| Author |
 Topic Search  Topic Options
|
BillyLawson 
Bronze Level
Joined: 19 Sep 2016
Location: Mill Creek, IN
Points: 9
|
 Post Options
 Thanks(0)
 Quote  Reply
 Topic: 1948 C Magneto/Spark Plug Problem
Posted: 19 Sep 2016 at 9:25pm |
I have just installed a rebuilt Fairbanks Morse magneto into my 1948 C.
I can start it up by hand, but when I put the tractor under load or even try to drive it normally, it will spit, sputter, and pop. It also sometimes does this while idling.
I checked #1 cylinder and #3 cylinder and they look damp to the point of falling out, and slightly corroded. #2 and #4 are clean.
What is going on? Is this the mag? Because the mag that I took off - I just could not start it up by hand. Now, occasionally, if I was quick to release on the clutch, it would pop and sputter a little - but not at idle. But it appears that the original one, the one NOT rebuilt, ran better than this one.
Also, why is the background for typing this message black? I cannot figure out how to change it.
Thank you in advance.
Edited by BillyLawson - 20 Sep 2016 at 10:32am
|
 |
|
Sponsored Links
|
|
|
DougS
Orange Level
Joined: 03 Nov 2011
Location: Iowa
Points: 2490
|
Post Options
Thanks(0)
Quote Reply
Posted: 19 Sep 2016 at 9:29pm |
|
This sounds like a fuel problem. Check and see if fuel flows from the tank to the carb. If this check good then check the carb itself.
|
|
BillyLawson
Bronze Level
Joined: 19 Sep 2016
Location: Mill Creek, IN
Points: 9
|
Post Options
Thanks(0)
Quote Reply
Posted: 19 Sep 2016 at 9:43pm |
|
Now I did pull a wire just a little under a 1/4" on the #1 cylinder when it was running.
I got arching, but then some skipping.
Could this be the mag, or just bad plugs in #1 and #3?
Again, typing this with a black background and white letters, and then I have to change it to black letter for you all to be able to read this.
|
|
steve(ill)
Orange Level Access
Joined: 11 Sep 2009
Location: illinois
Points: 86529
|
Post Options
Thanks(0)
Quote Reply
Posted: 19 Sep 2016 at 10:10pm |
are you sure you don't have the 1 and 3 plug wires switched ?
-
or other ?
Edited by steve(ill) - 19 Sep 2016 at 10:12pm
|
|
Like them all, but love the "B"s.
|
|
BillyLawson
Bronze Level
Joined: 19 Sep 2016
Location: Mill Creek, IN
Points: 9
|
Post Options
Thanks(0)
Quote Reply
Posted: 19 Sep 2016 at 10:17pm |
I left the wires hook up to the engine and the original cap to the original mag.
I installed the new mag with the new cap already on it and then wire by wire hooked it up, and did the same with the new wires.
From what I know/saw online, the firing order is 1-2-4-3. If someone can correct me if I'm wrong, I'd be grateful.
Could it be that the very first spark plus (closest to the radiator) and the last one (closest to the gas tank) - could the cores of those spark plugs be gradually going bad? Could this be stopping it from getting a good enough spark? The spark plug themselves I did not change.
Edited by BillyLawson - 19 Sep 2016 at 10:20pm
|
|
nella(Pa)
Orange Level Access
Joined: 11 Sep 2009
Location: Allentown, Pa.
Points: 3114
|
Post Options
Thanks(0)
Quote Reply
Posted: 19 Sep 2016 at 10:35pm |
|
The firing order is correct, 1243
|
|
WF owner
Orange Level
Joined: 12 May 2013
Location: Bombay NY
Points: 4937
|
Post Options
Thanks(0)
Quote Reply
Posted: 20 Sep 2016 at 6:27am |
|
Are the gears (rotor) inside the mag timed correctly? If the gears are one tooth off, you will get a weak spark that will allow the engine to run, but it won't run right or have any power.
|
|
Hubert (Ga)engine7
Orange Level
Joined: 12 Sep 2009
Location: Jackson Cnty,GA
Points: 6430
|
Post Options
Thanks(0)
Quote Reply
Posted: 20 Sep 2016 at 7:22am |
|
All the previous suggestions are correct and there could be more than one item contributing to the problem. Also try a fresh set of spark plugs, Autolite 295/303 or AC 45/47 do not use Champion. The wires could be bad also. You need solid core wires not the carbon core.
The black background automatically goes away when you hit post and the message goes on the thread.
|
|
Just an old country boy saved by the grace of God.
|
|
CTuckerNWIL
Orange Level
Joined: 11 Sep 2009
Location: NW Illinois
Points: 22824
|
Post Options
Thanks(0)
Quote Reply
Posted: 20 Sep 2016 at 8:27am |
|
Do you have resistor wires in place? Solid core wires and NON resistor plugs are needed for a magneto.
If it we me, I would swap out the plug wires on 1 and 3 just to see what happens. By your description it sounds just like my x son in laws M Farmal after he did a "tune up" and got 2 wires crossed.
|
|
|
|
Gerald J.
Orange Level
Joined: 12 Sep 2009
Location: Hamilton Co, IA
Points: 5636
|
Post Options
Thanks(0)
Quote Reply
Posted: 20 Sep 2016 at 9:52am |
|
You need to check and adjust the timing. its varied by the point gap and the tilt of the magneto. The magneto does not have a centrifugal advance to advance the spark for higher speed running. Retarded spark reduces power but an engine runs smooth. Advanced spark makes an engine run rough because spark too far before top dead center pushes against the rising piston. The magneto does retard the spark at cranking speed to keep it from kicking back on the crank or the starter with the impulse mechanism that doesn't work at engine idle speed generally.
And proper plugs and wires are important, Champion tractor plugs are junk when new and get worse with age, their ceramic doesn't clean from heating.
Gerald J.
|
|
Tcmtech
Orange Level
Joined: 15 Apr 2015
Location: Minot ND
Points: 310
|
Post Options
Thanks(0)
Quote Reply
Posted: 20 Sep 2016 at 11:58am |
A weak and or skipping spark on any plug wire would indicate any or a combination of these. Worn out points, Points that are out of adjustment, Condenser that may be bad or going bad, Worn out cap and rotor Incorrect timing between the points and when the rotor is pointing at a cap terminal. Have resistor wire on a system that should never have any.
It may be worth your time to pull the magneto and set it up on a workbench with the related plug wires and spark plugs wired up so you can spin it with a drill while looking at everything in live action.
The only way you will determine if your point to cap and rotor timing is correct is to sacrifice a cap and cut a window in the side just under one of the plug sockets so you can see the actual rotor and the related cap terminal to confirm the spark is where it needs to be when the rotor passes by and that plug line is firing.
Also putting a timing light to it while watching that plug line fire will give you a stop motion view of the actual rotor to cap alignment.
I've had to do that test with a number of magnetos and old distributors that just would not setup right when working on my stuff or friends stuff before. And usually someone gets wound up when you start sawing up their precious cracked up weather rotted distributor cap to put a window in the side too. Apparently those things are some sort of irreplaceable one of kind component? 
I have found a few where I had to move the drive gear timing up or back one tooth from where their indexing marks showed to correct get the points timing to cap terminal timing to line up due to odd mismatches in parts.
As much as we hate to admit it, the reality is quality control on some things back then was as sloppy as it is now and 40 - 70+ years of age plus sloppy tolerances on remakes of old parts just makes it worse and guy has to cheat a bit to make it work right.
Edited by Tcmtech - 20 Sep 2016 at 12:01pm
|
|
BillyLawson
Bronze Level
Joined: 19 Sep 2016
Location: Mill Creek, IN
Points: 9
|
Post Options
Thanks(0)
Quote Reply
Posted: 20 Sep 2016 at 6:42pm |
Thank you for the great info so far.
Does anyone know where I can find a diagram for this magneto? I don't know where the teeth are supposed to be.
Thank you again for patience as I expose my ignorance.
|
|
BillyLawson
Bronze Level
Joined: 19 Sep 2016
Location: Mill Creek, IN
Points: 9
|
Post Options
Thanks(0)
Quote Reply
Posted: 20 Sep 2016 at 8:51pm |
|
Not for nothing, I just noticed a hairline crack on the big cap housing.
|
|
Tcmtech
Orange Level
Joined: 15 Apr 2015
Location: Minot ND
Points: 310
|
Post Options
Thanks(0)
Quote Reply
Posted: 20 Sep 2016 at 8:57pm |
Is there a specific model number to your magneto?
It would greatly narrow down the troubleshooting and parts searches.
On the chance that there is limited easy to find info being you have two units you could take one apart and draw up a simple schematic you can follow to identify what part came out in what order and just do a bit of self education.
Magnetos are not overly complex devices and pretty much every component only has one way it fits back together.
It's a good way to get to know your beast and how to tame it.  Oh yea, magnetos tend to have a much lower peak voltage but higher current than modern vehicle ignition systems so if you get to cranking it over by hand it might pop you a good one that really stings!  
Edited by Tcmtech - 20 Sep 2016 at 9:52pm
|
|
Chalmersbob
Orange Level
Joined: 11 Sep 2009
Location: Pennsylvania
Points: 2122
|
Post Options
Thanks(0)
Quote Reply
Posted: 20 Sep 2016 at 9:37pm |
|
Remove #1 plug and turn the engine over with a hand crank and your thumb in the plug hole. Turn the engine until you feel air coming out of the plug hole. This is the compression stroke. Now remove the distributor cap from the mag and check the position of the rotor. It will be pointing at the #1 wire position. If this does not correspond to the #1 plug wire on the cap then change it and install the remaining wire in 1243 order. LOL Bob
|
|
4 B's, 1 C's,3 CA's, 2 G's WD, D14, D15, B-1, B10, B12, 712S,
|
|
WF owner
Orange Level
Joined: 12 May 2013
Location: Bombay NY
Points: 4937
|
Post Options
Thanks(0)
Quote Reply
Posted: 21 Sep 2016 at 7:26am |
If magneto (internal) timing is your problem (which I suspect it is), this page may help.
Edited by WF owner - 21 Sep 2016 at 7:27am
|
|
BillyLawson
Bronze Level
Joined: 19 Sep 2016
Location: Mill Creek, IN
Points: 9
|
Post Options
Thanks(0)
Quote Reply
Posted: 25 Sep 2016 at 6:21pm |
THANK YOU all so much! I sent the rebuilt magneto back, and the original one is back on.
#1 and #3 spark plugs are still wet, even with the original magneto back on. These spark plugs are new, as well as the wires and distributor cap. When it runs smooth, it does a half @ssed, light backfire. But, when it starts to run rough, I have pretty much good power and no chug. AND no half @ssed backfire.
Is this a valve adjustment needing to happen??
I'm not losing any antifreeze nor oil. The head was rebuilt a couple years ago. I have been adding lead substitute to my fuel and Marvel's Mystery Oil. Have I overdone it in the mixture?
Edited by BillyLawson - 25 Sep 2016 at 6:23pm
|
|
