Hi folks, newbie. This question is going to make me look totally stupid, but here goes. I have a Farmall A. 1941 model. I lost fire on the mag. A friend of mine that I see once a year at the Buckley, MI engine show rebuilds mags and did mine. He repaired it with extra new parts and says it throughs about an inch of spark. My problem is, I'm too stupid to figure out how to properly re-install it. Every older tractor I've ever owned has had a battery ignition. I'm looking for someone in the west central area of Michigan, Hersey to be exact, who can come to my home and show me how to do it. We just adopted two small children, so I don't have a lot of money, but I would be able to pay something fair. I've read up on it and have seen different ways of doing it. I can tell you there is a mark on the flywheel as well as on the tractor block and I would guess these need to be aligned. But aligned, they don't seem to be at top dead center. If there is someone out there who can and is willing to help me, I would be forever grateful. Please email Steve at [email protected]. Or call me at 231-912-6130. Thank you for reading my post.
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Nebraska Cowman
Well-known Member
It's pretty simple really. It just needs to fire at or slightly after TDC, never before. the impulse automatically advances it once the engine starts.
Nebraska Cowman
Well-known Member
Right. Provided you have TDC at compression stroke and not exhaust. You will find that moving it a little don't change much.
teddy52food
Well-known Member
Best is to get it to snap at TDC then leave it. If you turn it while running, it will sound and run better when it is advanced. Then if and when someone tries to hand crank it, it will kick back. Also may kick back against the starter and break the nose cone. Put it in and leave the switch off. Turn the flywheel slowly with a bar and watch the mark & listen for the snap. It should be at the mark, never before.
Okay, a couple of more questions and I'll leave you alone. First, do I just ignore the marks on the flywheel and engine block? Second, the number "1" on my distributor cap is not positioned at a particular plug but rather in between two of them. Is that what I want the rotor to point at? And I assume no. one piston is the front cylinder. It's been so long I forgot.
Tom Fleming
Well-known Member
FWIW, I have never used the timing marks on the flywheel or the front pulley. compression stroke on #1, and TDC using a wooden dowel rod in the spark plug hole. Period. 100% success except 1 time where previous owner had the govenor gear out of time with the cam gear. Once the gears were properly timed, success.
IMHO.
IMHO.
Nebraska Cowman
Well-known Member
The 2 O'clock terminal is usually #1.
The cylinder near radiator is No1. Remove that plug and have a helper hand crank the engine while you hold your thumb over the plug until you feel pressure against your thumb. Then drop a long plastic straw on top of the piston and you watch the straw rise as the helper slowly cranks the engine. When the straw quits rising your No1 piston should at TDC on the compression stroke. Remove the cap on the mag and see where your rotor is pointing. If its not pointing to your No1 plug tower you need to pull the mag and rotate the rotor so it's at No1 and reinstall. Should be pointing in the 1 o'clock area. Then see if the engine will start. Hal
What might help is to pull all the plugs, and just slowly turn the engine with the hand crank. With no plugs it's very easy to crank accurately. and you can really get a feel for the timing.
Then you can just put your finger on the number one plug hole (nearest the radiator) to feel if you're on the compression stroke.
Then you can check for tdc.
If you put a long stick/straw in the number one hole, you can see for sure where tdc is, and if it's clicking at or slightly after tdc, which is what you want.
If you're unsure exactly where tdc is (rely on the stick/straw method, not a timing mark) then fail on the slightly "after" tdc side of things.
As long as you do this, you should be close enough to run just fine.
I doubt there'd be any real advantage to fine tuning it further while it's running. You can, but if you do, just be SURE to re-verify afterwards that it's firing AFTER tdc using this manual check method,
As somebody else said, you never know when you might have to hand crank the engine, and having it fire before TDC can break bones.
Also, I know this is probably quite obvious, but just in case it's not... when the mag snaps, it is going to fire on the position the rotor is snapping TO, not from.
Then you can just put your finger on the number one plug hole (nearest the radiator) to feel if you're on the compression stroke.
Then you can check for tdc.
If you put a long stick/straw in the number one hole, you can see for sure where tdc is, and if it's clicking at or slightly after tdc, which is what you want.
If you're unsure exactly where tdc is (rely on the stick/straw method, not a timing mark) then fail on the slightly "after" tdc side of things.
As long as you do this, you should be close enough to run just fine.
I doubt there'd be any real advantage to fine tuning it further while it's running. You can, but if you do, just be SURE to re-verify afterwards that it's firing AFTER tdc using this manual check method,
As somebody else said, you never know when you might have to hand crank the engine, and having it fire before TDC can break bones.
Also, I know this is probably quite obvious, but just in case it's not... when the mag snaps, it is going to fire on the position the rotor is snapping TO, not from.
Thank you all very much. I know I sound kind of stupid here. I'm actually pretty decent at wrenching. I've just never done a mag. My H and Super M both have battery ignitions, pretty easy. It just kept getting harder and harder to start. The spark was barely orange. The guy that did the rebuild is a friend of a friend that does a million of these. He used some extra new magnets he had lying around went through it and timed it, all for free. It has new internal ignition components and coil as well as cap and rotor. It should be ready to go. I also bought a brand new carb for it. I hope it's adjusted right. I would imagine about 1 1/2 turns out on the jet screw should be close. The tractor has been in my family since it was new in 1941. Always garaged. It's been sitting in my shop for 2 years and I want it running. So I know what I'm working on this weekend. Again, thanks to all.
Having never done something doesn't make you stupid, just inexperienced with a mag. You're wise to ask the questions first instead of later!
Now if you were to spend an evening pouring over sparkplugs, and wires, and points, and valves, and this and that, all trying to figure out why the *&^#& your tractor's suddenly running like crap and blowing black smoke...
... only to realize an hour and a half later that you never pushed the choke rod in... now THAT's stupid.
(I did that last night)
Now if you were to spend an evening pouring over sparkplugs, and wires, and points, and valves, and this and that, all trying to figure out why the *&^#& your tractor's suddenly running like crap and blowing black smoke...
... only to realize an hour and a half later that you never pushed the choke rod in... now THAT's stupid.
(I did that last night)
Tom Fleming
Well-known Member
Yes, Delco made the distributor, and they can be found, but hold on to your wallet. They appear on eBay every so often.
One more question guys. Since the mag has been rebuilt, it has been rotated several times,that doesn't throw anything out of whack does it? The engine has not been disassembled other than just removing the mag. I was told today that there are two gears inside the mag that must be aligned when installing the mag. Does just rotating the assembled mag throw these gear out of time?
Tom Fleming
Well-known Member
who rebuilt the mag? if you had the rotor assembly out, yes, there are timing marks. if you had it rebuilt for you, then the shop should have already done that. If all you did was take the mag off and did nothing else to it, then you should be fine. If you took the mag apart yourself, then yes, check the timing of the rotor gear to the main shaft. Otherwise, nothign for you to do.
I had it professionally rebuilt. Steve told me on his bench it shot about a 1" spark. The mag itself has been rotated several times since the rebuild, but has not been disassembled. I had no reason to. So it should be okay? Every time it snaps, the points should be opening for that particular cylinder, correct? So if it has not been taken apart since the rebuild, everything will be as it should, or at least how it was put together? I'll find out Saturday, that's when I'm tearing into it. Damn, why didn't they just put a distributor on these things. My H, Super M and 400 with distributors are simple. I'm probably worried about nothing. Just want it to go smooth. I guess taking the cap off and rotating it until it's ready to spark on number one and then putting the cap back on should do the trick.
bjb in TX from Ne
Member
Is #1 different on the IH mags? I know for FMJ #1 is 10 o'clock.
John M
Well-known Member
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Bigger deal is being made of it than it needs to be. If its on, and doesnt run, or backfires, or just seems to turn over funny, take the mag back off, turn it 180 degrees, simple. (This is assuming you have the plugs on right.) Its not much different than a distributor, except you can only put it on wrong or right!! (Also assuming the only thing you took off was the magneto itself.)
Jim Becker
Well-known Member
f you know how to install a battery ignition unit,you can install a magneto. You just need to deal with 2 things.
1) Turn the magneto backwards to get the rotor pointing in the right direction. This avoids having the impulse coupling latch in.
2) After you install it, rotate the engine slowly with the crank. When the timing marks are in line, rotate the top of the mag out until the impulse clicks. Then rotate the engine slowly one more revolution, watch the timing mark. The impulse coupling should click exactly as the timing mark reaches alignment. If it doesn't rotate the top of the mag out for more advance or the opposite way for less and recheck.
Tom Fleming
Well-known Member
FWIW, I replaced most of my battery ignitions with magnetos. doesn't matter if your battery is dead. All my F series tractors do not have batteries or starters. They fire right up. My letter series tractors are a mix of Mag and dist. And honestly, the mags fire up quicker than the (not by much, but a fact).
So, each person needs to decide what they like best. Take a minute, search the internet, and read about mags. You may end up liking them.
So, each person needs to decide what they like best. Take a minute, search the internet, and read about mags. You may end up liking them.
Livin the Dream
Member
Scatter:
I have a Super A and just went through the same things you are dealing with. Believe me when I say that by [b:41649a9efd]you[/b:41649a9efd] getting your mag in and running you will be the happyiest person around because you did it, not your friend, not your buddy but you....and if you ever have a problem again you will know exactly what to do.
On you distributor cap you want your rotor pointing to the cylinder just above the #1 printed on that cap....if you follow that wire it goes to number one cylinder on your engine. It's easy to get your number one cylinder on TDC, pull the plug like the guys have said...I reached down with my hand crank and slowly rotated the crank while with my thumb over the number one cylinder hole could feel pressure blowing out...you know your on the compression stroke. Then as soon as I could feel pressure I knew it was the compression stroke I took a flashlight and simply watched as the cylinder inside came to the top...you can actually see it....no need for a straw..you can also then see as the cylinder starts to go down....you've gone to far....don't panick I was able to just reach in grab the fan blade and slowly turn the fan blade until the cylinder went back to the very top. That's TDC.... Your mag must be pointing to #1 cylinder on your cap for it to start. You can manually turn your rotor so the mag is pointing to #1 as you line it up to connect it. You'll get it and you'll be thrilled you did. Like the guy said....you will never have to worry about your battery going dead and you will be able to start it anywhere with a mag....there the best.
I have a Super A and just went through the same things you are dealing with. Believe me when I say that by [b:41649a9efd]you[/b:41649a9efd] getting your mag in and running you will be the happyiest person around because you did it, not your friend, not your buddy but you....and if you ever have a problem again you will know exactly what to do.
On you distributor cap you want your rotor pointing to the cylinder just above the #1 printed on that cap....if you follow that wire it goes to number one cylinder on your engine. It's easy to get your number one cylinder on TDC, pull the plug like the guys have said...I reached down with my hand crank and slowly rotated the crank while with my thumb over the number one cylinder hole could feel pressure blowing out...you know your on the compression stroke. Then as soon as I could feel pressure I knew it was the compression stroke I took a flashlight and simply watched as the cylinder inside came to the top...you can actually see it....no need for a straw..you can also then see as the cylinder starts to go down....you've gone to far....don't panick I was able to just reach in grab the fan blade and slowly turn the fan blade until the cylinder went back to the very top. That's TDC.... Your mag must be pointing to #1 cylinder on your cap for it to start. You can manually turn your rotor so the mag is pointing to #1 as you line it up to connect it. You'll get it and you'll be thrilled you did. Like the guy said....you will never have to worry about your battery going dead and you will be able to start it anywhere with a mag....there the best.
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