1959 Evinrude 3hp Lightwin

Hello, I am repairing an nice 59 Evinrude 3hp. My dad had it and had complained of low power-not revving up fully. He bought it from a roadside sale. I know it was just a poorly tuned carb, but it had too many tell tale signs of it being tinkered with. I decided to pull it down to just the short block for now as $150.00 for gaskets and rings is cheap insurance.
A few questions.
1) What is a good compression number? I got 60 psi on each, forgot to oil the cylinder to do a wet test, but there is a good oil film in each bore. I know the gauge is good because I get 120 psi out of my 9.9 hp.
2) Does everyone still run the 24:1 mix with this engine? My friend has a 68 Johnson 3 hp and by all looks of it it is the same basic engine and it calls for 50:1. Tuned right it shouldn't smoke much, but just curious.
3) Lastly, I want to double check the orientation of the pistons, as this engine has been opened up in the past. They look correct from memory and double checking off my 6 hp & 9.9 Johnson's. Squared side of the dome towards the exhaust, and the smoother taper towards the intake transfer ports correct? Only reason I ask is because my 1960's Neptune 500 has the piston the opposite. Squared side of the dome towards the intake transfer ports. Guessing this was a mistake on Neptune's part? I installed that piston per the owners guide that came with it.
Thanks again for the help.
Brian

P.S. Also, I noticed that the intake port is really tiny compared to the carb bore. Guessing this was done to make it a "3 hp"? Has anyone port matched this before? I will leave this alone as it is my Dad's and is really nice engine. But if was mine I would port match, and watch to avoid over revving it.

Squared side to intake.--This forces the incoming charge up to scavenge exhaust out the sloped side !!-----Sloped side to the exhaust..-------Once again I say that gas / oil mix was a " board room " decision.-----The general public believes that a 50:1 motor must be better built then a 24:1 motor.----They also went to 100:1 for a few years.----Yes I say that oil / gas mix is a much mis-understood concept.----You need to verify piston installation in your 6 HP and 9.9 HP motors too.

Racerone, Thank you for the reply so quick. Ok, so my Neptune (top picture silver engine) is put together correct then right? So how about the bottom blue engine, the 3hp? Exhaust would be on the left where you can see my glove. Pistons look to be in 180 deg off then by my reckoning? I will have to borrow a bore scope to look in my 6 hp & 9.9 hp again as was hard to see in the spark plug hole. Don't really want to yank the heads yet, that will be a winter project as they both are being used, and the 9.9 still has factory sealed paint around the engine, so I am guessing that one is alright. As to the fuel mix I have read so much info. But I have run 2 strokes on anything from 120:1 Amsoil to 20:1 Non-detergent #30 motor oil, all ran great, but the carbs were properly tuned. Was just curious about this as it is a 100% bushing engine with no needle bearings. I will just have him follow the 24:1 mix and keep it tuned proper and run a set of J6C or B6S plugs in there as this is his puddle jumper trolling motor.
Thanks again for the replies, many answers helps to make an informed decision

Wrong....wow! How did that happen? Flip pistons 180. I run all my bushing motors at 50:1 and even 64:1 on trollers. Amsoil Saber extremely great lubricant.....non oxy fuel only. Been using 100:1 Amsoil for over 40 years in hundreds and hundreds of motors. Never burnt up a single motor. My advice......I "walk the talk". Too much oil causes carbon deposits and pollutes. We don't want 'em to shut down our 2 strokes like they did in California. Amsoil Injector is a cheaper oil....really by their own class, a 50:1. Auto injection users should not use 100:1 Amsoil.

Pistons absolutely are backwards in the 3hp twin. Connecting rods may be upside down also.

Alright, so I went out to check the con rods and they could be in 180 out from original. But hard to tell unless there is a mark somewhere on them as the main journal end split is perpendicular to the length of the rod. Well good, one issue is solved anyways. Will be ordering gaskets, carb kit, reeds, rings and a few other headache preventive's tonight as long as as I see they are available still. Thanks again, I will post some pic's and a video once it is complete.

Some rods have an oil hole that is supposed to be "up".

fdrgator said:

Some rods have an oil hole that is supposed to be "up".

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Went out to check the con rods out. They look the same top and bottom. But good tip, will keep that in mind for the future. Just made a order of essentials, this baby should keep humming for a good many years

Good evening to all. Well good news, the 3hp Lightwin is purring again on the water. Took a bit to get things working, but it is going. About 1/2 - 3/4 turn out on both high and low speed jets. Plugs are a nice golden tan, even at the factory 24:1 mix of XD30 oil and 91 non oxy fuel. Might try a tank of 50:1 next time I am out to see if the top end improves. Seems like it is right at the 4000 - 4500 range with my 12 ft Lund fishing boat and two people. It idles nice but every now and then it will sputter and open it up to clear it out, then all is well. GPS says 4-5 MPH, which seems right for that motor. It seems to be a thirsty little thing, about 5-6 MPG, but I guess it is also 61 year old tech too. Ohh well, nice motor. Thanks again for the help on getting it back running.

I always thought 1.5 turns out was the starting point for the needle valves. Seems pretty far off to me.

Swarlos said:

I always thought 1.5 turns out was the starting point for the needle valves. Seems pretty far off to me.

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Yea I thought that as well. But the plugs show good color, and it is running in it's sweet spot, turn till runs highest rpm. Give a bit more till stumbles, the back off a bit till it is nice and smooth. I dunno, i did have a issue with the cork packing fall apart around the needles, had to put the old ones back in. Will see if my local has new ones, of perhaps an o-ring might be in order.

Well, took the 3hp out once last time before it heads back to my folks. I ran it this time at 32:1 instead of 20:1. Ran very nice at that mix. Changed the off brand champ J8C to a Autolite 303. Switched to Havoline 2 Stroke TCW-3 since that is what it wiill live with the rest of it's life. Actually ran very cool compared to the 20:1 XD30.