TOPIC: Compression specs ?

I have just gotten back to work on the pair of 1959 Johnson 35hp that were froze.After using a mixture of mystery oil/acetone for a few days it finally broke free. I cannot find any specs on what to expect on compression. These engines came with the McChesney and were only used from 1959-62 when the boat was stored so they have low hours but were not properly stored. I get a reading of 90psi with 3 bumps on the gauge. I do plan to remove the head to inspect the cylinders and install new impellers before testing them.I hope to be able to get this boat wet this coming season.

Also, this boat had an motor board attached to the transom that extended out to 12". What are the advantages of this set up. Thanks

Melanie

Melanie,
I would guess the motor board was to account for the motors. Are they long shafts? If so the board was probably to bring them up higher to compensate vise getting short shaft motors. This is a guess of course, I'm no expert.

The motors I think should have in the low 100's on compression but they will run just fine at 90. plus they will probably be a little higher once they run and get warmed up. My 59" Rude Fat Fifty is 90 across the board and runs just fine. Probably just rebuild the carbs, fuel pump, maybe the thermostat and you should be good to go. You may want to check the crank shaft seals also.

Bob

Evinrude and Johnson did not give any spec as any of us in the AOMCI have been able to find for the 50s and early 60s motors. However with may of a big twins under my belt around 130 is good. You may get the motors started, with 90, however run the oil a bit heavy and the rings may work loose or reset. That motor runs not on a 50 to 1 mix, however a 16 to 1 (1/2 pt to a Gal)

The motors for a long shaft and a short shaft had no differences to them beside the shaft

Here is a site for the parts manual for that motor...however they are a bit high on parts

I have a few parts motors laying around if anything is needed and I still have it

www.marineengine.com/parts/vintage-evinrude-johnson/ITEM_2977/catalog.html?http://www.marineengine.com/parts/vintage-evinrude-johnson/ITEM_2977/ITEM_297700001.htm

Allan

Hi, Melanie. As stated, the transom extension was probably to allow a long shaft motor to be used, sometimes twins. If left off, a big short shaft motor was used. An unknown (back then) benefit was moving the gearcases away from the boat into cleaner, less aerated water for better efficiency. Many modern bass boats and other hot outboards have notched transoms and/or setback brackets to accomplish similar goals for faster running. Gives the prop(s) a better "bite" of water to push with. So, its a win/win.

Oil mix on a '59 Johnson 35 need not be 16:1 and is actually recommended to be at 24:1 (quart to 6 gallons).

Also, the OP said the motors were "froze". Why were they frozen? I recommend a complete teardown of any motor that has been stuck due to the likelihood that there are now rust marks on the bearings which can kill the motor in short order. Pulling the cylinder head isn't going to tell you what the crankshaft journals look like...

Good call Scott. Totally read over the frozen part, sorry.

Bob

Thanks guys for all the responses. I believe the motors are short shafts,17-1/2" from the bottom of the transom clamp to the cavitation plate. Is this correct? Since the transom on the boat is also 17-1/2" the use of the remote motor board may be as Kerry mentioned, "Gives the prop(s) a better "bite" of water to push with. So, its a win/win." , since the boat was ordered with it.

The history on the boat and motors is that the owner took possession of the boat June 1959 and used it during summer vacations in '59,'60,'61 but then married and the wife was not into boating so the the boat went into dry storage for 42 yrs. The motors appear to have been in dry storage all their lives but I realize without proper maintenance during storage that rust/pitting would occur so it looks like I get to tear down my first outboard,oh joy. Luckily when I purchased the motors I ordered complete gasket sets along with new impellers but they didn't come with crank seals.I have fuel pump and carb kits on their way and will start my search for bearings/seals.Again thanks for the input and I'd appreciate any tips or words of wisdom before I tear into this project.

Tore down engine #1 today. Crank shaft journals/bearings are in great shape with no pitting or any roughness but may need to replace due to rust where a retaining clip at the rear of the crank used to be. The drive shaft stayed with the power head so it looks like I will need to tear into the lower unit as well according to everything I've read. Anyone have a good crank for 1959 RDS 21B Johnson PN #306252.

Scott-
Same oil mix for the '51 thru '55 Big Twin 25's?