Super C Distributor/Ignition

[TNSuperC]

I mentioned in another post that my SC would cut out a bit sometimes idling and under a load...pulling my 2-12" moldboard plow. Another symptom was the SC exhaust was very sooty. It spat black specks all over the hood especially when I first cranked it. The Zenith up-draft carburetor has only one tuning screw. I monkeyed with that a bit with no success. I surmised that the timing was off and that it wasn't efficiently burning the fuel. The problem I had was that at some point in this tractor's lifetime, the TDC "pointer" had been removed. I could see the marks on the crankshaft fanbelt pully but there was no reference marker on the frame of the tractor. I was told that this "pionter" consisted of a bracket that was bolted to the front of the block near the hydraulic pump. I finally asked a retired IH mechanic to take a look at it. He noted that my distributor had some "play" in the shaft which was typical. In order to compensate for this, the previous owner had to open the points a good bit...in fact way outside what the service manual calls for. He also noted that inside the distributor, there was a good bit of metal shavings. He recommended that I replace the points first and see how well we could tune it. I should note that my SC has been converted from a 6V to a 12V system...and it does not have the magneto system. The distributor is purely stock (same as when it was a 6V). Here is a photo of the inside of the distributor with the shavings.


I'll update you on the outcome.

 

[Soundguy]

ifthe dizzy bushing are wore so that points gap is irregular.. it's gonna be a bear. incorrect points gap leads to lots of other issues.

those shavings will cause problems of their own.

i se ethe rubbing block and cam are desert bone dry.. they should have some cam lobe lube on them.. and I'd find out whats been rubbing the shaft where it's polished shiney..

 

[DJ54]

Could very well be, that under the breaker plate, and governor weight guard, one of the springs could be broken, on the dist. gov. weights, making the shavings. If that is all the damage that would be done, it would be a somewhat inexpensive repair. A new set of springs run about $24.00. That could very well explain some sluggish response also. I found rebuilt distributors online for $259.00 and up, with a $100.00 core charge.

As far as the timing... There should be timing marks on the flywheel. If it is halfway clean inside the clutch housing, you can see them through the hand hole in the bottom of the clutch housing. You'll need a nice bright light to see it. If the lower clutch housing cover is still there, there is a pointer on the inside of it.
When I am working on a new one ( new to me...), and need to set the timing, I normally clean this timing mark pretty well, then if my paint pen hasn't dried up, I mark it with either white, or yellow, so it's easy to find, if need be again. Unless it has already been done. Back in the day, I kept a pack of modeler's paint brushes in the tool box, for this specific reason. There was usually a can of some color around to suit my purpose.

With the flywheel timing mark dead on, I will loosen the distributor just enough, so as to rotate. Depending on how good my hearing is that day, I will either remove #1 plug, and ground it out, where I can see the spark, or just pull the #1 wire out of the cap, and listen for a snap of the spark. This all done naturally.., with the ignition switch on. Doesn't take but 30 seconds or less, if you're all ready to go. Just don't forget to shut the switch off, then snug it down.

I've attached a picture I got doing a search for the timing marks. Sorry if it is not too high of quality. My repair manual is at the other farm, and cannot scan that particular picture.

Hope this helps..!!

 

[DJ54]

Here is an exploded view of that distributor. Note part #15, which they call the cam, the rotor button attaches to. It slips down over the (#18) distributor drive shaft. And it doesn't show any bushings in the housing to be replaced.

I'm guessing the shiny spot, is just where the bottom of the rotor button has been riding.

And, yeah, I looks plenty dry. Guess they didn't know what that little red capsule (or used to be) was for.

 

[TNSuperC]

DJ54,

You are dead on the money! I took the distributor out and tinkered with it most of the morning. Yes, one of the spings had come off (looks like many years ago) and was totally demolished. All the metal flakes came from the under-side of the breaker plate where the mangled sping had no where to go. The "play" we saw in the cam shaft was "rotational play" due to the lack of spring tension on the weight arms. I am very surprised at how well this tractor ran with this major failure in the distributor.

No wonder the tractor ran so inconsistently!

I scored a used distributor from a bone yard up the road for $50. The housing is not as good as mine, but is in good condition for a 60 year-old part, and good enough to run :thumbsup:. I'll give it a try tomorrow.

Yeah, as far as the timing mark through the hand hole, I'll take a look again tomorrow.

 

[Soundguy]

yep.. that 'play' rotation is your advance.

looks like a cheap fix, and it will take load better now!

DO clean and lube the rubbing block.

ml1 is the lube from napa if your points didn't come with a capsule of it.

 

[DJ54]

As Grandpa' used to say... "A blind hog finds an acorn every now and then...." LOL... Glad that is all is was, and got you a reasonable fix.. Your're going to love that lil' tractor..!!

 

[TNSuperC]

I don't have the SC back running yet. I believe it is due to my inability to set the time. As mentioned earlier, the bracket, on the front of the engine, that has the timing mark on it, is no longer there. I was able to find the timing mark on the fly-wheel. Someone had already smeared white paint over the marks so they were visible. So now I've lined er up on TDC and adjusted the distributor cap to align to the rotor button.

The problem I ran into was the rotor button still has rotational play...I'd say about 5 to 10 degrees. Upon further inspection I noticed the flat side (up in the rotor button) was worn on one of the corners. This was allowing the button play. I'm on my way today to get a new button and cap...might as well. I'll let you know if I can get this thing started again.

I'll also post some photos of my original distributor which may be of interest to some.

 

[Soundguy]

i've used masking tape as a way to make a loose rotor button stay put and snug. if you don't find a new one.. try that. past that you will get some shaft rotational play from the advance..e tc..

 

[TNSuperC]

I knew I had the timing set pretty much spot on, but I couldn't get the SC started. I resorted to pulling each plug and cleaning with a brass wire brush. After reinstalling the clean plugs, she fired right up and ran smoothly for a bit but then started cutting out again. All plugs were sooty and dry. So I still have either an issue with the points or carb. She's running too rich. I still plan to check the compression, but since the plugs were dry, I'm thinking that is not my problem. I suppose it is possible that the carbon in the chambers is residual and may burn off over time. I noticed that after a bit of cranking, the zenith carb leaked pretty badly. Looks like the fuel is overflowing out into the short intake hose that is connected to the oil-bath air filter. I'm no carb expert, but from what I've read this seems to be a float issue. Looks like I'll be tearing into the zenith soon.

 

[DJ54]

It does sound like a float issue. May be stuck, need readjusted, or, they can even get a pinhole in the solder joint, causing them to sink. If and when you tear it apart, shake the float and check for gas inside.

You may get by with just tapping the side of the bowl and jarring it loose, but then it may be doing it again pretty quick. Not saying there may be speck of something holding the needle valve open.

When you tear it down, be sure to remove the el, where the fuel line attaches. There is supposed to be a filter screen attached to that el. If it is damaged, or gone, it may be letting specks of rust, or dirt into the carb. causing float/needle valve problems.

 

[TNSuperC]

BTW, my carb is a zenith 11188 (or 355486R91). I see more SCs with Carter carbs. Is the zenith a decent carb?

 

[DJ54]

Both of mine have the Zenith. I put a Borg-Warner carb kit in one 15 years ago, or so, and the other one has not been touched, that I know of.

0 problems....

 

[Soundguy]

deffinately sounding like carb issues to me.

ps.. brass brush is not the best way to clean plugs. it can leave metalic streaks ont he insulator that conducts, thus causing poor spark, and fouling. an abrasive air cleaner is good.. then blow out and a shot of brake cleaner.. etc.. then gap.. etc.

also check for intake gasket and carb gasket leaks.. the vacume leaks lean out the system, making you enrich the carb too much to compensate.

I knew I had the timing set pretty much spot on, but I couldn't get the SC started. I resorted to pulling each plug and cleaning with a brass wire brush. After reinstalling the clean plugs, she fired right up and ran smoothly for a bit but then started cutting out again. All plugs were sooty and dry. So I still have either an issue with the points or carb. She's running too rich. I still plan to check the compression, but since the plugs were dry, I'm thinking that is not my problem. I suppose it is possible that the carbon in the chambers is residual and may burn off over time. I noticed that after a bit of cranking, the zenith carb leaked pretty badly. Looks like the fuel is overflowing out into the short intake hose that is connected to the oil-bath air filter. I'm no carb expert, but from what I've read this seems to be a float issue. Looks like I'll be tearing into the zenith soon.

 

[TNSuperC]

I got the zenith off this morning and proceeded to tear it down. The carb was very clean. I knew the previous owner said he'd recently rebuilt it. There were only three things I noticed. First, there was a small piece of crap in the "well vent jet." This was easily blown out. Second, the float was set at 1 8/32" which is 3/32" too low. The instructions that came with the carb kit said to set both float pontoons to 1 5/32" from "machined surface of the bowl cover." So I adjusted the float to the correct height. Third, I noticed the "throttle valve" didn't completely close the intake tunnel (I could see a small gap on each edge...but this could be normal).

Further, I removed the "main nozzle," "idle jet," "needle," and "needle seat" and cleaned them. They were all very clean. The float pin was clean and didn't have any flat spots on it. Not really much to it...so I can't let this dern thing beat me!

Now I'm not sure the carb was the problem, but will reinstall and give it a try.

 

[Soundguy]

anything?

 

[TNSuperC]

I finally got a little time to put the zenith back on the tractor and give it a try. I cut the fuel on and waited to see if the carb had any leaks...none. So I tried to crank it and she fired right up with a little help from the choke. I let her warm up and ran the engine a bit. Still had some stumbling at first but seemed to get smoother the more it ran. At full or even half throttle, there was no cutting out. When I'd back her off to an idle, she would spit a little. I adjusted the idle screw on the carb to see if it would help...maybe some.

I cut her off and re-started several times. She started easily each time. So, my thinking is that she may need a bit more fine tuning but seems to be running as well as I've ever seen over the past couple of years. It rained all day yesterday so I won't get a chance to put her under a load...that'll be the real test for me.

Just a couple of notes:

1. I found that cylinders 1 and 4 each had an old sparkplug washer in the head. It is dark and dirty in those recessed plug holes and I never noticed these even though I'd removed and replaced the plugs a couple of times. Maybe that'll help with power just a tad since those two plugs were not as far down in the head as they needed to be. I'd say the extra washers were about 3/64" to 1/16" thick.
2. The plugs I'm running are fairly new Champion D15Y. Don't know if this is good or bad, but I've read autolite 3116s are preferred by many over Champions.
3. I noticed when I took the carb apart that the "Main Jet/Nozzle" was tightened down all the way. When I reinstalled it, I went by the instruction sheet that came with my carb kit and backed out the "Main Jet/Nozzle" two turns from "lightly seated." My carb is a 67x7 so the "Main Jet" and "Main Nozzle" are all one piece. My carb kit covers the 61-62-67-68-161-267 series. Some of the carbs in this series have a separate "Main Nozzle" and "Main Jet." It seems many folks over the years have had issues with these carbs running rich. The instructions for reassembly do have special instructions which are somewhat confusing. Maybe folks with running rich issues neglected to back out the "Main Jet/Nozzle" the two turns.

 

[Soundguy]

if it's a fuel needle.. backing it out more will make it richer.. if it's an air circuit.. backing it out more elans it. I'm not as familiar with that carb series as some other zenith and MS carbs.

 

[TNSuperC]

Just wanted to post an additional detail on the replacement distributor. The distributor shaft has a plate mounted to it. The plate has two pins mounted on it that the spark advance weights pivot on and a hole that limits the amount of spark advance. The plate in my original distributor has "30L" stamped into it. The replacement distributor I got from the bone yard has "20L" stamped into the plate. Does anyone know what this means?