1955 7.5hp Evinrude

[Greg O.]

This summer I bought a 1955 7.5hp Evinrude. I have a few questions about it.

It seems to have good compression, but when I checked it I was only getting 75 to 80 psi. The engine was room temp, about 65 degrees. I had it running back in August and it seemed to run pretty good, but the carb needs cleaning. What is a typical normal compression for this engine?

Besides the normal stuff like points, pump impeller, lower oil, what other items should be looked at?

I am considering converting this outboard from the pressure tank to a pump system. Is this a good idea, or is it better to leave it stock?

Is there a forum just for old Johnson and Evinrudes?

 

[Mas]

Re: 1955 7.5hp Evinrude

The compression is a little low...but even which is good. I would do a "decarb" and your numbers should go up a little if the rings are coked up. If the pressure tank that you have is operational and not rusted out, I would keep it stock. Make sure the fuel line is in excellent condition...if any doubt...replace the fuel line...which is still available. The only "issue" with pressure tanks would be an old fuel line springs a leak and pressure from the motor fills your bilge up with gas. Just replace the line if in question.

Mas

 

[Mas]

Re: 1955 7.5hp Evinrude

And yes...AOMCI.org is the antique outboard motor club website. They a great resource for the oldies. Non-members have access to their forum and classifieds. I would encourage you to join, however, if you're into the oldies.

Welcome by the way,

Mas

 

[Greg O.]

Re: 1955 7.5hp Evinrude

Thanks for the reply. The reason I am considering converting to a pump is the tank that came with the engine is really rusty inside. So ether I find a new tank or do the conversion.

I will check out AOMCI.org. I have several Martin outboards. This is my first Evinrude. I would like to pick up an old Johnson as well. One of the red models.

Another question is paint. What type of paint works well on outboards? Are there any paint chip numbers that are close to the original?

 

[Mas]

Re: 1955 7.5hp Evinrude

Try NYMarine for paint: http://www.nymarine.ca/index.html

A rusty tank is not good...a pump conversion or reliable tank might be equal money...maybe cheaper for a reliable pressure tank.

Mas

 

[levi_tsk]

Re: 1955 7.5hp Evinrude

i just did that conversion on my 5.5 its pretty easy but youll need an intake manifold gasket, fuel fitting, and a carb gasket i used the mikuni fuel pump df44-211d i got it off ebay for 17.99 and a couple dollars shipping the most expensive part is the fuel fitting pn#0393334 dont substitute this part number for another on this motor as there isnt enough space for the threaded one and a threaded nipple and then to not kink the hose as i goes through the hole -hang on to the old fitting as someone may want it later if you sell it
nymarine sells the all the orginal colors for outboards
use 1/4" from the fitting to the pump and then 3/16" from the pump back to the carb and 1/8" vacuum line from the pump to vacuum port)
take the carb off and then the intake manifold off then youll see two little valvey things take the screws holding them in place out and save the parts in the same bag as your old fuel fitting now you have two holes in the intake, plug one with a vacuum cap put in rounded end first and cut to about 3/8" long leave the other one ALONE put everything back together making sure the vacuum cap stays in the hole run 1/8" vacuum line around to the starboard side of the motor then run the 3/16 line from the carb to the pump andthen from the pump to the fitting ill go outside and take a pic in a second and post it for you

 

[levi_tsk]

Re: 1955 7.5hp Evinrude

fuel line routing (fitting to pump)

fuel line routing (pump to carb) in the middle of the pump,pointing straight out, is the vacuum line that runs from the pump to the port that you modify with the vacuum cap

 

[Mas]

Re: 1955 7.5hp Evinrude

Any chance of getting a little more light on the pics...It's a bit too dark to see!

Mas

 

[Steve A W]

Re: 1955 7.5hp Evinrude

Here's a series of articles on older OMC motors.
http://www.duckworksmagazine.com/07/columns/max/articles.htm
I've got a 1955 5.5hp Johnson, a great motor but not big enough for My 16' jon boat.
I just picked up a 1957 18hp Johnson, Sure is gonna be a long time till spring!
Steve A W

 

[levi_tsk]

Re: 1955 7.5hp Evinrude

yeah sorry i tried to adjust the lighting and then played with the photo editing program its the lighting in my garage and the web cam on my laptop -they both suck

 

[F_R]

Re: 1955 7.5hp Evinrude

Vacuum line is a poor choice. With a few possible exceptions, that stuff can't stand gasoline. And don't even think there is no gas in that pulse line. Use fuel hose.

 

[Greg O.]

Re: 1955 7.5hp Evinrude

Thanks everyone for all the imput. I am looking forward to getting this little jem going. When I was a kid I would go to a youth camp and they had old Johnsons and Evinrudes this vintage, so this is a re visit to my childhood.

 

[jmendoza]

Re: 1955 7.5hp Evinrude

Great little engine. Remember, it's 25:1 on the oil. It does pay to remove the welch plug and clean the low speed orfices, I had to on mine. I replaced the float with a new foam one as well. We aslo opted to do the Mikuni square diaphragm pump mod. But if you have some citric acid (powdered) you can boil out the tank with it, mix it with scalding hot water and soak the tank, I use one cup per gallon. Reheat the as needed acid for faster cleaning, then flush it real good w/ cold water, rinse with denatured alcohol to absorb the water, then swish some gas and oil (4:1) in there to coat it and protect it from rust. There are line and tank rebuild kits availlable on line. Here is my CD-11 after restoration:

 

[cajuncook1]

Re: 1955 7.5hp Evinrude

I have 7.5hp Evinrude and I have her running pretty good. I had to change all the ignition, carb kit and had to change the pinion shaft and shock absorber.

Oh, by the way per the service manual 1955 7.5 Evinrude/Johnson use a 16:1 gas to oil mix ratio.

Good luck