Best years for OMC 10 horse?

[shoestringmariner]

I’m now on the search for a 1950’s 10 horse OMC. I think I prefer the Johnsons for esthetics, but I’m also considering a 57 Evinrude. I have a 58 Sportwin parts motor, but if I’m not mistaken the lower unit was actually weaker that year?

Anyway, I’m just wondering what seems to be the preference with the OMC fans when it comes to dead simple, rocksolid and easy to maintain motors? Is there a period of years where everything mechanical is interchangeable between makes? Or do shared parts only pertain to the powerhead?

[chris-p]

If you are going with a 50s Johnson, and you like the metal cowl, I would stick with a ’55 to ’58.

Yes in ’58 they switched to the 4 bolt gearcase. It is quicker than the ’55 to ’57 models. Weaker? Im not totally convinced that there is an actual problem there. Ive run/owned a ton of ’58s, with never a worry. Weaker yes, but not something to worry about anyways. The ’55 to ’57 is essentially the same motor, so just pick a cosmetic example that appeals to you.

[Steve D]

I agree with Chris, those are my personal favorites too. Easy to work on, dependable, great classic styling, durable. The ’58 and up version might be faster with a lighter load but I like the power the earlier gear cases seem to have when you have 2 guys, a full tank of gas, and all your gear on a 14 foot boat.
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[fleetwin]

Tough question for sure, let’s assume for this discussion that you have no personal preferences for brand or paint scheme.
The 55-57 models have the larger/more durable/easier to find parts for gearcase. They say the small gearcase is faster, maybe, but is that really worth the reliability difference? The main thing that killed the smaller gearcases was water intrusion, which caused the lower housing bushing and driveshaft to wear. I agree with Chris, the smaller gearcase can be reliable, provided oil level and condition are monitored frequently.
The other issue on these engines is wrist pin wear. There were no actual wrist pin bearings on these 50s models, so extended high speed/lean oil mixtures will cause wrist pin/piston and rod bore wear. This problem was solved in late 1960 models with a larger diameter wrist pin and caged needle bearings. But, it sounds like you want to stick with 50s models. Mumbles has found that the 59 models had beefier wrist pin bushings, and I really like the 59 Johnson styling and graphics, the Evinrude bread box models are unappealing. The 59 models also had a thermostat, a plus for extended trolling. 1960 models introduced fuel pumps and got rid of the pressure tanks.
So, not really able to give an actual recommendation, just pointed out some differences. I like your idea of a 57 Evinrude or Johnson model, just be sure to check carefully for wrist pin slop.

[westwind]

Did 58 not have some improvements to the powerhead? Don’t remember the details, and then into the early 60’s as well. I really like the 58 Johnson styling, here’s mine on my Alumacraft FL. Got about 20 MPH out of it, which I thing is pretty decent.

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[fleetwin]

I don’t recall any powerhead changes/improvements for 58. The flywheel was a little smaller/lighter to get the RPMs up a bit though…
I love the 58s as well.

[frankr]

The larger wrist pins with "real" bearings came out in 1961. Last year for the 10 was 1963. So there ya go–3 years to pick from if you want the good wrist pin design. HOWEVER, the improved parts can be retrofitted into the older models. You have to change pistons, circlips, wrist pins, wrist pin bearings, and connecting rods. Do that on one with the big pre-’58 gearcase and have one tough motor.

[Anonymous]

I remember a member (fleetwin?) saying the drive shafts for the 1958+ models were hard to find!

The shaft on my early 1960 QD is missing a chip on at the slot for the pinion drive key, one reason I don’t run it often, or hard.

I think a late 1960 change was a splined pinion, and heavier teeth on the gears…..

[fleetwin]

Yes, there was a change to the driveshaft and pinion right around 1960. The earlier models had pinions that were keyed to the driveshaft, later models had a splined connection. Both style driveshafts are hard to find, and used ones are usually worn in the area I mentioned.
Both style driveshafts were usually ruined by lack of oil/water intrustion causing the lower pinion bushing and driveshaft mating surfaces to get worn excessively.

[shoestringmariner]

Thanks guys. The newer Motors might have full roller bearings, but I just love the 50s style Motors.

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