1956 Fastwin and Newer Compatibility

[rjezuit]

Would a 1957, 58, or 59 power head from an 18HP Fastwin fit on the leg from a 1956 Fastwin? And by the same token would a 20 or 25 up to around 1972, would it fit on the 1956 leg? I realize the exhaust tube and gasket is different, but would they bolt on? Looking to get up to the 22 CID from the 19.94 Thanks, Rick

 

[steelespike]

Re: 1956 Fastwin and Newer Compatibility

Are you trying to get more hp and the same 15hp look?As far as speed the 15 is rated for 25mph the 18 27.not moch improvement.
Otherwise it would seem it makes more sense to simply find a 22 cube motor.
The 25 is almost the same weight as the 18.There are also the possibilities of miss matched drive shafts shift linkage and water tube connections not to mention exhaust routing.Later years may have different gear ratios.

 

[F_R]

Re: 1956 Fastwin and Newer Compatibility

Pretty sure the '57-58 will bolt right up. '59-up was the fiberglass cowl and there might be a difference with the 3 front bolts/studs. I can't say for sure without looking. For sure, the mounts for the aluminum hood won't be there. And you can't use the 15hp head (hood mounts) on an 18, if that's what you are thinking. Also, Johnson has different hood mounts than Evinrude, so watch it if that is what you're thinking.

 

[samo_ott]

Re: 1956 Fastwin and Newer Compatibility

Interesting question. I have all of those but have never tried to swap em around. The 22 cubes are very common though. Used from '57 til the early 70's... and the 57 and 58 fastwin look very similar to the 56 fastwin... what exactly are you trying to do? The 19.94 performs very very close to he 22 cube as I had both on my boat this year and I was surprised how well the 19.94 performed...

 

[jay_merrill]

Re: 1956 Fastwin and Newer Compatibility

I'm dealing from memory only here, but isn't the '56 a 15hp engine? If it is and is the one I am thinking of, I've always thought of it as a very strong motor. When I was a kid, one of my friends had one and I could never tell the difference between it and the later 18hp motors.



???

 

[jbjennings]

Re: 1956 Fastwin and Newer Compatibility

I've got a '56 evinrude 15hp and a '57 and '58 18hp. Although the 15 is a strong runner, my 18's are obviously more powerful and usually go about 4 to 6mph faster on top end. I do like the 15's a LOT because they seem particularly smooth running. I have a '54 fastwin 15 also, and it DOES seem to be darned near as powerful as an 18hp. I don't know why, but the '53 and '54 10hp OMC motors seem to noticeably more powerful than the later ones.
I've been very interested in getting a '69-'72 25hp powerhead and putting it on a '57 18hp midsection. It will bolt up, although I was told there was a couple of small problems that aren't that hard to whip, such as fixing some "ears" on the head to mount the '57 cowl onto. I'd like to braize some ears on a 25hp head and put it on the '57. I'd just like to do it for fun, and have kind of a sleeper '57 "18" hp motor. I'd get a kick out of it keeping up with the modern 20 and 25hp motors, if it would.
Problem is, I haven't found a 25hp powerhead cheap enough yet.
Later,
JBJ

 

[R.Johnson]

Re: 1956 Fastwin and Newer Compatibility

Check and see if the power head to exhaust housing gasket has the same part number. If they do, it should bolt up.

 

[Chinewalker]

Re: 1956 Fastwin and Newer Compatibility

Easiest sleeper would be to put a '57 or '58 18hp powerhead on the '56 chassis. Later powerheads would require a bit more modification to accomodate the cowling. Not sure the thermostat head would clear the cowling, either.

Might be able to modify an '57/'58 18hp powerhead to accept the later 25hp innards, which would also mean modifying the head to the same shape as the 25hp head so the pistons didn't hit it. Lots of stuff you can try if you've got the parts to mix and match with...

 

[steelespike]

Re: 1956 Fastwin and Newer Compatibility

I'm wondering if there would be a gear ratio problem.The 56 is .572,the 71 18 and 25
are 12/21 I don't know if these numbers work out the same?Do you devide 12 into 21?
Probably not as much fun; but wouldn't it be easier and faster to get a 70 or 71
25 hp and change the decals or cowl?

 

[rjezuit]

Re: 1956 Fastwin and Newer Compatibility

My thoughts were to get more power in the 1956 package. The '56 motor I have is a whole lot better looking then the '59 and newer models. I really would like a early 70's 25Hp, but they are not easily found around these parts (at least reasonably priced). I guess I am kind of partial to the Evinrude blue color. I picked up the '56 with a stand and tank for $!50 2 years back, but I am a little bit underpowered. The 18, 20 and 25 are similar in size and weight, so that is what I had in mind. Plus the sleeper aspect seems kind of cool. Rick

 

[kbait]

Re: 1956 Fastwin and Newer Compatibility

I fixed a '56 fastwin 15 to sell this summer. When I tested it on my boat, it performed like my '75 15hp speedwise, but not quite like my 18 fastwin ('66). Close though. I'd say 19 vs. 21mph (not verified..). Not sure if props were same pitch, but I believe they were both standard for their motors.. Heck, maybe 24/1 vs 50/1 fuel mix makes it even more of a wash? I was actually quite impressed with that old 15 fastwin! Sounded kinda like an airplane taking off

 

[rjezuit]

Re: 1956 Fastwin and Newer Compatibility

Will an 18HP head from '57 bolt up to a newer 25HP from the late 60's early 70's?
Then I could put a 25HP block on with the '57 or '58 head and have the mounting for the cowl correct. Rick

 

[jbjennings]

Re: 1956 Fastwin and Newer Compatibility

Will an 18HP head from '57 bolt up to a newer 25HP from the late 60's early 70's?
Then I could put a 25HP block on with the '57 or '58 head and have the mounting for the cowl correct. Rick

I don't believe a 25hp block will accept a '57 head without changing the compression ratio or letting the piston hit the head. Not even sure if the bolt holes will match. If you can do that, I'm in for it too!
Not sure, but pretty sure,
JBJ​

 

[soundchaser]

Re: 1956 Fastwin and Newer Compatibility

I've actually put a 25hp powerhead on a 1959 18hp leg. I cheat a little with my 10hp limit in my area lakes. I took a 1959 18hp johnson and stuffed a 1974 25hp powerhead under the hood, because I could take a 1959 10hp back latching plate that says ten on it. And put it on the back of the 18hp motor and the young rangers have no idea. Of course I stole the 10hp serial# plates so if he looks it up it will come back as a 10hp. So I have a 25hp/10hp 1959 johnson. But if memory serves me, I believe the 15hp powerhead is a slightly different block.

 

[rjezuit]

Re: 1956 Fastwin and Newer Compatibility

If a '57 18hp head will bolt up, I can modify it for piston clearance (at least I think so. Rick

 

[Chinewalker]

Re: 1956 Fastwin and Newer Compatibility

A '57 18hp head will not fit a '59 or later block due to the passage in the block for the thermostat... They won't mate up. The way to get as close as possible to 25 in the 15 would be to put the 25 innards in a '57 block, using the '25 intake as well. You'd have to Dremel out the '57 head to match the dome of the 25 so the pistons will clear properly... If you had a 25 block onhand, you could check the porting to see if there are any changes there, too...

 

[soundchaser]

Re: 1956 Fastwin and Newer Compatibility

Exhaust covers are different.

 

[rjezuit]

Re: 1956 Fastwin and Newer Compatibility

Sounds like a lot to go through. I guess I'll just wait and try and find a 25 HP cheap. Missed one on Craigslist a few months back. 1972 for $175. Was listed and sold within 4 hours. Motors around here last a long time, fresh water and short season. Rick

 

[soundchaser]

Re: 1956 Fastwin and Newer Compatibility

must be nice to be able to find those pretty motors. here in new jersey you need a miracle to get a bolt out

 

[rjezuit]

Re: 1956 Fastwin and Newer Compatibility

My '56 sat in a guy's basement for 14 years. He bought it from someone who said it sat for years. Other than dried on oil and crud, it looked great. A little WD-40 and a rag put it in tip top shape. I replaced the impeller and took it out, started right up.The first winter I replaced coils, points and condensers and added a kill switch the second winter. This spring, I pumped it up the first time and it took me 2 pulls for it to start. Usually starts on 1, even my teenage daughters can start it. It's a great motor, just need a little more power. Rick