super super fc-c timing

ok fellas

you'll be glad to hear i've got the old timer started! and i pretty much know where everything is and how it works - how'as about that??

anyway, she does start, but runs unevenly. i've checked most things, but not the timing - how do i check it or set it up??

and, i have stripped and cleaned the carb, but what should be the position of the mixture screw?

thanks again
lachleaves

For the mixture, describing the adjustments will depend on whether you have a gas or a dual-fuel carb. Assuming it's gas, there shoul dbe only two adjustments, idle mixture and idle speed. Idle mixture is a knurled screw with a spring under the head, and probably near the neck of the upper part of the carb where it goes up to the manifold, pointed slightly downwards. Rule of thumb is to have the tractor warmed up and running at idle. Shut it down, turn this screw all the way in (DON'T force it hard into the bottom of the thread!) then back it out 1-1/2 turns as a starting point, and restart the tractor (no choke necessary at this point!). Adjustments from there are pretty much by ear and from experience, to get it to a nice rolling idle (more on which in a mo). If you feel your ear or experience are lacking, one tip would be that you shouldn't have any black smoke at idel, and a minimum of black smoke, if any at all, when you throttle it up quickly from idle. Black smoke would be an indication of idling too rich. If your carb is like most (ba no means all) of them here, you would thread the screw in by quarter turns to eliminate the smokeing condition.

Idle speed adjustment (which is unrelated to the mixture adjustment) is made at the linkage from the governor to the throttle plate, usually located in a very inconvenient spot between the throart of the carb and the crankcase. On mine, with a Zenith carb, it requires a VERY long screwdriver passed from the rear through on eof the openings in the bracket mounting the air cleaner to even get to it. No real easy rule of thumb on a starting point as with the mixture screw. The best advice I can give in a nutshell is to turn the screw until the motor wants to die from starvation, then undo a little bit.

It will take some fiddling, but there is a balance to be found between the idle speed and the idle mixture that will give you a nice idle.

The mixture at high idle and under load is determined by the condition and cleanliness of the small orifices in the carb body.

Short version, low idle speed and mixture are governed by two screws on the carb. High idle speed is controlled by the governor, and the high idle/load mixture is a function of having a clean carb.

thanks scotty

my carbs the same as yours (zenith) and it is a gas engine (not duel fuel).

any ideas about the timing on the ditributor though??

If the fuel were old, the tank may contain some gel, water, or trash (rust). It was always my experience that the tractors with these gravity fuel systems will run rough until the fuel tank, fuel line and carb. is flushed out, that is after they have set up for a while. Before you start doing too many adjustments, I would first drain and clean the fuel bowl and drain the carburator and blow out the fuel line. I have seen the time when the carburator bowl had to be drained several times to clear out all the water condensate, crud and trash.

I thought about it, but think you're likely best to leave it be for the moment. If it was "running when parked" and running well enough for now, timing is not one of those things that slips out of adjustment. New points can change it by a few degrees, but rarely radically enough to affect good/acceptable running, and the fine tuning to overcome that is usually done by ear. For that reason only, I'd suggest you see how you make out with the idle adjustments on the carb first and, in the absence of a problem, wait until you can get your hands on a manual before tackling the timing.

That said, you can't get into too much trouble by checking your static (motor stopped) timing. To do that . . .

Pull your #1 plug (the one nearest the front) out and remove the coil wire from the center of your distributor.

If you have the hand crank, turn your motor (Hint: it will turn easier if you remove all four plugs) until you feel the piston forcing the air out through the #1 plug hole. Continue turning until the air stops pushing out and starts to pull a suction. From there, you have two choices for finding top dead center. You can tip a narrow screwdriver or a stiff wire into the plug hole so that it rests on top of the piston. Turn the engine fan back and forth until you find the point that the screwdriver handle or wire drops to its lowest point (meaning that the piston is nerest the top of its stroke) and stops before changing directions. That will be TDC.

(If you don't have a hand crank, I'd highly recommend removing all four plugs and using the fan to trun the motor for this part of the exercise. Trying to get to TDC by bumping the starter can lead to confusion if the motor rebounds/recoils -- i.e., it could bounce back on the compression stroke, which feels to the finger in the plug hole just like advancing to the firing stroke, at which point you may be lost. Having all the plugs out and turning by hand (fan or crank) eliminates that confusion.)

The alternative is to look up through the hole at the very front of the bottom of the front end of tje torque tube, just behind the motor. From there you can see the rim of the flywheel. TDC is marked by a line stamped on the flywheel. It runs from front to back and is marked TC, 1-4. It can be hard to see, as it's a pretty shallow stamping and is rather commonly filled up or obscured by the kind of dust and accretions that tend to gather down there. If you can find it, you'll need to turn the motor (again the fan is a good way to do this as long as the fan belt is reasonably tight) until that line is at the very bottom of the flywheel and lines up with a post cast into the cover jsut in front of it.

However you get to TDC, I'm going to assume from this point that you have a battery ignition and not a magneto. Get a test light, one that looks like a screwdriver handle with a light bulb inside, a sharp probe for a tip, and a wire (that will have an alligator clip on the end of it) out the end of the handle.

Locate the small wire that runs from your coil to the distributor, then look for the wire just opposite that on the top/end of the coil. Hook the clip on your test light to a good ground. (Test your light and your ground by hooking your clip to what you think is a good ground and touch the probe to the hot side of your battery. If it doesn't illuminate your test light, you're either on the wrong side of the battery or you don't have a good ground. That or the battery is dead.) Turn your ignition on (DON'T start the tractor!) and touch your probe to the terminal on the switch side of the coil. It will either light up your tester or it won't. That doesn't matter at this point.

With the motor at TDC on compression on #1, it's at the point where the motor should fire from a stop. The coil delivers its spark when the points open (which is another discussion) so you want to be at a point that the light is just flickering between on and off when touched to the low voltage terminal on the coil.

The adjustment (depending on what you have for a distributor) is obtained by loosening the adjusting bolts and turning the base that the cap is attached to. These are NOT the same bolts that attach the whole distributor to the motor.

If you view the entire distributor assembly as an hourglass with the cap at the top, the bolts I am referring to will have their heads at the top of the bottom half of the hourglass, fairly near to the neck, and may or may not pass through an oddly shaped flat clamp as they thread toward the motor. Don't take them out, just loosen them so that the caps of the bolts are a little away from the surface. Doing so will allow you to turn the top of the hourglass (cap and all). It may take a little gumption to get it started, but try not to move it too far in getting it loose.

With your test light making the connection, rotate the distributor cap back and forth slightly until you find the point where the test light flickers on and off. Tighten the bolts, if there are two of them, back down as evenly as possible. Even if there is only one, the aim is to keep your distributor right at the point where the light could flicker on or off. That's the point where it fires and that should be at TDC when starting from a stop. If you have to err a litle in one direction, better to have the light flicker on, so that you will be firing just slightly after TDC instead of before when starting.

Good chance I've missed something, but that's about all there is to static timing, but it should have you running, and should be good aross the whole range of speed on a new motor or a good rebuild.

Apart from that, you may discover (down the road) that an adjustment to timing might be good, and that would likely result from wear/lash in the timing gear train. That is the kind of thing that is usually adjusted with the motor running and takes an ear and some experience to dial in. It's not hard to get carried away with it and time it to a point that it runs well but is too fr advanced to strt reliably . . .

So I'll close with apologies for my length, and a redundant caution that you may not want to get into adjusting your timing until you are sure it's necessary.

Excellent advice!

It was only last summer that I first put a wrench on a large green tractor as a favor to a neighbor. I went into it with a little trepidation, but was surprised to find a Delco ignition and a lot of other stuff that was actually familiar. Got a lot of good help and advice over on the Deere board and went into it. Learned a lot in the process, set it back up by the book and still had problems. My clue when I still had problems was the unmistakable smell of mothballs. OLD GAS! Cleaned out the sediment bowl and screen, drained the old gas and replaced with fresh, and the old girl ran like a top.

ScottyHOMEy: Good tips. I'm building the engine on my Super C now and will be setting the timing shortly. The last time I static timed with a light was 30 years ago on a VW Bug. This refreshes my memory.

great advice folks.

i'll try the static timing procedure, but can i just describe the symptoms one more time...

the engine is a devil to start (crank only at the mo - since the starter motor is inoperable!) - have tried various positions of throttle (though i've only tried the choke once or twice since this seems to flood the carb something chronic!). she fires, say 4 times for approx. 40 - 50 cranks - stalling each time, until she'll just about tick over. open and close the throttle and she'll rev slowly, but open the choke and she stalls instantly. no clouds of smoke or excess petrol from the carb or exhaust at this stage(as i've had before) - but 'hunting'as though there's too much fuel coming through and generally running unevely - though not with enough regularity for me to say that one or more of the cylinders aren't firing.

i've cleaned out the fuel, the carb, the air filter and replaced the spark plugs. apparently, the previous owner had just replaced the points - hence i thought, the only thing left to check is the timing.

what do you think??

lachleaves

Ooookay!

Just to be sure we're clear on terms. An open choke is when the rod is all the way forward, meaning the choke plate is not impeding airflow. If the motor runs but dies when you open the choke, that would suggest that you either have 1) not enough fuel flow (I know it doesn't seem possible with your flooding issue, but it is) or 2) a vacuum leak above the carb.

As for fuel flow, loosen the line where it connects to the carb. Open the valve in the sediment bowl and you should have a steady stream of fuel running. If that's okay, remove (carefully) the brass elbow that the fuel line was connected to at the carb. The part you are threading out should have a fine mesh screen in it. Make sure that this screen is clean. Use compressed air, backflush, whatever seems best to clean it out.

For the vacuum leak, it will typically occur at either the joint between the carb and the manifold, or between the manifold and the head. Did you use a new gasket and snug it down well when you put the carb back on? Was all of the old gasket removed from the underside/manifold side of the joint? If you can get it running at all, one way to check for a vacuum leak is to start the motor and spray someting that will burn, like carburetor cleaner around the manifold at the places I described. If the motor should speed up or even out when you do this, you have a leak at the spot you were spraying at the time.

You mentioned hunting. Did you re-synchronize your governor to the carb after you put it back on? Find the rod that runs from the throttle arm on the carb to the governor arm. Where it joins to the governor arm, there is a clevis secured by a pin. The clevis adjusts the length of the rod by threading it on and off. With the motor off, pull the pin out of the clevis (which may take some fiddlin' in any event as they wear some and tend to rust in place, and don't forget the cotter pin or bent nail that holds the pin in place!). With your throttle lever back at the seat thrown all the way forward, pull the governor arm all the way to the rear, while also pushing the rod to the carb all the way to the rear. Adjust the clevis by threading it on or off so that the pin fits back into place with both the arm and the rod held to the rear. (It will help to clean up the threads with brushes or solvents first.) This is something that needs to be checked anytime either the carb or the governor have been off.

The last thing on the fuel side would be to re-check the adjustment of the float and to make sure that the needle and set are clean and unobstructed.

Over on the spark side, you may have new points but I wouldn't trust that they were adjusted properly or that they're clean. As Hugh pointed out, you may have a distributor of some sort that we don't know all that well. If it's an IH or Delco unit, your point gap should be .020". Shine them up with a folded up piece of whatever currency spends where you are. The joke here is that a five-dollar bill is more effective for this than a single. Don't know why it is, but currency paper and ink are pretty good for the purpose. Absent that, a couple of quick swipes with some 440 or finer grit sandpaper will also do the trick.

There may still be gremlins like a bad coil or condensor (or even the timing), but try this stuff out first and let us know how you make out.

sorry, my mistake. what i mean was 'pull the choke cable' (choke on) and she stalls instantly.

i'm sure it's too much fuel.

lachleaves

Yep!

Not sure if you have the same motor on the French version, but the 113/123 used in the Cs and SuperCs here don't require or tolerate much choke at all if they're otherwise running well. I don't give either of mine more than a crank or two at full choke, then open the choke to start it. Once running, neither of them will tolerte any choke at all.