1955 big twin

[Bigtwin55]

I just picked up a 1955 25hp big twin whisper power... I need to get it running or any info I can on it... the numbers on the transom are 25018-12515... I would like a part number for the knob on the transom clamp that's kinda rectangular. .. also I hear troubleing things about the crankshaft seal?... I'm good on the ignition stuff... but what's the oil I need for the lower unit? Thanks

 

[F_R]

Yep, serial numbers -09501 and up have the troublesome seal, which includes your 12515. Be sure to check/replace it. Part number 303804, replaced by 321467.

Do you mean the clampscrew handle? Part number 375747, replaced by 388347, replaced by 433675. Use regular 80-90 weight outboard gear oil.

 

[Bigtwin55]

Oil capacity? And what exactly in short will need to be done to replace the seal... I'm no mechanic for the love of it just the necessity of it... also it has sat for several years I'm sure I can get it running as I usually think if it has a spark and a roughly tuned decently cleaned carb it will run even if poorly for a minute till I can dial it in... what other gaskets or seals should I look into doing? And the water pump should be delt with to yes? Hopefully I can get it to last another 50 some years... Thanks

 

[F_R]

You have to remove the powerhead to replace the seal. It really isn't as hard to do as it seems. You will need a new powerhead gasket when you put it back together. The old seal isn't too terribly difficult to pry out.

Yes, a new water pump impeller for sure. Be sure to install a new o-ring in the groove at the top end of the drive shaft.

Have you looked at the ignition yet? It has cracked coils unless they already have been replaced. Get new ones here at iboats.

It takes about 14 oz of gear oil. Figure on spilling a bit. The drain plug is on the bottom of the nose cone. DO NOT remove the Phillips head screw.

 

[Bigtwin55]

Yeah they are cracked... I said I wasn't worried about the ignition bc I'm fairly familiar with the points systems because of a old goldwing lol.. and doesent sound like two difficult of a job if its only a 2 part change out job I.e. the seal and powerhead gasket... I've got the pn# for the seal but do you have the pn# for the powerhead gasket and the pn# for the coils? Also I want a manual but I can't seem to find a usable copy anywhere... am I missing something?

 

[F_R]

Powerhead gasket is 303974, replaced by 304545. Coil is 580118 replaced by 584477 (18-5181 here at iboats).
There are some good and some not-so-good videos on You Tube. Look for some by cajuncookone for ignition repair. That ignition system is the OMC Universal Magneto, used on virtually all single and twin cylinder models from mid 1950's to 1973, and even beyond on some models.

 

[Bigtwin55]

Also I'd like the pn# for spark plug wires and lower unit seal kit and impeller kit... and I'm missin the handle for the pull rope I could put on a generic one but in trying to stay as colse to original as possible is there a pn# for that?

 

[HighTrim]

You need 7mm metallic core plug wire. I would get 5 to 6 feet for sure.

I sent you a PM regarding this.

 

[Bigtwin55]

Ok thanks... still need all those part numbers though if you see this f_r.... thanks

 

[F_R]

1. Dealers buy the wire in 100 ft rolls and cut off what you need.
2. Rubber boots for plug wires 580339
3. Seal kit 18-2686 (iboats)
4. impeller (only) 775521 or 18-3006 at iboats
5. Original starter handle 277294---obsolete

 

[Bigtwin55]

Hey f.r.... the o ring you mentioned in the water pump part... it comes in the pump w/ impeller kit?

 

[HighTrim]

No but it should come in the gearcase seal kit.

 

[Bigtwin55]

Last question... what's the best option for a manual w pn# ... I hear picking up one for the johnson 25 rd series motors is more in depth and cheaper... also I don't need any spring or special washer for the crankshaft swap? Just the new carbon ring and a powergasket? Thanks... nothing but good things I have to say of this forum and the people... super helpfull

 

[HighTrim]

I sent you my email. I was going to send you the parts manual so you could look up any number; but did not hear from you.

 

[Bigtwin55]

Can't seem to figure out how to reply back it takes me to a string of post u have wrote on when I click on the message.... still waiting to hear from ya f.r

 

[F_R]

Last question... what's the best option for a manual w pn# ... I hear picking up one for the johnson 25 rd series motors is more in depth and cheaper... also I don't need any spring or special washer for the crankshaft swap? Just the new carbon ring and a powergasket? Thanks... nothing but good things I have to say of this forum and the people... super helpfull

You won't be swapping anything. Just change the seal. It is not carbon, just an ordinary lip-type oil seal. Now if you are real brave you could change the whole thing to revert back to the design before the "improvement" was made. But you have to tear it down and replace the lower main bearing to do that. Um, did I suggest just change the seal?

EDIT: Although your motor is not directly represented, there is a lot of good stuff here at this Viking website. Look at the 22D and 25D models. They are very similar to your 25hp except for cowling and yearly changes. http://www.richardlpaquette.ca/vikingmanuals.htm

 

[Bigtwin55]

And 80w-90 correct... I have a outboard gear oil pump I get to use for the first time lucky me lol... in one day pretty much I've gotten all of my questions answered... awesome