the trim cylinders sheared clean off. Looking at it, it appears that the entire housing is cast aluminum, so I doubt there is any repairing that.

My other option is to try and get the old Renault running....From what ive read (and there isnt much to read about these motors) it seems as though most parts are no longer available. I have had the cylinders soaking with marvel mystery oil for the last few months now, and i still cant seem to get the starter to break them free. Currently I am trying to pull the motor out so that I can attempt to turn the fly wheel over by hand.

I would really like to get the Renault running because it is in perfect condition, but it seems as though its going to be really hard to find any information on it.

So my question is, how hard would it be to repower the boat with a Mercruiser 3.0, I think it will help that I have got everything from the donor boat. Also is the outdrive repairable? I am guessing No, but does anyone have experience with welding on the cast parts? Finally mounting the motor is going to be my biggest challenge, it looks like the 3.0 is quite a bit larger than the Renault, and the mounting is completely different. For example, the aluminum block Renault is mounted off the transom and actually hangs in free air! So to put the 3.0 in I am going to need to build some sort of front motor mount, has anyone done this before?





Thanks,
Chris

 

[starcrafter65]

Re: 1968 Jupiter Motor Transplant

I replaced the entire drivetrain on my 68 Holiday from a 2.5 with MC drive to a 3.0 with an Alpha 1. The bottom line is everything is possible.

What out drive is paired with your Renault? Looks like a Merc....

My suggestion - work with a professional - I am fairly handy around motors etc - but I found a mechanic who did marine on the side - we worked together and I never would have pulled it off myself.

You need to have a pro assess what your options are - maybe that Renault will work rather well - maybe a 3.0 can be dropped in and mated with your current outdrive - maybe the outdrive on the donor is shot - or maybe it can be fixed easily.

Tough to tell through the internet...

 

[jbcurt00]

Re: 1968 Jupiter Motor Transplant

I've read quite a few SC threads, and have never even heard of the small Renault engine you're referring to. And it looks like its in unbelievably good shape. It would probably move a 16' Jupiter fairly well being aluminum & light weight compared to a 4cyl merc.

If it's salvageable, run it if it doesn't cost a fortune to get it running. But yeah, spare parts are probably going to be scarce. Parts & an unusual motor would make me think checking in w/ a marine mechanic, might be a really good idea. Either to do no further harm to the engine, covered & missing a plug for 1 winter shouldn't be too bad, but it certainly could be given the right set of circumstances, and to help figure out why when it turned over it didn't fire.

You can read thru some of the threads here, or in the Starcraft Owners group forum. Going from no motor mounts to fabricated motor mounts is much different then changing existing mounts to accomodate a larger motor. It can certainly be done, some may have done it.

I don't know it there are any OB Starcraft conversions to I/O, but if so reading thru them may help. There are certainly quite a few I/O conversions to OB.

BTW: The iBoats server thought that all of these threads would be helpful, and posted them at the bottom of your thread:

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• [h=6]Offical last year for boat, is an I6 a good motor to transplant?[/h] By rocket1968 in forum Mercruiser I/O & Inboard Engines & Outdrives
  
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[Saint18z]

Re: 1968 Jupiter Motor Transplant

What out drive is paired with your Renault? Looks like a Merc....

It is in fact a merc outdrive, but unfortunately it is what I believe they call a Zero drive, and is only compatible with the Renault motor:





Unlike the newer out drives, this one attaches using four bolts instead of six. Also the drive shaft that comes out of it has a tiny spline on it, so I doubt it will mate up with anything else.

Do you have any links to an OB conversion? I would really like to keep this boat as an I/O but if an OB conversion is cheap and easy, I might go that route.

Thanks,
Chris

 

[jbcurt00]

Re: 1968 Jupiter Motor Transplant

Do you have any links to an OB conversion? I would really like to keep this boat as an I/O but if an OB conversion is cheap and easy, I might go that route. Thanks, Chris

Not particularly, unless you have a 65-90hp motor already, and can weld aluminum.

Here's the last convert I followed, there are others, some glass & some tin...... Much bigger hull, and he's got access to an incredible shop, and can design & weld very well.....

 

[Saint18z]

Re: 1968 Jupiter Motor Transplant

Not particularly, unless you have a 65-90hp motor already, and can weld aluminum.

Well I can weld aluminum....but dont have a motor already. I think I am going to continue to pull the Renault and see if I can get the pistons freed up. Does anyone have experience with this? I am worried that when I turn the flywheel, I might score the cylinders.....Will filling them with oil first help prevent this?

 

[GA_Boater]

Re: 1968 Jupiter Motor Transplant

Saint - I think you are starting to see why some of us call this old boat affliction "madness". Yes, indeed you have a Mercruiser with a Renault engine. And I don't know if you searched the WWW but there is information out there. Parts can be problematic due the age and relative rarity.

Since you said the Jupiter was put to bed in 1971 in a garage, the boat is probably in decent shape and worthy of a transplant. Myself, I wouldn't buy a donor with a busted outdrive. Find a boat with a running motor and complete undamaged drive. They are all over the place and can be found with some diligence. The bad news is nothing is interchangeable. These were Mercury Marines first I/Os and when the switch was made to GM power just about everything changed. I would look for a 110 or 120 M/C - More power than the Renault but not too much power to overwhelm the boat and parts are available.

I have one concern - You said the boat came with the property 10 years ago. Did you get paperwork and do you have legal ownership? I don't know where you are located but in the eyes of the law, depending where you live, you may not "own" the boat. Before you put one red cent into her make sure you can pass legal muster. The forums are filled with "How do I register my boat" threads and many end up as horror stories. I don't want you to be one of them.

I hope all works out and you get the Jupiter on the water. Welcome to the madness we call Starmada. Good luck and have fun! Hope to see you on the water.

 

[Saint18z]

Re: 1968 Jupiter Motor Transplant

I have one concern - You said the boat came with the property 10 years ago. Did you get paperwork and do you have legal ownership? I don't know where you are located but in the eyes of the law, depending where you live, you may not "own" the boat. Before you put one red cent into her make sure you can pass legal muster. The forums are filled with "How do I register my boat" threads and many end up as horror stories. I don't want you to be one of them.

I hope all works out and you get the Jupiter on the water. Welcome to the madness we call Starmada. Good luck and have fun! Hope to see you on the water.

I appreciate your concern, and that was a major one of mine, as soon as I decided to start working on the boat that was the first thing I did. A few snap shots of the s/n on the boat and trailer, and a quick DMV search that showed no records of the boat being registered in the last 30years and I was out the door with a title and registration in my hand (oh yeah and about $200 in taxes and registration fees)

I agree with the finding a good donor boat, The one I am looking at is a 72 Mark Twain. The out drive has issues, as I said the Trim mounts on what I believe is the Gimbal are sheered off. I will upload a picture later. I dont know if this is repairable or not....or if i might just be able to find a new gimbal somewhere. The donor boat owner is asking 600 OBO for the whole thing, and it comes with a 17' 89 trailer which is in decent shape. The other nice thing is that it has a pair of new wise seats in it which I can put into my 72 Super Sport, so i figure I am paying retail on the seats ($400), and $200 for a trailer which I think I can resell for about $400....so I guess I would only be paying $200, but I have yet to hear the motor start.

My SS:

Anyone know where I can find new starcraft decals for the boat?

Thanks,
Chris

 

[GA_Boater]

Re: 1968 Jupiter Motor Transplant

Decals are on eBay and other places. Some of the guys have links to the sellers.

Are the pics of your SS. Nice! There are some other NY Starcrafters in the forum.

On that donor with the busted up outdrive - forget about it. you will end up with a motor and still need an outdrive. If the boat hit something with enough force to rip off the the trim cylinders there is more hidden damage. I seriously doubt if anything will match between the old and new.

In my earlier post, I forgot to say about freeing a stuck motor - ATF/kerosene/Marvel Mystery oil mix has been used by some. pour it in the spark plug holes and wait about a week. Then try to gently turn the crank. Repeat several times, it may work. Search the forums or post in the Mercruiser forums about freeing up a stuck motor.. Don't hold out a lot of hope though. Even if you get the motor to turn, the rings/pistons/cylinder walls are probably shot. After sitting for over 40 years it may be one big rust glob in the cylinders.

Glad you took care if the paperwork part. At least you can sell it if you have to. Last resort only though. Again - Good Luck!

 

[starcrafter65]

Re: 1968 Jupiter Motor Transplant

Chris - Where are you in NY? Looks like Albany - ADK?

 

[Saint18z]

Re: 1968 Jupiter Motor Transplant

Chris - Where are you in NY? Looks like Albany - ADK?

Good guess! I live right near Saratoga Springs, and the boats live up at Schroon Lake. The SS was my grandfathers, and after he passed away, I have been taking care of it so all 9 of his grand kids (including me) can still have a good time out on the lake.

Does anyone know anything about the volvo penta I/O, there is a boat near me with one in it for $300.

 

[jbcurt00]

Re: 1968 Jupiter Motor Transplant

Starmada logos can be found here and just do an ebaymotors search for Starcraft, lots of good stuff will pop up logos & graphics and other SC stuff