Farmall A engine problems (Revisited)

In Reply to: Farmall A engine problems posted by Doug Stockman on February 28, 2010 at 13:21:17:

Thanks to everyone for replying. I finally got some time freed up to try some of the suggests others made. I am happy to report that compression is good (100, 105, 105, 100) – no major rebuild needed. I did look at the spark from this cranked, magneto-started Farmall A. I do not have another magneto-fired tractor to compare. I compared the spark to my 1973 distributor fired Cub. The magneto spark is about ½ as bright as the Cub spark. If others feel this is weak, what should I replace first on the magneto to see if I can improve the spark. As mentioned previously, the plugs probably have less than 30 hrs on them. They still looked very clean. The plug wires also do not have many hours on them, well less than 500 hours I suspect. The magneto cap contacts did seem dull so I attempted to polish them up a bit (no help).

I was unable to check the intake manifold because I cannot get the tractor started again.

One concern I have is that maybe the carburator is where the problem exists. I am losing much more gas out of the bottom of the carburator than I remember happening before (when cranking). This might be due to the fact that previously the tractor started very well. However, I worry maybe I have a stuck float. I did tap multiple times on the carb but no difference. When I pulled the bolt out of the bottom of the carb, there was much gas still in the carb.

What do others think is my next best step?

Thanks again to everyone for their help. Much appreciated.

Doug
Original post

On the spark side, I'd be thinking about at least shining up the points (a folded up dollar bill works nicely for most light grime and corrosion) if not replacing them. If that doesn't do it, it could also be the condenser. Replacing the latter will require removing the mag. And as long as you're that far along, I'd remove the coil cap and coil and check out the spinning magnet in the bottom for strength. It shouldn't rip a nail right out of your hand, but it should be able to hold a 16d common nail when turned upside down. If you've taken the mag off, it's important to do things right to get it back on and timed back up poroperly. If you have manuals, the procedure for that is in both the Operator's and Service Manuals. If you don't, come on back and we can walk you through it. But start with the points, which are under the dust cover under the distributor cap and don't require removing the mag body from the tractor.

Also, if you have a set of new plugs sitting around looking fro honest work, thry them. I've had my BN decide not to start, and ahd that to work. NOthing at all unusual in appearance about the plugs that came out, but the new ones had her up and running.

On the fuel side, I'm wondering if you aren't just over-choking it. The 113/123s don't tolerate much choke before they flood. two maybe three full turns of the motor at full choke is about all they'll take. If mine hasn't started by then I'll open the choke wide for a few more turns and if more is necessary try it at about a third. It will vary with weather/temp etc, but the key is to be real sparing with the choke.

If you are going to put new points in, watch that the rotor drive gears are in time so that the rotor is "pointing at" the correct plug terminal on the dist. cap. Our A mag was out a tooth & was hard to start. Dad said that he never had the gears apart & it must have jumped a tooth sometime.

Thanks for both replies. I will try changing the points (which I have never done before, is it self evident or should I find documentation first?). I am a bit hesitant to pull out the mag, but it might get to that.

I have never needed to choke the tractor to start it except when very cold. Below about 10 degrees I would choke it and I would often only do for 1-2 pulls and then turn the choke off and crank again and it would start right up.

Thanks again.

Doug
Penfield, NY

You're welcome. Before trying to change the points, try just cleaning them first. Doesn't take but a few minutes. Pull the cap and rotor and pry up the dust cover under them. You'll se the points off to one side suaually the side toward the motor. Fold up a dollar bill spring them open, and slip the bill in between. Let them spring back closed and with the tension on them rub that bill back and forth a few times.

As far as replacement, if that's needed, again not a bad job. They come in two parts. The arm with the spring that hinges on a pivot pin and rides on the cam of the distributor shaft, and a smaller piece that screws directly to the distributor body. All you need is a screwdriver, a .013" feeler gauge, and a little wrench (I think it's 11/32"). The wrench will be used to disconnect the hot wire attached to the arm, which can then be pulled right off. (Tip: Work on a clean floor or put a drop cloth under your work area so you can retrieve the little nut that might go flying on you.) The screwdriver will remove the smaller ground contact. To install put the new ground contact in place without tightening it down. Install the arm and hook the wire back to it. Put it so that it mates up with the contact on the ground side. Use the fan to turn the motor so that the fiber/resin block under the arm is resting on a high spot on the cam ( a rounded whoulder, not the flat area). Then loosen the ground point back up, and adjust it so that the feeler gauge jst slips petween the contacts on the arm and the ground block. There's a knack to it -- there's not a lot of room in there for fingers or anything else to hold that grounding side in place, and it will tend to twist or move to open or close the gap as you tighten it down. So it may take a little fiddling and a few tries, but if, when you're done, you've got a gap of .013" and the two sides are mating together, you've got it.

Doug, my 1940 A starting troubles were primarily a flooded Carb. I think dirt from gas tank, and weak float or needle were causing issues. A new carb. fixed all. Starts on second pull always. Look east on 441, I"m out in Marion.
Tim