Mystery Engine

[jonesym33]

Hi Folks. I'm totally new to the boating world and am starting off with a bang. I bought a '54 cedar and mahogany runabout that was falling apart, and have been restoring it. The thing is I can't figure out what year and model the engine is. It looks like a '55 johnson 25, but none of the other 25 hp parts I have found fit on it. there is a freeze plug looking thing with the sn 1399807. I don't know what else to look at. The plate that has the model # is wrong. Is there any info anyone could give me on this? Any info that I could provide that could help? I need to get at the very least a recoil starter for it.

 

[JB]

Re: Mystery Engine

Hi, Jonesy.<br /><br />Welcome to iboats. <br /><br />Tell us what the model number plate says. How do you know it is wrong? The mount that it is on has to be compatible with the rest of the engine and that could help us zero in a lot.<br /><br />Why do you say it "looks like" a '55 Johnny 25? That would be a model RD-17 or RDE-17. The RD series started as a 25hp in 1951, was upped to 30 hp in 1956, 35hp in 1957, 40hp in 1958, and was still in production as a 40hp in 1964. Many parts were changed over the life of the series.<br /><br />What color is (was) it? What parts did not fit on it?<br /><br />Let us know so we can be of more help.<br /><br />Good luck.

 

[jonesym33]

Re: Mystery Engine

the plate says rd-17. The engine cowl is sea green and says johnson 25 on it.<br /><br />the thing is I bought a seal kit for the lower unit for that size engine and it didn't fit, and I bought a recoil starter for a 25 and it didn't fit either. the powerhead looks like it used to be Red, its sea green now. some other clues. The recoil starter mounts are 10 inches apart across the engine, and those mounts are about 12" from the bolt hole on the other end of the engine.

 

[rolmops]

Re: Mystery Engine

The RD17 is a green colored 1955 25 horse Johnson.You will have to buy the seals and parts that fit that model.Since you are in Texas,I will leave it to Texas board members to direct you to a place where you can get a manual and parts for your engine.The ones That I know are in Minnesota and upstate New York.

 

[jonesym33]

Re: Mystery Engine

I've already looked up and purchased parts for the RD-17 and they don't fit. Maybe the seller has their info wrong? The recoil starter I got for it is 8 inches across when it comes to the bolt holes across the front of the engine. the P/N is 306084. I also have another recoil starter for it that looks completely different but has the same issue. too small.

 

[Paul Moir]

Re: Mystery Engine

Jonesym33 - I think I might be onto something. What's the serial number on the nameplate?<br /><br />Also, there's been some trouble with the aftermarket lower unit seal kits. If you have 18-2686, I think the propshaft seal won't fit.

 

[jonesym33]

Re: Mystery Engine

12611980

 

[Paul Moir]

Re: Mystery Engine

The serial number on the engine block seems to me to be a 1956 30hp serial number. The '56 through '58 Johnsons were painted 'holiday bronze' - a maroon colour.<br /><br />1397187 - '56 30hp Javelin<br />1397635 - '56 30hp Javelin<br />- Your powerhead here -<br />1458370 - '56 30hp Javelin<br /><br />Can you determine if the midsection and lower unit are from the '55 or '56 engine?<br /> '56 30hp<br /><br />(Sorry - no 25hp picture...)<br /><br />PS - I've got a early '60s 28hp engine (35.7CID block reborn), but my pull start measures 9.5" across and 10 3/4" + 11.5" to the back bolt. I think probably your little pull start might be from a late '60s 25hp (22.0 CID block).

 

[jonesym33]

Re: Mystery Engine

how can I determine this? Also, if is sounds like a 30 hp powerhead what does that mean in regards to getting an electric starter setup? will the 25 setup fit?

 

[Paul Moir]

Re: Mystery Engine

Try to see if the midsection and lower unit look like they've been repainted from red. But I think the most likely thing is that the powerhead got switched rather than the transom clamp assy.<br /><br />I'm not sure about the starter setup. Hopefully someone who knows will be along. There were some big changes over those two years, so mabey not. I belive the '55 starter setup is 6v only, where the '56 is 12 or 6. The 6v starters are larger than 3.5" in diameter.

 

[rolmops]

Re: Mystery Engine

The red block would make it either '56 30 horse or '57,'58 35.tricky business.

 

[Paul Moir]

Re: Mystery Engine

Good point rolmops - <br /><br />To rule out a '57 or '58 35hp, have a look at the head where the spark plugs get bolted in. If that piece has two cap bolted on, sticking out about 3/4" right of the spark plugs, then the engine has compression relife to make it easier to pull start. The '56 30hp did not have compression relief, while the 35hp engine did.

 

[R.Johnson]

Re: Mystery Engine

Is that cedar, and mahogany boat a Dunphy by chance? If the boat has a name plate, let us know what it is. It would be great if you could post a picture of the whole set-up.

 

[Chinewalker]

Re: Mystery Engine

Okay, time to clear this up.... The '55 25hp was VERY different from the 1954 & prior model 25hp, which would explain why your recoil didn't fit, eithe that or it's from a late '60s or later 25hp. The block serial is 1956 30hp, while the clamp serial is '55 25hp. The main differences aren't visible from the outside, as they made changes to the inside to gain the extra five ponies. The '56 30hp has a 6:1 compression ratio, while the '55 has a 5:1 compression ratio. The cylinder head dome and the piston domes are different to account for this. They also changed the wrist pin bearing arrangement, and made the intake holes on the reed plate a hair bigger. These parts are all interchangeable as a unit, .ie if you swap '56 pistons into a '55 block, you need to swap the head, too...<br /><br />With the proper bracket for the starter, it is quite easy to convert a 6V system to a 12V starter system. The choke solenoid need not be replaced. The best way is to use a '57 35hp electric belly pan with the nifty little plug in the side to get around the cables exiting from the hole in the belly pan on the '55/'56. The electric start flywheels are interchangeable as the ring gears remained the same.<br /><br />The '56 30hp is a very robust powerhead and will take a fair amount of abuse. I've run several over the years on a 36-class Utility - and have run it quite hard. On a light hull, there is a noticeable difference between the 25 and 30.<br /><br />Have fun!<br />- Scott

 

[jonesym33]

Re: Mystery Engine

OK after all this I'm pretty sure I have a 56 30 hp powerhead. The lower unit, mid section, and cowl don't look like they've ever been red. So maybe they only switched the powerhead? I have turned the thing over and gotten it started in a trashcan of water. Seems to run really well though Idleing I haven't figured out. I'll go through the archives on that. Also..... Is the cowl between the 55 25hp and the 56 30 hp different? It occurs to me that maybe the reason they only have the old rope starter set up on it because the recoil may not fit under the cowl? <br /><br />(EDIT: Sorry, Smitty. Soliciting to buy or sell is not allowed on the Forum. Try the iboats Want Ads, http://www.iboats.com/boats/marine--1/boating_want_ads--108 or www.twincityourboard.com for used parts.) <br /><br />This thing is total murder starting with the rope starter. I'm a small guy and I'm not comfortable trying to run this thing on the lake like it is currently is set up.<br /><br />also, thanks for the info so far. This group is invaluable

 

[Chinewalker]

Re: Mystery Engine

Hi Jonesy,<br /> I think you might find the pull-starting easier to do once it's on a boat and you're able to leverage it a bit better. Still not easy, but easier. The cowlings are cosmetically a little different in casting, but otherwise are functionally the same and interchangeable. The '55 25 and '56 30 use the same recoil, part for part. The recoil is also functionally the same as those used on the 28, 33, 35 and 40hp models up into the late 1960s, although some have lifting rings cast in, and some have means for a compression release.<br />- Scott

 

[jonesym33]

Re: Mystery Engine

New question.<br /><br />Is there a resource for part #'s online? I need to get the part #'s for the recoil starter and a 12 v bracket. I also need to know what kind of solenoid would work. I need to get this thing to start without using that damned rope.

 

[jonesym33]

Re: Mystery Engine

P.S. here is a picture of the boat I've been working on. This pic is a month old or so but it gives an idea of what I'm trying to get on the water.<br /><br /> http://www.myfishingpictures.com/watermark.php?file=527/5277recent-med.JPG

 

[Jcrain]

Re: Mystery Engine

Nice looking boat. What part of Texas you in?

 

[jonesym33]

Re: Mystery Engine

Thanks, You should have seen the before pictures. It was fiberglassed from bottom to top, painted black and white and had been sitting in a junk yard for 8 years. It also had a gargantuan rotting plywood framed windshield. The fiberglass on the bottom looked like lemon merengue pie.<br /><br />I'm an Austinite.