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Magnetos, Ignition Coils and Spark Plugs Discussion about magnetos, buzz coils, spark plugs, ignitors and low tension coils.

Magnetos, Ignition Coils and Spark Plugs

Fairbanks-Morse Magneto FM-X4B3A


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  #1  
Old 02-11-2010, 03:53 PM
Deerlope Deerlope is offline
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Default Fairbanks-Morse Magneto FM-X4B3A

I need any info that I can find on a Fairbanks-Morse Mag type FMX4B3A serial # 3627094. Stamped on a fiber gear in it are the letters C & A. What do they refer to and what is the points setting. This is on a very old Continental engine that is driving a welder at present.
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Old 02-11-2010, 04:28 PM
Dempster Dempster is offline
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Default Re: Fairbanks-Morse Mag

FM-X4B3A is 4 cylinder CW drive mag for a Allis Chalmers tractor engine and unless the impulse has been changed it will have a 30° impulse hub. It may have been changed and be okay but the 3 in the number designates is for Allis Chalmers. Most Continental engines on a welder like F162 & F163 would use a FM-X4B16 or FM-J4B16 mag the 16 designates them for Continental and there would be a A or other letter after those numbers whether it had a 15° or 20° impulse hub. 15° is the impulse used on overhauling one today for a Cont F163 or F162 ran on today's gasoline. The dist rotor fiber gear should be lined up with C mark because that should be a CW clockwise drive rotation mag for AC or Cont engines. The A mark is only used for CCW or anti-clockwise drive mags the rotation is determined by facing mag drive end and which direction it turns to make the impluse trip. Points setting for FM-X mag is .015" .

magneto manuals:

http://www.oldengine.org/members/die.../PetrolMag.htm
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Old 02-11-2010, 04:37 PM
K D Redd K D Redd is offline
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Default Re: Fairbanks-Morse Mag

The A and C on the fiber gear that drives the rotor bug is to time the rotor bug to the mag. One is used if the mag turns clockwise "C", one is used when the mag turns counter clockwise "A". The "A" stands for anti-clockwise or counter clockwise. If you will look closely at the metal gear on the mags rotor you will see one tooth that has a corner knocked off. This is the tooth you time to. I have worked with these mags on Allis-Chalmers four cylinder engines. Seeing the mark to time is almost impossible. On the FM mags the Allis engines used, there is a raised area in the chamber where the bug turns. This raised area is at about the 10 O'clock position. I turn the mag until the rotor is locked by the impulse dogs. I then put the cap on the mag. Point setting is .020 inch. You did not say if this is on a four or six cylinder engine.

Kent
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Old 02-11-2010, 05:00 PM
Deerlope Deerlope is offline
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Default Re: Fairbanks-Morse Mag

The engine is a 4 cyl. Sorry but I am very new to all of this. Thank you.
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Old 02-11-2010, 06:05 PM
Dempster Dempster is offline
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Default Re: Fairbanks-Morse Mag

The C mark on fiber gear lines up with a beveled tooth or dot or punch mark on the small metal gear. You told us how many cylinders with the mag spec FM-X4B3A. Tell us what model Continental engine it is and the welder brand and model but a 15 deg CW drive mag will work on all those F162 or F163 engines that were standard in Lincoln SA200 and other welders. I've seen those fiber gears have the shaft slip or marked wrong from brand new it happens. To be sure it is lined up right make sure the dist rotor is coming up in line with the timing tab mark inside the cover with dist cap off and points are just starting to open.

This is for the J mag that is similar but points setting are different.

http://www.worldpath.net/~thompson/a.../magtiming.htm

FM = Fairbanks Morse

X= model X, HT Magneto, Jump Spark Distribution, Oilite Bearing Cam End, Ball Bearing Drive End

4 = 4 cylinder

B = flange mount

3 = Allis Chalmers application

A variation = CW drive, 30 degree impulse.

http://www.oldengine.org/members/die.../MagFMType.htm

FM-X4B16 or varitions A-1, B, C-1, G, R, & V would have 15 degree impulse drives.

FM-X4B16 variations A, C, E, F & K will have 20 degree impulse. Any of those would be correct for a Continental F162 or F163 4 cyld engine. If the FM-X4B3A has a 30 deg the hub can be changed out for a 15 or 20 deg and still work fine same mag otherwise only different impulse hub.
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Old 02-11-2010, 06:08 PM
Dempster Dempster is offline
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Default Re: Fairbanks-Morse Mag

The C mark on fiber gear lines up with a beveled tooth or dot or punch mark on the small metal gear. You told us how many cylinders with the mag spec FM-X4B3A. Tell us what model Continental engine it is and the welder brand and model but a 15 deg CW drive mag will work on all those F162 or F163 engines that were standard in Lincoln SA200 and other welders. I've seen those fiber gears have the shaft slip or marked wrong from brand new it happens. To be sure it is lined up right make sure the dist rotor is coming up in line with the timing tab mark inside the cover with dist cap off and points are just starting to open.

This is for the J mag that is similar but points setting are different.

http://www.worldpath.net/~thompson/a.../magtiming.htm

FM = Fairbanks Morse

X= model X, HT Magneto, Jump Spark Distribution, Oilite Bearing Cam End, Ball Bearing Drive End

4 = 4 cylinder

B = flange mount

3 = Allis Chalmers application

A variation = CW drive, 30 degree impulse.

http://www.oldengine.org/members/die.../MagFMType.htm

FM-X4B16 or varitions A-1, B, C-1, G, R, & V would have 15 degree impulse drives.

FM-X4B16 variations A, C, E, F & K will have 20 degree impulse. Any of those would be correct for a Continental F162 or F163 4 cyld engine. If the FM-X4B3A has a 30 deg the hub can be changed out for a 15 or 20 deg and still work fine same mag otherwise only different impulse hub.
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Old 02-11-2010, 06:22 PM
Deerlope Deerlope is offline
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Default Re: Fairbanks-Morse Mag

Here is the info off the unit

SA-200-F162,code 4150, serial# 427840
Fairbaks-Morse mag # FMX 4B3A
Serial # 3627094
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Old 02-11-2010, 10:23 PM
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Reed Engine Reed Engine is offline
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Default Re: Fairbanks-Morse Mag

Demp, what exactly is the difference between a Red Seal mag and a WD or a G226 Allis?
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Old 02-12-2010, 02:16 AM
Dempster Dempster is offline
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Default Re: Fairbanks-Morse Mag

Your welder was made in 1961. Can enter the code number at Lincoln and find the manuals for it.

http://www.mylincolnelectric.com/Cat...ualsearch.aspx

Wisconsin Motors has the manuals for L Head (flathead) F series Continental engines.

http://www.wisconsinmotors.com/partcatalog-ex.html

If the mag came on it and it starts and runs fine it's probably okay if starts hard or doesn't time right probably has wrong impulse. What I'm saying is if you got the mag else where with that number it could have the wrong 30 degree impulse it's set up for Allis Chalmers or others needing a 15 or 20 deg impulse hub. The difference is the impulse has a different keyway in it at different place so that hub has to be changed. The impulse with the trip weights on it under the drive cup is stamped with the degree number. That is the only way to change the impulse degree setting on FM mags is change the hub you don't have variable adjustment like on a Wico or American Bosch mags.
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Old 02-12-2010, 08:52 AM
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Default Re: Fairbanks-Morse Mag

I take that to mean the lag angle. So the Allis stamped mag may in reality be a Red Seal mag if a mag man who knew what he was doing put the correct hub/shell on the impulse? I guess if you want to be politically correct when you change a thing like that you should re-stamp the number code. Like that would ever happen.
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Old 02-12-2010, 12:52 PM
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Default Re: Fairbanks-Morse Magneto FM-X4B3A

Yes Reed, The impulse lag angle. CW drive AC mags is 30° vs. 15° or 20° for CONTINENTAL. 15° for Continental has been the recognized one to go with on those old flat heads for a long time when putting new impulse drive parts on them because all those engines are running on higher octane gasoline or unleaded now. The impulse drive shell is the same it's the impulse hub with trip weights has different keyway. Trying to make up that 15° difference with the slots on the mag housing or trying to turn the governor and cam gears off time isn't going to make it work right and many try that finally realizing they got the wrong mag. Yes someone should restamp the mag number or at least stamp 15° on it someplace so someone would know. I restamp them but most don't or never have. If a guy had the little plastic FM guage that you measure lag angle with the could know that without taking it apart or ran it on a mag test stand with a synchrometer and measure it. You said a "red seal" mag yep I know you mean Continental red seal engines but a real mag man might mistake you talking about a silicone red seal in the magneto instead ? I haven't used those red seals in FM welder mag or any FM mags for years they are over priced and leak asking for trouble on a old engine someone won't spend the money to get overhauled.
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Old 02-12-2010, 08:13 PM
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Default Re: Fairbanks-Morse Magneto FM-X4B3A

Demp, Red Seal is the Continental engine model. They often say Red Seal on the exhaust. At least I've seen several that said that.
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Old 02-13-2010, 11:02 PM
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Default Re: Fairbanks-Morse Magneto FM-X4B3A

Ed, Yes I know what the red seal Continental engine is. Just messing with you lol. I probably wasn't explaining the impulse to him like should have that's what happens when you don't see the sun for a week but it finally came back yesterday. So you never used those red FM silicone oil seals in the FM J or X mags ? I hated those when Continental wanted them put in their mags always put the black rubber one back in instead and then no more leaking.
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Old 02-21-2010, 04:24 PM
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Default Re: Fairbanks-Morse Magneto FM-X4B3A

Demp, I'll say this, you know more about these old mags than a mere mortal should.
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