converting from I/O to outboard

[macojoe]

Hello i am converting my 20 wellcraft to an outboard from an I/O. I have all ready did the fiberglassing and reinforcement of the transmon. have also got a gill bracket. Now I have to install the gill bracket. I am not sure were to mount the bracket? Meaning the height for the new motor. I am putting a 1994 120 Johnson with 97 hours from a friends boat. Not sure if it is a long shaft or short shaft. Any help with this would be appreciated. Also does anyone no were I could get wireing harness and control box with <br />tilt & trim. My guess is that it will have to be around 20' Thanks

 

[DJ]

Re: converting from I/O to outboard

macojoe,<br /><br />Don't mean to rain on your parade but, that 120 is REALLY going to struggle on that boat.<br /><br />Now, to figure what shaft engine you have, try this. <br /><br />Measure from the top of the mounting bracket to the cavitation plate. If it is a standard shaft, the measurement will be about 20". If it's an X-long, it will be about 25".

 

[Solittle]

Re: converting from I/O to outboard

I second djohns19 on the 120. Give some thought to selling the 120 and going for a 150-175.<br /><br />I have a 23' Wellcraft CC with twin OMC V4 Sea Drives and it will not get up on plane with one engine - it is a tad bigger than yours but - - -

 

[grid]

Re: converting from I/O to outboard

I've found that anytime I do a weird conversion, it helps to contact the builder to find out if they have any experience that may help me. In your case,working backward, the anti-cavitation plate should be level with the bottom of your hull if it were bolted onto the transom. With the Gil bracket pushing the engine back about 3', you should be able to put the plate about 4" higher; if you don't mind slightly slower planing times, then go 6" higher. Check your engine model number to see if there is an "X" in it. If there is, the shaft is 25". If not (and I'd doubt many 120s had 25" shafts), then it's a 20" shaft, and I would not recommend that length for any transom bracket installation.

 

[macojoe]

Re: converting from I/O to outboard

Thank's guy !! And I agree that this motor will be a little slow but being that I am a poor man in a rich men sport money is an issue. This motor comes from a 18 foot Henry O' it has 97 hours on the meter and belonged to My friends 68 year old father from new. Last year his boat broke its moring and slamed into some rocks and was damaged to much for repair. Sold he sold me the motor for $2000.00 Thought this was a deal. But do you guys think I can get away with motor?? I don't care how fast I go i am there for the fun and fish with no clock. But the issue you brought up is that it is a short shaft and is this going to be a huge problem ?? Should I sell this motor and get a long shaft ?? This is a good reliable motor and would really like to use it !<br />Thanks for all help

 

[mellowyellow]

Re: converting from I/O to outboard

how about an adjustable jack plate? <br />then you can manually set engine hieght.<br />good luck,<br />M.Y.

 

[DJ]

Re: converting from I/O to outboard

macojoe,<br /><br />The short shaft will cause problems because the powerhead will always be VERY close to the water. Not to mention your exhaust relief ports will probably covered at all times.<br /><br />All of this becomes apperant because of the geometry of the bracket.<br /><br />Have you thought about selling the boat and getting a smaller one?<br /><br />If you do decide to do it, make sure you prop the motor so that it reaches its full rpm capability at wide open throttle. Otherwise the constant lugging will kill it in short order. You're probably looking at a prop in the 12 to 14" inch pitch range.

 

[ob1jeeper]

Re: converting from I/O to outboard

Odd... I'm seriously considering re-powering from an OB to an I/O. Care to chat about possible swap or sale of the I/O pieces?

 

[macojoe]

Re: converting from I/O to outboard

And I thought this was going to be easy !! What about putting the bracket 4 inches higer Like one of you suggested ?? will this help my problem ?? I really like the boat and have had it for a long time so getting rid of it is not an option. I might have to cosider selling the motor. but this motor is a great motor and I am scared of buying a used motor that I don't no. Am I really wasting my time with this set up??<br />Thanks guy's

 

[DJ]

Re: converting from I/O to outboard

macojoe,<br /><br />You're in experimental territory here. As previously suggested, you could mount a manual jack plate to the bracket. Most jackplates will give you at least 4-5" of vertical adjustment-maybe more. You're really looking for "up" travel.<br /><br />This would allow you to mount the bracket where it is intended to be mounted (you don't want to move that thing around) and still experiment with engine height.<br /><br />The MANUAL jackplate won't set the engine back much farther, maybe 3-4" max.<br /><br />I see jack plates on e-bay, quite often.

 

[macojoe]

Re: converting from I/O to outboard

ob1jeeper I would like to talk to you about buying your outboard. I have an 165 outdrive rebuilt 2 seasons ago and a manafold for the same (chevy 250) a couple of other small parts. but this motor I had was the oring from 1975 so not mush left and the motor was Junk. You can email me at macojoe2000@yahoo.com thanks

 

[macojoe]

Re: converting from I/O to outboard

Ok at what hieight should I mount this bracket on the transmon?? I thought I should mount it at 20" if I was going to put a 20" motor and at 25 for a 25" motor ?? It is a stainless marine bracket: http://www.stainlessmarine.com/single.html <br /> it is the one in the middle of the page with the swim platform on it. it is 26" long so the motor will be mounted 26" form the motor.<br />Could I mout it at the 25" for a long shaft and use the jack plate to lower the motor till I get a long shaft ?? <br />Sorry for all the questions but I have gotten lost on this path!! Thought I was going good till now. Thanks for all your help guys

 

[ledgefinder]

Re: converting from I/O to outboard

Underpowered? An 88SPL Johnson pushed my 19' GradyWhite deep V to 5300 rpm with two adults, two kids & a standard 17" pitch prop. We skiied with no problems, including me (235 lbs) starting on one ski. His 120 is a late model, so bigger than the 99.6 V4s, right? I will admit having questions about power when I was buying the boat, but one ride proved I was wrong.

 

[macojoe]

Re: converting from I/O to outboard

I think the 120 will be fine for what I want. I no of two boats same as mine but were built as outboard's. And they have 135 Mer. on them and they say there great. 150 is a little big has a lot of power not being used on this boat. So I think I could get away with the 120. But I am a bit worryed about the fact the thing will be so close to the water and not sure what to o at this point. Anyone with more advice on this subject please reply !! good or bad.<br /><br />I have a rebuilt (2 seasons) outdrive for a 165 I/O and also 1 year old manafold for chevy 250, gimble ring housing complete with Hydrulic tubes if any one intrested.<br />Thanks guys

 

[ob]

Re: converting from I/O to outboard

macojoe , looking at the picture of transom bracket. Does motor flange have four holes? Looks like two on picture.

 

[clanton]

Re: converting from I/O to outboard

If you call Stainless Marine, they will give you mounting instructions.

 

[ob]

Re: converting from I/O to outboard

macojoe,Without doing as Djohns suggests in obtaining jackplate to utilize with the installation,the only way I see to insure motor height will be within an adjustable range is to mount bracket to motor,using the motors center holes.Lift and position entire unit to transom,insuring cavitation plate on motor is even with bottom of boat.Hopefully that will be suitable location to drll and mount for your transom.Use this position to trace holes or simply locate height for mounting.Using center holes on motor bracket will insure that you have adjustment up and down from the cavitation plate being level with bottom of boat.Since this bracket is prefabbed ,and not specific to your boat you will( as Djohns suggests ) have to experiment with mounting location.This is just my opinion as I see what you have to work with.

 

[macojoe]

Re: converting from I/O to outboard

Thanks guy's! ob the bracket has 6 holes two near the bottom and 4 on the upper part of the flange not shown in the pic. I never thought about calling stainless I will give it a try. I was talking to a buddy of mine and we were talking about doing it like you were suggesting. <br /> I will admitt I am thinking of selling the motor and buy some kind of long shaft. probably a 150 or something. <br /> I really wanted to use this 120 Johnson I no the engin and it is in perfect condition. I know the owner since new and I got it for $2000 I don't no what I am going to get for that kind of money some where else and don't have much more to spend.<br /> But as everyone has said 20" might not cut it.<br />Again Thanks guys

 

[sloopy]

Re: converting from I/O to outboard

You'll be fine! havea blast!

 

[Dhadley]

Re: converting from I/O to outboard

Heres a general rule of thumb:<br /><br />For every 5" you go back with the motor you can go up 1".<br /><br />As suggested always opt a little low. You can always raise the motor either with the mounting holes or by adding the mentioned manual jackplate.<br /><br />Good luck!