1970 Johnson 20 hp throttle Q's

[Wolf86]

Hello,

I've got a couple of questions about 20RL70. They are best explained by a picture; unfortunately I don't have access to the exact engine but I've found a picture of an identical engine.



Q1: Should the roller move all the way up to the slide on the plate? It only moves up to the vertical markings.
Q2: The throttle piece on the carb moves only by a tiny bit. Am I guessing right that wide open throttle should rotate by like over 90 degrees?
Q3: What are these vertical markings for? My first thought is that they indicate full throttle or something.



Q4: The spring (piece no 100 on the picture) in the throttle lever seems to push the lever gears away from each other. But it pushes them too far away so the gears never mesh. It seems to me a spring should instead push them towards each other. Without the spring, the gears mesh very well but occasionally slip out since the lever can move inwards/outwards by a bit.

I hope there is someone who can be of any help. Any help, even little, is appreciated. Thanks.

 

[HighTrim]

Re: 1970 Johnson 20 hp throttle Q's

Is there a problem that you are trying to troubleshoot, or simply looking for the workings of the motor?

If you are in neutral, you are limited to the travel.

The 2 vertical markings are for setting the points timing. They are used when setting the points in conjunction with a timing fixture/analog meter. 1 set of points will open when the timing fixture is between the 2 marks, then exactly 180 degrees later the second set of points will open. This is by far superior to setting them with a feeler gauge. Setting them to open at exactly the right moment, as well as 180 degrees apart, is important.

Using a feeler gauge gets you kinda close to that, but not exactly.

 

[F_R]

Re: 1970 Johnson 20 hp throttle Q's

The spring pushes the cone shaped piece #101 into a matching taper inside the twist grip. That provides friction that helps prevent the grip from turning if you turn loose from it (at most speeds). Yes, that also moves the whole thing, grip shaft and gear outward. However, it was designed that way on purpose and is NOT why your gears are not meshing. So, look for something else. How about the flange on the bushing #106?

 

[Wolf86]

Re: 1970 Johnson 20 hp throttle Q's

F_R, thanks, I'll look into it.

HighTrim: thanks. I had problems with stalling.

So do I understand correctly, that it's not supposed to travel too far in neutral for safety reasons? And it's supposed to travel all the way to and up the "slide" on the plate when in gear and WOT, also pushing the lever on the carb all the way to the stop?

I had the engine react with delay to increase in throttle a couple of times. It also did not really like idling, it seemed like it needed just a bit more gas not to stall.

One other thing, possibly contributing to it, can be a dirty carb, although the previous owner sweared he had thoroughly cleaned it. But the engine ran well for a couple of hours and I think at some point something in the throttle got worn out and mispositioned.

 

[Wolf86]

Re: 1970 Johnson 20 hp throttle Q's

Is this picture correct?

 

[AlTn]

Re: 1970 Johnson 20 hp throttle Q's

the carb linkage roller should be between those 2 marks just as the throttle plate begins to move < you can observe the roll pin that holds the throttle plate shaft to see this movement >.. in forward the carb roller should move to the highest point on that timing plate and the throttle plate should be perfectly horizontal in the carb throat..this is maximun timing advance and maximum throttle..at idle, the carb linkage roller may not be in contact with the timing plate...idle stop is adjusted on the port side just below the vertical shaft <you'll see a longish screw there that limits the movement of the vertical shaft >...find an idle speed after the motor is hot, adjust that screw and the idle mixture needle to get the smoothest idle...lot of wind that a 15 second video would show you...

 

[Wolf86]

Re: 1970 Johnson 20 hp throttle Q's

Thanks! I'll try that!

 

[Wolf86]

Re: 1970 Johnson 20 hp throttle Q's

Did some tests and alignments to the throttle linkage.
At idle the roller goes up to between two marks. (And yes - half the distance it is not in contact with the plate and, well, doesn't roll. Then it starts rolling until the area between two marks)
In forward or reverse it goes further until the highest point on the timing plate and carb throat thing is horizontal. When there, can't go to neutral until the plate is back between two marks.
Seems to be correct?

Compression is 70 psi in both cylinders with no difference whatsoever. Heard no difference is more important than low numbers, not sure, cus ideal should be 14.7 * 6 = 88.2 psi.
Sparks ok.
I will try to start it in spring after thaw.

Edit: There are little discoloration spots under the cover and some paint flaked off on the leg. I know little about painting, should I just buy an outboard paint and go over it?

 

[kfa4303]

Re: 1970 Johnson 20 hp throttle Q's

Sounds like you got it all put back together Wolf. I have a'66 20 hp I can take pics of if you need any for reference. Throttle should be linimted when in idle to prevent over revving and a "runaway" condition. 70psi is a bit low, but not bad. Like you said it's more important that they be well balanced. In fact you might actually see the compression numbers improve once the motor is up and running and had a chance to get warm. Run a 24:1 mix ( aprox 6ox TCW-3 oil to 1 gal. 89 octane gas) with Champion J6C spark plugs and you'll be good to go. I love my little '66 20 hp. Very strong, reliable and light weight. Holler if you have any more questions.

 

[Wolf86]

Re: 1970 Johnson 20 hp throttle Q's

Wow, man, thanks! Do you have some painting/touch-up recommendations?
(Specifically, some discoloration on the block and some paint flake off on lower leg exposing bare metal, fortunately it has not yet begun to rust. The paint is dark green and probably original)

 

[Wolf86]

Re: 1970 Johnson 20 hp throttle Q's

(ping)

 

[kfa4303]

Re: 1970 Johnson 20 hp throttle Q's

Hi wolf. I'm not much of a painter, but I can tell you the basics. The discoloration on the power head is probably mostly on the head gasket and due to an overheat at some point in the motors history. It's fairly common. You can either buy a new head gasket that that's the same color as the current head and just swap them out, or you can go all out and paint the power head you have. They do make factory reproduction color paints and decals available at Nymarine.com, if you want to go all out, but lots of folks have had luck with brands available at most stores, like Rustoleum and Duplicolor. All surfaces you want to paint should be very clean and free of grease and oil. A 50/50 mix of white vinegar and water works well. Acetone also works well. Once it's clean you want to do a light sanding with 220-320 grit paper and wipe down again. You can now apply a light layer of Self-etching aluminum primer, especially to any bare metal areas. You should be able to get it at most auto parts/home stores. One can should be plenty for a whole motor. After a coat or two of primer, you can apply the paint. After the paint is dry that's really about it. Most folks don't put a clear coat on any parts that go in the water on a regular basis as it tends to flake off, but a couple coats of clear on the cowl couldn't hurt. These links will help too. Keep us posted. We love pics.

http://forums.iboats.com/showthread.php?t=237937&highlight=painting+outboard

 

[Wolf86]

Re: 1970 Johnson 20 hp throttle Q's

Thank you, will try that! We tried the motor last year (when it worked well) on a really old 5 m/16 ft rescue inflatable. Probably can call it RIB since it has this thick heavy wooden floor. Got it really cheap, maybe will restore. We got 9 knots fully loaded, 14.5 knots when alone. Since then we've made the motor ride higher, it was way too underwater.
There's a video, it only shows coming back to port.
http://www.youtube.com/watch?v=-EzvwdTM8B4&feature=share

 

[kfa4303]

Re: 1970 Johnson 20 hp throttle Q's

Hello again Wolf. I would think that your motor should push you along a bit more quickly. Try raising the motor as you said until the cavitation plate, found directly above the propeller, is level or even 1"-2" higher than the keel of the boat. My 1966 20 hp pushes my 14' aluminum boat at about 20-25 mph, so I would think that you should get close to that. Of course, every boat is different and you'll have to experiment with til/trim and weight distribution to find just the right balance for your needs. Check the forums here for more threads on painting. There are some really good restoration jobs that have been done by members.

 

[Wolf86]

Re: 1970 Johnson 20 hp throttle Q's

I've removed the prop, the nut was quite rusty so I broke the cotter pin, but the shaft looks clean and good. The prop has a somewhat rough edge and a single chipped part, 1/5th of an inch perhaps. There's a part inside that seems to be stuck but overall I think the prop is worth restoring.

Now for the visual inspection, carburetor looks good and the gasket doesn't look worn at all. It seems it had been serviced just before I got the motor.

Powerhead, however, is kinda locally rusty - on the bottom and near the thermostat cover. But especially on the bottom of the lower cylinder near one nut. The head gasket seal looks worn from the outside. Might be hard to pull off, not sure, gonna try when it gets a little more comfortable outside and in the garage. (I'll also make the pics of any work I'm doing)

Changing the gears feels smooth, flywheel and pistons move smoothly and make a sucking sound (hmm, is it good?). I added just a tad of two stroke oil in the cylinders in the fall and turned the engine over a couple of times. To be frank, I knew little about winterizing motors back then, but I figured two stroke oil goes in there anyway so it's better than nothing. I've been turning the engine over once a month or so. Also, in the fall, I used up a can of WD40 on outside parts in hopes of preventing further rust.

Ordered a new Sierra water pump impeller and lower unit washers. And since they didn't have Champion J6C, I got alternative NGK B6S which should be the equivalent according to the charts.

Def needs repaint since I see small exposed metal areas on many parts of the leg. It's all clean though, no marine growth or such.

It's tempting to inspect the coils - although it has spark in both cylinders, I don't know when they have been serviced last. I don't have a harmonic puller for the flywheel, though.

 

[kfa4303]

Re: 1970 Johnson 20 hp throttle Q's

Hello again Wolf. No worries. Cotter pins break all the time. It should be easy enough to find another one. I'm glad the carb looks ok too. However, if you need a carb kit you can get one right here at iboats for about $20 US (not sure about shipping to Estonia through). As for the power head, the discoloration, peeled paint and rusted lower bolt, make it sound like the motor has, or used to have, a blown head gasket which allowed water intothe cylinders. As you've noticed, the bolts on the powerhead can and do rust. As a result, they can be hard to remove at times. In fact, it's not uncommon for them to brake while trying to remove them. However, using a good penetrating oil and a bit of heat from a torch can help get them out. You didn't hurt the motor any by putting in the 2 stroke oil/WD-40, and turning it over periodically is also good an prevents binding. I would really try to find some Champion plugs as that is what the motors where designed to used and the conversion between brands is not always very accurate. Again, you can order them from here if need be. I would also suggest you take a look at the coils and ignition. You will learn a lot, and making sure everything is working properly will give you piece of mind when you're on the water. If you can't find a harmonic balancer puller, do a search here in the forums for "homemade flywheel puller" and you'll find all sorts of clever solutions members have come up with using various bits of scrap and their ingenuity. Here are some links that can walk you through an entire ignition rebuild should you need it.

http://www.outboard-boat-motor-repa...on 3 HP 1952-1967 Ignition System Tune-up.htm

http://www.duckworksmagazine.com/03/r/columns/max/07/index.htm

http://www.duckworksmagazine.com/07/columns/max/index1.htm

 

[Wolf86]

Re: 1970 Johnson 20 hp throttle Q's

Thanks. The impeller and other things have arrived but they'll have to wait a bit. Got a new trailer last month since we were renting last summer and blew a hole in the inflatable using a trailer with no rollers, while trying to get the boat off.
Before getting that motor I was looking into buying a 33 hp Johnson from the 60s. The owner was quite passive so I went for this one.
Now it's up again with owner claiming ignition has been rebuilt. I've heard 33's are nice but I'll stick with this one of course and try to make it work properly.

 

[kfa4303]

Re: 1970 Johnson 20 hp throttle Q's

Hello again Wolf. I used to have a 1966 33 hp. They were basically a budget version of the 35 hp. It was a good motor and uses the same ignition system as all OMC motors from that era.

 

[Wolf86]

Re: 1970 Johnson 20 hp throttle Q's

Hello. I have a picture of the prop. I sent the pic to a repair shop with questions but they wouldn't answer. Gotta keep looking. It's a 9x9.

 

[Wolf86]

Re: 1970 Johnson 20 hp throttle Q's

Hello. I have a picture of the prop. I sent the pic to a repair shop with questions but they wouldn't answer. Gotta keep looking. It's a 9x9.
View attachment 132271

I'll take the motor to a warm place next week for repairs so I'll post the pics then. I think I'm going to pull the head off and inspect the cylinder walls and the pistons first. I wonder whether replacing the head gasket and probably sanding the head a little would raise the compression by good amounts? Could it jump to 100 psi? This doesn't seem particularly hard to me. I have blowout diagrams for this motor which have helped me a lot. Messing with the pistons and rings is to me somewhat new and thus 'hard category' DIY work.