1967 evinrude ski twin oily spark plugs and low compression (90-95 psi each)

[rgnjc]

Recently acquired 1967 evinrude 33hp ski twin motor. I replaced ignition coils/condensers last week...spark test looks great and the motor runs decently although it still needs some work (which I'm eager to do). I ran half a gallon of gas with a half bottle of seafoam through the engine last week. The new plugs seem to be really oily....like thick black oil so I think it means its running lean (not sure what to do about this although I plan on cleaning the carb next).

I did a compression test today on a warmed up motor and the cylinders measured 90 and 95psi. I understand this is pretty low, and that its more important for them to be similar so I at least have that going for me. Is this typical for this motor or is it low? Not sure on the history of the motor so I don't know the internal condition. Certainly responded to a half gallon/half bottle seafoam treatment because it sounds better now. I'm thinking of doing another treatment. Should I try spraying seafoam into the cylinders and soaking them overnight? Should I clean the carb next? Not exactly sure what should be the next step to bringing this old motor back to its best condition, but I'm eager to do some work on it.

Any suggestions? Will appreciate any feedback regarding the compression and spark plugs! Thanks!

Edit: I'm running 1:50 mixture of oil:gas

 

[F_R]

I believe your compression is ok. As for spark plugs, they probably are ok also. All the gunk you cut loose with the Sea Foam is messing them up.

Are you running this thing on a boat on the lake, or in a tank? I'm guessing in a tank. Get it on the boat and go for a ride, and get the carburetor adjusted properly. After a nice fast ride, it will clean itself out. IMPOSSIBLE to do it in a tank unless you are lucky enough to have a large professional test tank and correct test prop.

Before you run it though, replace the water pump impeller (if you haven't already). After all the work you have done, it would be a shame to destroy the motor by cooking it because the old rubber impeller disintegrated.

 

[rgnjc]

OK cool, I'll look into how to adjust the carb...although I don't know how at the moment. Up till now I have left the carb alone and havent made any adjustments. I just assumed the last owner knew what he was doing (which I dont think he did because of a number of cheap DIY fixes on the motor that I've found). I'm running it in a lake/river. I already replaced the impeller and also all the o-rings in the lower unit so its good to go.

 

[rgnjc]

Took the boat on the river today. At idle speed and WOT turning the carb adjustments doesnt seem to have an effect on how the motor runs. At idle, turning the low speed knob either direction had no effect on how the motor ran, what does this mean? I thought that when you turn it down the motor should sound like its about to cut out, and then you turn the knob up a bit. Am I understanding the adjustment knobs incorrectly?

 

[F_R]

There is something wrong with that story. I may be wrong, but I suspect the knobs are way out of adjustment and you haven't gotten them even near. With motor running at wide-open throttle, turn the high speed needle in (clockwise) until it starts to falter, then back it off till it regains power. Slow down to idle and do the same with the slow speed needle. Double check by repeating.

It CANNOT continue running if you turn the knobs too far clockwise, because that cuts off the fuel supply. If it does continue to run with them screwed all the way in, there is something wrong (either they aren't really going all the way in, OR it is getting fuel from some other route. The knobs may be improperly positioned on the needle valves, limiting the amount you can screw them in. Easy enough to loosen the screw and reposition them.

EDIT: After servicing literally thousands of motors, I sort of forget that some people do not know the very elementary stuff. Like a couple of tricks of the trade. Loosen the screw and pull the knob off the slow speed needle, flip it over and reinstall it (wrong side out). Now you can turn the needle full 360 degrees. Screw it in all the way (gently), then back it out 1-1/2 turns. Disconnect the link from the high speed needle, then turn it and screw it all the way in an back off 3/4 turn. NOW you are ready for a test run and final adjustments as explained above.

It will be running too rich with those presets. At full throttle, it will be doing what we call "four-cycling", though it really isn't. As you lean it out, it will smooth out and take off like a bat out of hades. Leaning it even more will make it falter or even quit. Find the sweet spot. Then same thing for the slow speed one at idle, except now when it is too lean it will probably sneeze or stall.

When you are satisfied, put the knobs back on properly, pointing straight up.

Running too rich is causing the oily mess you are complaining about.

 

[rgnjc]

Awesome thanks for this explanation, its exactly what I was looking for! I'll do what you suggest this weekend and see what happens. This motor is new to me so I don't know the history of it, the previous owner may not have seated the needles correctly and they are just way too loose. I kind of suspected the needles weren't installed correctly when I turned both knobs and neither had an effect on the motors performance. Perhaps I should pull them out to see what the condition of the needles are.

 

[Robert Ellis]

Should I clean the carb next? Not exactly sure what should be the next step to bringing this old motor back to its best condition, but I'm eager to do some work on it.

Hi, I'm currently running a couple of these motors and quite like them. If it were me, I'd hold off on cleaning the carbs until I was sure it was needed. As I understand it, They need to be disassembled for cleaning ... you can't simply dump carb cleaner in them because of the varnished float. I would however clean the filter in the pump and the gas lines. I like to put it a disposable in-line fuel filter before the pump and then never have to worry about the pump filter (and gasket) again. Depending on the condition of the gas lines, you might consider replacing them.

You didn't mention the gear oil. If you haven't changed it - change it (make sure both screws have the plastic washer). If you have changed it, drain it and see if it's picked up any water - it's easy to pump back in if it looks good. Don't touch that Phillips head screw though! lol.

 

[Tim Frank]

I just assumed the last owner knew what he was doing

That assumption has cost a lot of people a lot of money....

 

[rgnjc]

Hi, I'm currently running a couple of these motors and quite like them. If it were me, I'd hold off on cleaning the carbs until I was sure it was needed. As I understand it, They need to be disassembled for cleaning ... you can't simply dump carb cleaner in them because of the varnished float. I would however clean the filter in the pump and the gas lines. I like to put it a disposable in-line fuel filter before the pump and then never have to worry about the pump filter (and gasket) again. Depending on the condition of the gas lines, you might consider replacing them.

You didn't mention the gear oil. If you haven't changed it - change it (make sure both screws have the plastic washer). If you have changed it, drain it and see if it's picked up any water - it's easy to pump back in if it looks good. Don't touch that Phillips head screw though! lol.

Cleaned the gas pump mesh filter the other day, had some grit and sediment on it but nothing too major. I also purchased a seal kit for the lower unit and changed the oil and all the o-rings and seals, the lower unit looks to be in great condition.

 

[HighTrim]

Im sure after following Franks advice, you will figure things out.

Something else to note. If the packing nut is too loose (7/16 nut behind needle) the bushing that the needle threads into may be free spinning. This will make you THINK you are adjusting the needle, when in fact you are not doing anything. This is usually the reason when I hear that the needle is not affecting idle. The bushing is just a smooth insert, that has internal threads for the needle to thread into. What keeps it snug in the carb body is the friction that the packing nut puts on it. So, if the packing nut is too loose, it just free spins, making any adjustments null and void. SO tighten that up, turn needles in clockwise until they seat, ensuring that you do not crank on them once tight damaging tip, then back out as Frank described, 1 1/2 for the low, and 3/4 for the high. Then fine tune on water.

Regarding decarbs, I dump 3/4 of the can into about a gallon of fuel, then put the other 1/4 can into a spray bottle. Take the motor out into middle of lake at dusk. I do this so as to no anger my neighbours or have them call 911 when my motor is smoking like a volcano! lol Run it at a high idle, while spraying the spray bottle into the carb throat. It will smoke like crazy doing this. Normal. Then bring to dock, remove plugs, and spray some more into cylinders. Then let it sit. Next day, I take it for a WOT run to clean things out. Sometimes, plugs need to be changed after doing this as they could foul from junk getting freed up from decarb.

Let us know how it goes.

 

[rgnjc]

OK so here is the update on this matter. I pulled the adjustment needles out, they looked to be in great condition so I simply cleaned them with seafoam and shot some down the holes to make sure its all nice and clear. I put them back in and took the boat on the lake today. It ran like a lawn mower at first, but after adjusting the high speed needle it took off like a bat out of hell and ran great. Then I adjusted the low speed and the boat ran so much smoother than it had in the past. I was very happy with this. Though I had to take the knobs off though to properly adjust them, both needles had to be screwed almost all the way in before the optimal position was found, and it couldn't be done without removing the knobs first. Overall, the motor ran stronger and smoother.

Sadly, I then developed a new problem. In trying to hook up some lights, some wires fried in the bundle between the motor and junction box assembly. Like sizzling and completely burnt, smoking, and super hot. Anyway the motor ran like junk after that. I wrapped them in electrical tap and limped back to the dock. Now I've got a new electrical problem to contend with. Hopefully its just a couple of fried wires. Will pull out the bundle of wires and take the wrapping off the entire thing and see what wires are fried. It may be best to just replace all of them. Since I think they're all original. I will make a new thread for this problem when I start working on it later this week, if I have questions. My new rule of the day is, don't mess with the electrical out on the water.