1958 johnson 18hp wont plane

[henry954]

Re: 1958 johnson 18hp wont plane

Man that is the last thing I wanted to hear today. Guess ill start looking around for that extension. Thanks for hangin with me and helping me along.

 

[64osby]

Re: 1958 johnson 18hp wont plane

furthermore just went downstairs, started it ...

Is this in your basement? Are you running it in a tank?

Post a pick of the whole transom, someone might have some ideas other than finding a long shaft extension.

You could probably buy a long shaft for the cost of the parts to convert. Post an ad to trade a short shaft for a long.

 

[phillnjack2]

Re: 1958 johnson 18hp wont plane

woh woh woh there cowboys.
this engine will be fine, i know its a short shaftand the boat takes a longshaft normally.

Now go make a nice strong setback to get that engine back away from the boat by around 5 inches.

there are lots of guys running short shaft motors on longshaft boats, mine is a long shaft on longshaft and to get more speed i have to jack it up and move it back to get what you already have !!!!!!!!!!!!!!!!!!
ok so it dont make sense at first, but what you need to do is get the engine away from the boat.
there is setbacks on the market from about 2 inch to 36 inch long ,yep 36inches for the big stuff.

By moving the engine back away from the boat your putting the prop in clean water, and you having a shortshaft engine means it dont need a jackplate.
as it is youl never get the performance from the engine.

Get some 5 inch chanel about 1/4 in steel or 5/8 if alluminium and just make two simple plates for the back of that boat and it will plane easy.

ive got a couple of pics of what i just made, but i also had to make my engine higher up due to it being longshaft.
if mine was shortshaft the plates would just be oblong boxes.

hope these pics show what i mean.
1 pic is my 60hp rude and another is a yamaha on someones john boat both longshafts,so thats why we had to go higher.
remember you only have to go back and not make engine go up anymore than it is now.
.

 

[henry954]

Re: 1958 johnson 18hp wont plane

Phil, don't know if I want to make that commitment. Sounds like a great suggestion but going to save that for last. cant sell this boat as I like the depth of the inside so I have to make it work. definitely keeping the motor, it seems to be very robust.

 

[Chinewalker]

Re: 1958 johnson 18hp wont plane

A long shaft kit should be fairly easy to find and not hard to install. FAR better option than trying to cobble some bracket together or cut the transom. The problem with setting the motor back far enough to get "clean" water is that it's a tiller motor and you'll tire quickly of reaching back that far to steer, shift and operate the throttle. That gets you into adding tiller extensions and even more complication. Just get the long shaft kit. Same one used for 20 years of 22-cube motors from the 1950s into the 1970s. You need the extension housing, driveshaft, shift shaft extension, water tube extension, and the extra long rear bolt. Check eBay, AOMCI.org, and even your local dealer.

 

[phillnjack2]

Re: 1958 johnson 18hp wont plane

Dont sell the boat , and do not sell the engine.
and dont go paying out fortunes for longshaft kits neither.
just make a simple stand off bracket for yours and make it stand off 5 inches and youl not only have the right length motor, but
it will out perform a longshaft directly on the transom.

as for needing longer tillers etc, since when is a piece of plastic tube gonna cost a fortune to slip over it ? (white kitchen pipe !!!!)

the resuts by adding a small setback far outweigh any mods to the engine, you dont need any special tools, and dont need to
make it as strong as the ones i made.
your only talking of 18hp so make it strong enough for a 30hp and you have huge margin for strength.

if you have any angle alloy around then make it from that.
you can buy them but i just think its a waste of money when you will definitely find something to do the job just lying around.
it can be made from wood as long as you make sure the box structure has some metal on the edges to keep it firm.

i wish you lived close i could knock you one up in 5 mins flat and fit it as well for free as its a easy simple thing to do.

go have a look at these, you can mount these upside down to give you what you need, these cost $99 but can be got real cheap secondhand or just make them yourself.
here is a link to them to show what they are
Mini-Jacker

most people buy these to make their longshaft act like a shortshaft !!!! this gives them more speed and better all round handling.

under no circumstances cut your transom, that would be crazy and ruin the boat.

you just need a metal box type structure on the back to get the engine away from the boat, idealy 5 inches.
if you have some long metal stud thread you can even use 2 x 5 inch blocks of wood to get it back far enough.

by doing this you get more performanceand more room in the boat as well, its a no brainer.
if i could swap my longshaft midsection for a shortshaft that would fit my engine i would do it straight away.

go look on youtube at the boats they run on the sabine river, it will show you just what jack plates do on johnboats and flat river punts.
with it back a bit you gain around 8 to 10% top end straight away compared to normal longshaft sitting on there !!!!!!

you choose what to do as its your boat and engine, i would go the cheap simple route and keep both the boat and engine the
way they were from factory and just bolt on a bracket.

and one very major factor that often gets forgotten , this means you can run in water 5 inches shallower than a normal set up !!!!

hope this helps

phill

 

[henry954]

Re: 1958 johnson 18hp wont plane

im working with twin city outboards in Minnesota. Sent him pics and measurements of my unit today in order to put together an extension kit.. They haven't got back to me. Seems that they got swamped with business today.Nice problem to have. Also posted at aomci. Thanks guys for all the help. I would never have thought that the transom to shaft ratio would have been a problem. ended up taking apart the gear case. Not bad for 55 year old engine

 

[phillnjack2]

Re: 1958 johnson 18hp wont plane

Well once you get it all running right and on the plane you can then get the prop sharpened up and enjoy the boat.


phill

 

[henry954]

Re: 1958 johnson 18hp wont plane

quick update guys. You were all right. I put together that 5 inch extension and bingo. Was all she needed. but today I ran aground. Didn't know how shallow the river was in this one spot. I spun the prop hub . was able to make it to the lauch at 5 mph. That was a relief. Got home and ordered a prop from this website. 88 dollars shipped. Do they come any cheaper? I got the 11 pitch.

 

[nwcove]

Re: 1958 johnson 18hp wont plane

they do come cheaper.....but as seen many times.....props from ebay etc will often have hub failure after a short time. your new prop will last a long time ( stay off the rocks lol). maybe look into having the old prop re-hubbed..... it may be a cheaper option , and you will have a spare tire so to speak. jmo