how do I tune old Johnson TD20

[dancamp009]

Hi, I need to know how to set the points and timing on my old Johnson TD20 5 hp outboard. It is year 1945-49. It uses the older type coil system different from any of the others. It has two sets of points which I think I've adjusted okay to .020 (though I'm not sure I did it correctly), and now I need to set the timing. Not idea how to do that.
Also, before I took the top off I tested the spark and didn't noticed very little, if any, spark coming to the spark plug. Is there a way to check the coils on this too?
Any help would be appreciated.
thanks

 

[OBJ]

Re: how do I tune old Johnson TD20

Welcome to iboats Dan!

What's the coils look like under the flywheel Dan? Any cracks in the coil covering? If you see any, make sure the coil isn't going to ground. You can see this as it will make a black mark under the coil. If the coil is cracked up pretty good, replace them.

When you set the points, did you make sure the point wiper was on high cam? .020 is the correct setting.

There is no timing to set on these engines. However, what you want to check is the cam and carberator cam follower are in sync. The cam sets under the flywheel and the carb follower rides on the cam. There should be a reference mark on the cam. When this mark is centered on the follower, the throttle plate should just start to move in the open direction.

Do you know the last time the carb was cleaned and rebuilt? If not, it would likely be a good idea to consider this.

Have you considered getting compression readings? These come in handy and are good for future reference.

If you have just aquired the engine, an impeller change out would really be a neat idea as well as a lower unit gear lube change out.

These old engines will run like tops with a little care maint. They will start easy and give a lot of trouble free use. But...you gotta' take care of her.

 

[dancamp009]

Re: how do I tune old Johnson TD20

Thanyou Fleet Admiral for your prompt and very helpful response.
The coils themselves look like new, no cracks anyplace or dark marks from grounding.
I did find two reference marks on the cam. One is the word "top" and opposite that (on the other side) is an encircled letter "V". Which one would be the reference mark?
The throttle plate opens depending on where the throttle handle position is in reference to "Fast, Start, Slow, Stop" possitions. At which position should the throttle plate begin to open? It's hard to see with the carb dangling where the throttle should be but perhaps I can figure that out with more investigation.
I did clean out the carborator just lately and it looked pretty good inside.
I also didn't see any spark jumping to the plugs when my friend pulled on the engine. Could old condensors cause low spark or would that only be from the coils? How can I test those condensers? If they are bad, can I bring them into a car parts supply and have them replace them or do I need special ordered ones?
I tested the compression with my finger and the bottom cylinder seems very week. The top one seems fine. Should I squirt some oil inside the cylinder in hopes of freeing up a frozen ring?
If I ever get this baby running, I will check out the impeller too.
Thank you again for all your help and any more you can muster.
much appreciated

 

[F_R]

Re: how do I tune old Johnson TD20

The TD coils are almost bulletproof. Condensers have every right to be leaky, considering their age, but often will work anyway. By far, the biggest troublemaker is the points. They gotta be clean! Best to take them apart and clean each contact individually till it's shiny bright. But a word of warning, there are a bunch of little insulators in those things, so watch how they go and don't lose anything. Set them to open .020 at their widest gap.

Back to the condenser question, whatever you can fit in there will work as long as the capacity is somewhere near correct. I would have to look up the specs, but they probably are around 0.2 to 0.3 mfd as a guess.

 

[OBJ]

Re: how do I tune old Johnson TD20

Compression is ALL important to an outboard. If you can borrow a compression testor (gage), make sure you have compression on each cylinder. The readings on each cylinder should be 10>15% of each other. If one is very low, you may consider scraping the engine or like a lot of us.......rebuild....but do be aware that the mechanical parts like rings are not a common thing these days. In fact, I would check the compression on each hole before going any further. If they are close, do a decarb and then recheck. May just be some sticky rings.

When setting the points, put the point wiper on the "TOP", stamped into the cam.

If you are in doubt about the condensers, replace them. Any J/Rude dealer should have them in stock.

The spark to each cylinder should jump a 3/8" gap easily. Quick way to find out, take a ten penny nail and cut the head off. Shove the end of the nail into the spark plug lead and hold the pointed end about 3/8" away from a clean engine ground. Have a helper pull the rope. If you get spark across the gap, you should be OK.

Don't hesitate to post any other questions you may have about the engine.

 

[F_R]

Re: how do I tune old Johnson TD20

OK, I just looked them up. The condenser part number is 300153 and they are no longer available. But my guess was right on, the capacity is 0.2mfd.

I believe there is some confusion here. The TD does not use the Universal Magneto as on newer motors, does not have a separate breaker cam (it's ground on the shaft), and has a rod linkage between the mag plate and carb.

But I 100% agree, check the compression before you beat yourself to death on this thing. Those are good running motors if in good shape, poor if not.

 

[OBJ]

Re: how do I tune old Johnson TD20

Yep....didn't check on the condenser availability from BRP. Thanks for getting my confusion factor squared away FR......d.......I keep thinking 50's/60's.

If you think you can get the old girl running and do want the correct condensers (and points) you might try TwinCity Outboard or SeaWay Marine. Both have web sites.

EDIT: FR....since you know your older engines real good.....are the points in the engine (in this thread) the "conventional" type or are they the ones with the little "push rod" in them that work off the cam?

 

[F_R]

Re: how do I tune old Johnson TD20

They have the push rod.

 

[OBJ]

Re: how do I tune old Johnson TD20

FR....if you wouldn't mind, I may have some questions for you on a 2.5....46'>50'. I'll collect what I want to ask and get with you.

 

[dancamp009]

Re: how do I tune old Johnson TD20

Thank you all this time. I'm amazed at the response here.
Yes, you are right this is the older type magneto and does not use the Universal Magneto as on newer motors, this is why I had to come here for help. I could only find one push rod coming from one of the set of points. I guess the other isn't suppose to have one. They both are built slightly different too, which I'm sure is correct.
Tomarrow I will test the compression with a tester and if it is extraordinarily low in one cylinder (like I'm expecting), then I will pop off the cover and clean it out (I take it this is what you meant by "decarb") and see if it made any difference.
If not, I guess I should give up on this one.
Once again, I sure do appreciate all your help on this matter and I'll be sure to let you know how this goes since you guys actually appear to be genuinely interested or at least very helpful.
thanks again
Dan

 

[F_R]

Re: how do I tune old Johnson TD20

No, they both need the push rod in order to function. True, they made a small change or two in construction through the years, but all work the same way. Unless you have something really wierd there.

 

[Scaaty]

Re: how do I tune old Johnson TD20

Make darn sure those coils are good...notorious for cracking. And if they are the brown ones, probably junk even if they look good. 20 bucks any good Johnny dealer. Email me at dub, dub, dubYa dot hogrider@myway.com . points in the subject line..I have some points and condensers. Used, but came from motors with bad coil. Robby

 

[Chinewalker]

Re: how do I tune old Johnson TD20

Scaaty - Actually, the TD and TN series coils are quite sturdy and not nearly as prone to cracking as the Universal mag style.

Dan - I would do as FR suggested and clean the points spotless. Both sets need their plunger - each set fires it's cylinder independently. The condensers are usually good, too, but it wouldn't hurt to have them tested. Any small engine shop should be able to do that for you if you don't have the means yourself. I have some parts mags kicking around if you end up needing something...
- Scott

 

[F_R]

Re: how do I tune old Johnson TD20

For you youngsters out there, this is the mag we are talking about here

and

 

[dancamp009]

Re: how do I tune old Johnson TD20

Wooo, let me say "Thank you Master Chief Petty Officer". I just came back online to find the spark plug gap size (.030) and low and behold found more than I bargained for. I printed your piece up and will hold on to it for just incase it doesn't start again and I have to take it apart once more. After cleaning the points and putting it all back together, I got electricuted while trying to ground the spark plug wire holding on to a shirt and turning over the cam with a wrench, so I guess I got spark afterall. I just got it all back together though before viewing your post so I'll have to wait till next time to tune it up right. Before I can test start this baby I have to let my bucket of water thaw out, it's like 20 degrees here today and I'll have to wait for that to thaw before the big test.
I'll be getting back on this though. thanks again for the file. much appreciated.
Dan Dan, the bus man.

 

[dancamp009]

Re: how do I tune old Johnson TD20

I got it to where it will crank but can't get it to keep running. The bottom cylinder keeps fowling the sparkplug. so I'm taking Fleet Admiral's advise a little late and doing a compression test as soon as I rustle up a reasonably priced compression tester. Will report results. By the way. How much work is it to pull the piston on these oldies? And are rings even available for this old TD-20?

 

[Scaaty]

Re: how do I tune old Johnson TD20

OK, OK, OK...(on the old style coils).Brain shook back into place (been working too many later style old motors lately...2 QD's and a FD) l have a set of the old style coils here. Kinda forgot on the switch to the brown coils that fell to pieces if ya looked at them crooked. Yep on the push rod points too...think I have a set here too! (I GOTTA spring clean around here!)

 

[dancamp009]

Re: how do I tune old Johnson TD20

I checked the compression, gave 50 LBS in each cylinder, put plugs back in after cleaning them with starter fluid, the motor ran great after three pulls for 10 seconds then died. Couldn't get it to run again or even putter. Not sure now what to do next. I've cleaned the carb, but didn't soak parts (they looked clean), cleaned and set points (maybe I'll try that again too if nothing else works). I've got a feeling it's not getting enough gas or the gas is bad (it's a couple months old at least). Does anybody know what to turn that little screw by the carburator to? I'm not even sure what the little tiny screw is (behind carb) but I turned it all the way in then out 1 1/2 turns. How can I test to see if it's getting enough gas? It doesn't seem to fouling the plugs afterall. I'm excited now though, at least I know it can run and it does have even compression.
thanks again
DanCamp009

 

[Scaaty]

Re: how do I tune old Johnson TD20

Take out the gas tank petcock and clean it and all related up to the carb first..

 

[Chinewalker]

Re: how do I tune old Johnson TD20

Hi Dan,
Sounds like you're making progress!
There are two needle valves on this motor. One for idle, one for anything above an idle. The idle needle is the one that runs at an angle from the center main bearing area on the crankcase - the one with a bend in the shaft for a handle. Turn that one to about 1.5 turns out.
The other needle valve is the one that runs up through the tank. That one should be at about 1.5 to 2 turns out. You'll find the sweet spot once you get it running. It is also the primer - press it down and you should hear a good squirting sound. Don't do it too much or you'll flood it.
As Scaaty was alluding to, check your fuel flow. You can remove one of the lower brass screws from the carb to confirm that fuel is getting to and passing through the carb bowl. It is possible that your float and needle are sticking. Those old cork floats can be distorted and hang up in the bowl. Was it well sealed and in good shape?
Once you do get it running, do a decarb (lots of posts on that here on the boards) as you might be able to bring up the compression numbers a bit. These older motors with their rich oil mixtures can build up a lot of carbon on the pistons and in the exhaust passages. Often a manual removal of carbon is necessary, but try the liquid decarbs first.
Having fun yet!
- Scott