46 C w/magneto help
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Category: Allis Chalmers
Forum Name: Farm Equipment
Forum Description: everything about Allis-Chalmers farm equipment
URL: https://www.allischalmers.com/forum/forum_posts.asp?TID=143732
Printed Date: 01 Nov 2025 at 12:47am
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Topic: 46 C w/magneto help
Posted By: CAL(KS)
Subject: 46 C w/magneto help
Date Posted: 23 Oct 2017 at 8:33am
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I have a 46 C im trying to get going and the damn thing just wont stop fighting me. iv had it running but it just runs like crap. When I have the tractor on #1 compression, the mag drive slot is not horizontal. I tried to mess with the rotor timing in the mag but it either does nothing or sputters badly. I am cranking the tractor with a starter and the mag has good spark. I have pulled the mag about 17 times trying to get things lined up. I don't have a hand crank so lining up #1 compresson is a pain using the belt and fan. Can I assume correctly that no amount of changing the rotor timing in the mag is going to fix it because the impulse is not happening at the correct time and ill have to pull the cover and retime the governor gear? Thought at first I had a carb issue as it would start and run but poorly and the tank was full of junk. Cleaned the tank and rebuilt the carb (it was full of rust and gunk) and same problem so started on the mag.
------------- Me -C,U,UC,WC,WD45,190XT,TL-12,145T,HD6G,HD16,HD20 Dad- WD, D17D, D19D, RT100A, 7020, 7080,7580, 2-8550's, 2-S77, HD15 |
Replies:
Posted By: Bill Long
Date Posted: 23 Oct 2017 at 3:32pm
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If you impluse spring is broken - that is when you turn it over mounted in a vice you do not hear a click - they you are at least 180 degrees out of time. You may want to send it to a shop for repair. Steve at B&B is a sponsor on this site. He will have the parts and the knowledge to fully repair your mag. Perhaps you can find a more local mechanic. In any event hope it comes out well. Good Luck! Bill Long
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Posted By: PaulB
Date Posted: 23 Oct 2017 at 3:35pm
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I have a good magneto on a running engine that I'll sell for $120 plus the shipping. ------------- If it was fun to pull in LOW gear, I could have a John Deere. Real pullers don't have speed limits. If you can't make it GO... make it SHINY |
Posted By: Dick L
Date Posted: 23 Oct 2017 at 5:47pm
| I always test a magneto in a vise using a spark plug wire from the cap and watching the spark from the wire end to the magneto case. I make sure I have a good spark from each wire. Without a hand crank you can find the compression top dead center by removing the valve cover and make sure both rocker arms are up with a gap under both valves. I find it easier to back the engine up to where the magneto drive will line up without having tension on the impulse spring. Make sure the next time the impulse snaps it is going to fire number one plug wire before mounting the magneto. I do this in the vise when testing for spark then tape the drive so it can not turn backwards. It can turn back all day long and you will not know which wire it will fire on after mounting. |
Posted By: saele
Date Posted: 24 Oct 2017 at 7:16am
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You can remove the mag gear by removing the small screw that locks it in. Seems to me I had to move my gear on my C one notch to get it in the right gear slot and bring it horizontally. It is irritating that I can't remember anything anymore, I just did this to my C this Spring and have forgotten the details. I am now asking myself why I didn't have the gear lined up correct in the first place. I am in the golden age you know. Take a look at it and also your manual. |
Posted By: CAL(KS)
Date Posted: 24 Oct 2017 at 7:42am
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Guys, the mag is working fine. My issue is I was treating it like a distributor, trying to line up the rotor when the engine was on #1 tdc. I guess I came to the realization that since the mag drive slot it not horizontal on #1 tdc, the inpulse action of the mag would not be timed correctly and thus the reason im having trouble. Correct? what im saying is, since the governor gear is not timed correctly, it would cause the impulse to trip at the wrong time even if I have the rotor on #1. I think I have answered my own question, but im just trying to verify my line of thinking is in the right direction. if it was a distributor, actual rotor positon does not technically matter, but in a magneto it has to correlate with the impulse. ------------- Me -C,U,UC,WC,WD45,190XT,TL-12,145T,HD6G,HD16,HD20 Dad- WD, D17D, D19D, RT100A, 7020, 7080,7580, 2-8550's, 2-S77, HD15 |
Posted By: Dick L
Date Posted: 24 Oct 2017 at 8:34am
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The governor gear "must" be timed horizontal at top dead center on the compression stroke as in the picture below. You can check this with the TDC or CENTER line in the center of the inspection hole. In the vise is where you can snap the impulse and watch for the spark to know when the gears are lined up properly. If you gear has the marking on then you need to engage the C over the taper tooth on the small gear. 
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Posted By: CAL(KS)
Date Posted: 24 Oct 2017 at 8:39am
Yes. Thank you. I thought so, just needed to verify. All I have for model c is IT manual and as you know they don't show jack. Apparently this is why the PO never got it running after he bought it. Can the governor gear be retimed by removing the cover or does the entire front plate need to come off? ------------- Me -C,U,UC,WC,WD45,190XT,TL-12,145T,HD6G,HD16,HD20 Dad- WD, D17D, D19D, RT100A, 7020, 7080,7580, 2-8550's, 2-S77, HD15 |
Dick L wrote:Posted By: Dick L
Date Posted: 24 Oct 2017 at 10:09am
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You can pull the gear out the front after the governor housing has been removed on the B and C's. Make sure the piston is at top dead center when sliding the governor gear back in. I would worry as to why it was not timed correctly and if the camshaft gear was timed correctly as well. I would check the rocker arms were all the way up on both valves at top dead center on the compression stroke before deciding not to removing the timing gear cover/front engine gear cover. I have a problem of trusting myself with out double checking let alone trusting someone else.   
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Posted By: CAL(KS)
Date Posted: 24 Oct 2017 at 11:49am
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I will verify the cam timing when I pull the governor gear. I had the valve cover off and was watching #1 intake to verify tdc and when piston is up both valves are closed but its possible to be off a tooth or 2. When I got the tractor the governor housing was loose as if it had been removed, I suspected, to repair the throttle pivot pin/oil tube as it was loose in the housing. so who knows!? ------------- Me -C,U,UC,WC,WD45,190XT,TL-12,145T,HD6G,HD16,HD20 Dad- WD, D17D, D19D, RT100A, 7020, 7080,7580, 2-8550's, 2-S77, HD15 |
Posted By: Gerald J.
Date Posted: 24 Oct 2017 at 12:00pm
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I have the AC shop manual for G, B, C, and CA on line at: http://geraldj.networkiowa.com/Trees/Allis-Chalmers-G-B-C-CA-Service.pdf" rel="nofollow - http://geraldj.networkiowa.com/Trees/Allis-Chalmers-G-B-C-CA-Service.pdf It is much better than the simplified I&T manual. I also have a magneto shop manual there: http://www.geraldj.networkiowa.com/Trees/FM-Xmagneto.pdf" rel="nofollow - http://www.geraldj.networkiowa.com/Trees/FM-Xmagneto.pdf Gerald J. |
Posted By: TomMN
Date Posted: 25 Oct 2017 at 8:23am
| TDC can be found by looking at the set screw on the front crankshaft pulley. the keyway from the factory lines up with the crank journals. On a B, C, CA you'll see it pointing pointing straight up when 1 and 4 pistons are at TDC and straight down when pistons 2 and 3 are at TDC. The other way on a WC, WD engine. I might be remembering this backwards but as you are turning the crankshaft it is easy to follow it. As air is pushing out from the spark plug hole on number one, start looking at the set-screw and continue turning until it is vertical whether it is down or up. Of course if someone has welded up the crankshaft and machined a new keyway all this goes out the window but I have never seen one not lined up. |
Posted By: Ted J
Date Posted: 25 Oct 2017 at 10:13am
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Tom, I'll have to take a video of you doing that at Hutch next year. it saved me a LOT of time and aggravation!! OR, you could do it yourself and post it to your web site. ------------- "Allis-Express" 19?? WC / 1941 C / 1952 CA / 1956 WD45 / 1957 WD45 / 1958 D-17 |
Posted By: CAL(KS)
Date Posted: 25 Oct 2017 at 10:39am
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YES. Tom I got to thinking and went to your website and looked at the magneto timing. Then did the head smack (doh). if I would have looked in the timing gear section of my book im sure its in there but was flusterd and trying to find it in the electrical/ignition section lol ------------- Me -C,U,UC,WC,WD45,190XT,TL-12,145T,HD6G,HD16,HD20 Dad- WD, D17D, D19D, RT100A, 7020, 7080,7580, 2-8550's, 2-S77, HD15 |
Posted By: Dick L
Date Posted: 25 Oct 2017 at 11:36am
| Didja gitter goin?? |
Posted By: CAL(KS)
Date Posted: 25 Oct 2017 at 11:43am
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not yet, between harvesting and family stuff havnt had a chance to work on it. mom and kids will be gone a couple days end of this week so ill have time then. ------------- Me -C,U,UC,WC,WD45,190XT,TL-12,145T,HD6G,HD16,HD20 Dad- WD, D17D, D19D, RT100A, 7020, 7080,7580, 2-8550's, 2-S77, HD15 |
Posted By: CAL(KS)
Date Posted: 27 Oct 2017 at 8:26am
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Ok guys. lined up the governor gear and slapped the mag back on last night and purred like a kitten. (Like the V8 commercial, slaps forehead). Assuming the PO knew what he was doing cost me a lot of time. you never know what you will get into with these old tractors. ------------- Me -C,U,UC,WC,WD45,190XT,TL-12,145T,HD6G,HD16,HD20 Dad- WD, D17D, D19D, RT100A, 7020, 7080,7580, 2-8550's, 2-S77, HD15 |
Posted By: Dick L
Date Posted: 27 Oct 2017 at 11:18am
| Good Deal! |
Posted By: TomMN
Date Posted: 27 Oct 2017 at 2:42pm
| Glad to hear you got it figured out. I really like the pictures Dick L has of the timing gears and the mag-drive slot all lined up like that. |
Posted By: Bill Long
Date Posted: 27 Oct 2017 at 3:01pm
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Congratulations!!! Glad to see another AC back to life. Good Luck! Bill Long |