1973 6hp running on one cylinder

[BigB9000]

I have been working on this 6hp for awhile.

I rebuilt the carb,
resealed the lower unit
new evinrude water pump kit
new fuel pump
new lower crankcase O-ring and gasket
2 new plugs
2 new coils
and 2 new breakers/condensers.
even compression at 80psi in both holes.

I test started it today (bucket) the RPMs are fine in idle, but in gear quiet sluggish. about 1/2 the RPM's.

while idling, I pulled the top spark plug wire, and no change to idle.
Replaced top plug wire, and removed bottom plug wire. and engine dies.

I figured it was a spark issue, so i was fiddling with the wires, and noticed a small hole in the plug wire for the top cylinder. and noticed it arking against the engine block. So I know I have a leaking plug wire.

Pulled plugs, bottom is wet looking while top is dry.

Reinstalled plugs, started, and played with the top plug wire some more. no change in performance. Still sluggish in gear.

removed plugs again, top now wet.

So, my questions are. Could the leaking plug wire cause it to not fire the top plug correctly?

Maybe the top cylinder isn't getting gas somehow?
or maybe some other type of fuel delivery problem?

I have never used a outboard this small before, only 115hp. while test starting it in water will it be sluggish in the bucket, but fine on the lake?
(also, my bucket is actually a 50 gallon drum, filled a little more than half way with water)

could prolonged use on only one cylinder cause major engine failure?

 

[DJ]

Re: 1973 6hp running on one cylinder

Spark is going to take the path of least resistance. The spark plug is not it if it has another path.

That little engine is just like a 115, just in miniature.

You only have one carb. so fuel is going to get to both cylinders.

Replace the plug wires.

 

[jay_merrill]

Re: 1973 6hp running on one cylinder

It sounds like you just need to put new plug wires on it. You have replaced everything else in the ignition system, so I would do it, regardess of ignition leakage issues.

I would also spend 5 bucks on a spark checker. You can get one at any auto parts store.

One other issue with the older, points equipped outboards that I have run across - especially with my Johnson 6hp motors, is that the point gap must be set precisely. Get the gap set off of the mark or just not at the correct gap in general, and you can have problems. I've had these motors not spark and then run fine, once the gap was readjusted.



???

 

[BigB9000]

Re: 1973 6hp running on one cylinder

Changed the top wire and plug connector.
I would have done both, but I only had 1 extra (new) connector.

Tested it with the spark-test light. The bottom cylinder still has a MUCH stronger spark.

Maybe set the point gaps?
how do I do that?

-update-

I read through my manual (factory, which isnt that great) and it says at full throttle, the points should open here:

Well it doesn't, it doesn't open till here:

And the top cylinder is so far off it isn't even funny.
it doesnt open till here:

the T timing mark is being pointed out by the screwdriver.

So, thoughts?

Video of it running:
http://www.youtube.com/watch?v=lR3D_Jm0G9M

is this even possible?

Also, the manual says to adjust gaps,check gaps, etc etc, but never actually tells you HOW to adjust the gap. So, how is it done?

 

[jay_merrill]

Re: 1973 6hp running on one cylinder

Don't worry about the external timing marks - if you set the point gap properly, it will automatically be timed correctly.

Pull the flywheel again (you are using a proper, harmonic type puller, aren't you? ) Look down at the top of the crankshaft from above. You will see a "sleeve" of a larger diameter, at its base. It will be uneven in "roundness" - this is your cam.

As you look at it, you will see a small triangular "arrow," with the word "Top" printed between it and the crankshaft. Where that arrow is located, is the high point of the cam. Rotate the crankshaft by putting the flywheel nut back on it and using a breaker bar/socket to move the crank in a clockwise direction, looking down.

Keep rotating, until the arrow is perfectly lined up with the rub block on the point arm for one cylinder. This is the high point on your cam. Make sure that the armature plate is in the idle position, when you do this.

Set the points for whichever cylinder you are working on to .020. Some people like to set them at .018, but I prefer the OMC recommended .020. In order to do this, loosen the panhead screw that holds the point base down, just enough to allow you to move it with a screw driver and the slot that is cut into the base. There is also a cam shaped screw that sticks up through the base, that has to be loose enough to move. Once you get the gap set and the panhead screw retightened, check the gap again - it is very easy to have the base plate move, as you tighten the screw. Do not overtightened the screws! Your are turning a stainless steel screw into an aluminum part and if you "crank down" on it too much, you will strip the threads in the aluminum!

Repeat this process for the other cylinder, by rotating the crankshaft such that the high point in the cam is positioned for it. Make your adjustment and retighten. Double check you gap again.

While you're "in there," double check your coils, to make sure that they are exactly even with the bases that they sit on. If they are off center (twisted a little), they will drag on the flywheel, as it rotates. Obviously, this is not a good thing.

I wrote all of this by memory and I get a little fuzzy on this stuff, when I haven't done it in awhile. That being the case, I'm not going to get offended, if anyone corrects me on any little goofs that I might have made.

Once you get all of this done and have the spark plug wires replaced, you should be in good shape!

BTW, are you going to need some help on the wire replacement (you will have to remove the armature plate to do it)? If so, let us know and we'll walk you through it.



???

 

[Tom @ Buzzard Bluff]

Re: 1973 6hp running on one cylinder

Jay wrote:
<While you're "in there," double check your coils, to make sure that they are exactly even with the bases that they sit on. If they are off center (twisted a little), they will drag on the flywheel, as it rotates. Obviously, this is not a good thing.>

Not correcting you Jay---just trying to clarify a bit for one unschooled in old OMC magnetos.

The coils sit on cast-in 'towers' or high points on the magneto base plate. The upper and outer edges of those 'towers' are machined to a specific circumference. There is sufficient 'slop' in the screw holes through the coil shoes to be able to align them flush with the machined surface on the 'towers'. When that is done properly then the shoes and the magnets in the flywheel are spaced correctly to achieve the best spark the system can generate.

 

[oldcatamount]

Re: 1973 6hp running on one cylinder

You fellas are giving us all some very good advice! Having a '67 6hp Evinrude myself, I have been there, done that, and find your descriptions are very good. This site is helpful. I log on almost everyday and each time I do I learn more and save a bunch of money and reduce my aggravation. We appreciate your generousity!

 

[BigB9000]

Re: 1973 6hp running on one cylinder

...

pssshhhtttt! Thats it?

Wow that is easy.

turns out the gap was set at about .0015 and the point was bent. Probably from someone torquing down the condenser screw too much.

I'm kinda surprised it even sparked at at.

Well, back to the test bucket.

 

[BigB9000]

Re: 1973 6hp running on one cylinder

Still not right. or is it?

here it is at full throttle:

http://www.youtube.com/watch?v=HO6LYTCESKk

here it is without the top plug wire plugged in:

http://www.youtube.com/watch?v=Huxz7IDRK8A

opinions?

or is that just the way these little 6's run?

 

[jay_merrill]

Re: 1973 6hp running on one cylinder

Its pretty hard to tell anything by running the motor in a small barrell. I would use a spark checker on it, to see the quality of the spark that you are getting on each coil/wire.

Also, did you ever change the wires?



???

 

[BigB9000]

Re: 1973 6hp running on one cylinder

Its pretty hard to tell anything by running the motor in a small barrell. I would use a spark checker on it, to see the quality of the spark that you are getting on each coil/wire.

Also, did you ever change the wires?



???

I did use a spark checker, and I only changed the top wire. I ran out of new parts. I'll have to wait until they come in before I do the bottom.

 

[BigB9000]

Re: 1973 6hp running on one cylinder

Its pretty hard to tell anything by running the motor in a small barrell.

...thats a 55 gallon drum.

Should I get something bigger?