Super C Distributor/Ignition

[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?