Farmall A, Round 3

My '47 A, which has always been a good runner, isn't anymore.

It has a skip/hard starting issue. You can read about what I did last fall here:

http://forums.yesterdaystractors.com/viewtopic.php?t=957796

Since it's spring time I'm going to take another whack at it. The plan is to take my running '45 BN and start moving parts from one to another.

The first thing I'll probably swap over is the distributor. I'll have to rig up something to get power to it but that's easy enough.

If that doesn't do it then I'll move the manifold.

Beyond that, I'll be lost. Maybe pull the head and start looking for issue inside.

Anything else I should look at or words of encouragement?

K

(quoted from post at 08:49:14 05/01/13) My '47 A, which has always been a good runner, isn't anymore.

It has a skip/hard starting issue. You can read about what I did last fall here:

http://forums.yesterdaystractors.com/viewtopic.php?t=957796

Since it's spring time I'm going to take another whack at it. The plan is to take my running '45 BN and start moving parts from one to another.

The first thing I'll probably swap over is the distributor. I'll have to rig up something to get power to it but that's easy enough.

If that doesn't do it then I'll move the manifold.

Beyond that, I'll be lost. Maybe pull the head and start looking for issue inside.

Anything else I should look at or words of encouragement?

K

Click to expand...

Why don't you try adding an external coil. Those mag coils often do weird stuff even though they seem okay.

You need to maka a mark where #1 tower is on the body of the mag. Then remove the cap and check that the rotor stops and clicks on impulse at that mark. If the rotor is off just one tooth they will start hard. I would check that first assuming you do have good fire at the plug. Then the idle circut in the carb mite be plugged also making it hard to start. When everything is good they will fire on the first turn. Plugged aircleaner is another thing to check remove the bottom and check the cup mite be full of junk.

DO NOT move parts trouble shoot the problem could well be simple and if you move parts then the problem may not be found and more problems added to it.
#1 check spark at All 4 plug wires. It need to be a blue/white and jump a 1/4 inch gap or more. If you have that then move to the carb
Make sure you have a good steady flow of gas out of the carb drain plug. Let it flow a few minutes and catch the gas to look for water/dirt etc. If you have then then check your air cleaner.
O have fixed more engine just by doing the simple trouble shooting and many times a simple cleaning of the points or servicing the air clean and it is back up and running

Thanks for the ideas guys but if you look at the thread I linked to you will see I tired almost everything you've listed.

Now the coil on the mag, might be the case, still probably easiest to test by just swapping the distributor over.

I've tried 3 carbs, 2 of which were rebuilt, one professionally.

I've tried different wires and different plugs.

Gene, do you mean off a tooth in the mag or the engine's timing is off? I do get good blue spark. This thing used to start pretty easily hand cranking, now it's nearly impossible.

I've run it with out air cleaner, propane checked the manifold. I'm thinking it's either ignition or some sort of internal manifold issue.

Thanks,

K

Mark four locations with white paint or whiteout marker equally spaced at 90 degrees apart on your front pulley. The first of which being easy to see when the #1 cylinder is at TDC. these marks are not true timing marks, they are to be used for checking dwell variation. As the points open and close, the accuracy of the cam lobe and the opening of the points (distributor or mag) can make radical timing changes. Use a timing light hooked to the coil or mag coil wire not #1 plug. this will fire at every cylinder, and the marks should stay very close together when flashed. if they are even 1/4" apart from each other the ignition cam and or bearings are toast. Jim

There are gears that turn the rotor and sometimes when points are changed the cover is removed and in the process putting it back the timing of the gears turning the rotor get the rotor off some thats why you remove the cap and check where the rotor is when it fires so with the mark on the body where the wires go you can then see with the cap off if the rotor is times. Using the crank lets you see the rotor stop befor the mag trips. Being off just one tooth makes a huge difference in starting.

If you didn't mess with it between the time it was running good, and then suddenly not running good, then it is probably not off a tooth.

These things don't just spontaneously "jump time" with no apparent damage. Everything is gear driven, so the only way to be a tooth off is to take it apart and purposely move things over one tooth. Otherwise, the gear is stripped, and that would be painfully obvious.

(quoted from post at 05:02:17 05/02/13) If you didn't mess with it between the time it was running good, and then suddenly not running good, then it is probably not off a tooth.

These things don't just spontaneously "jump time" with no apparent damage. Everything is gear driven, so the only way to be a tooth off is to take it apart and purposely move things over one tooth. Otherwise, the gear is stripped, and that would be painfully obvious.

Click to expand...

That's what I was thinking as well. I started playing with igntion parts because it wasn't running right, it didn't start doing it after I replaced them.

K

Thanks for the thoughts guys, I'm making a list.

This is easily the most frustrating engine I've worked on. Nothing I do seems to make it better or effect how it's running at all. When it is running it's just feels strained at high RPMs and just runs like crap at low RPMs.

Two other things.

One is a few yeas back my father was using the A and ran into a beam with the muffler. It snapped the pipe off where it screws into the manifold. The pipe was very, very thin from years of use so it snapped easily. I just pulled the manifold off, re-tapped (more like chased) the threads and installed a new pipe. I seem to recall it ran fine after that but that the point in time I wonder if it got cracked some how. I've sprayed it down with WD-40 and tried using a propane torch and I can't get it to run any different. For what it's worth partial choke doesn't help either. Unless it's internally cracked.

Would a head gasket make it run this way? I have no prof that it's a problem, I'm getting 93 PSI +/- a pound it each hole when it's warm. Just thinking out loud.

Thanks,

K

In your thread of Oct. 2012, Rustyfarmall suggested it might be an internal leak of the manifold. Such a leak cannot be detected by using the propane torch and it will not affect compression readings.
I tested my manifold by laying it on its side and the 6 ports, with which it connects to the cylinder head, up. Put a makeshift plug in the exhaust and poured water in one of the 4 exhaust ports until it was full. Look for traces of water in the intake ports and where the carb bolts up.
HTH, Hendrik