Walter beck

New User
On a farm all a should you set points at 13 or 20 ?. I have a magnito system with a 12 volt coil and battery. Using condenser that come in 12 volt point set. Also is there a difference in condensers between mag and distributor?
 
I would keep the "mag's" original point setting because I believe that has more to do with the shape of the cam than whether the points are "firing" the original mag coil or a battery-powered external coil.

There's likely a small difference in condenser capacity between the original mag condenser and what would have been used with the "battery ignition" coil you are using.

If point life is good, don't worry about it.

If points pit on one side and build up metal on the other, condenser capacity is off, and I would install (externally) a condenser that matches the application of the coil you are using.
 
Based on units Ive seen and worked on, there is some relatively small difference in Condensor ratings in Mags versus battery powered coil ignitions but I don't have any particulars for you. It has to do with the Inductance of the Coil matching up with the Capacitance of the condenser and many coils are physically bigger with higher inductance then a smaller mag coil. Likewise many coil ignitions have a slight wider points gap but that also depends on other factors like 4 or 6 or 8 cylinders and make and models etc etc SO YOU JUST HAVE TO LOOK AT THE SPECS AND GO FROM THERE.

As far as points gap in a magneto, whats critical and where points should actually be set is so they just break open when coil current is at its peak and that occurs just as the magnetic portion of the rotor is leaving the laminated armature. On a Wico X mag coil current peaks when the magnet is 0.090 out of the laminations so the points should be set (referred to as the Edge Gap Setting) so they just break open at that time. Now when all was new and in spec and no wear or slop that's when the points are gapped at 0.015 so the 0.015 is merely an approximation. Perfectionists would set them using the Edge Gap Method versus 0.015 using a feeler gauge. If the edge gap is used and the points physical gap is at least 0.012 that's workable but if it gets much less then the points rubbing edge (that rides on cam) is worn excessive (or bushings are bad etc) and the points need replaced.

As Bob noted if the points are worn the same on both surfaces (no hill on one side and valley on other) that's a good indication the condenser is the correct rating.

John T
 
I can ONLY explain it for a Wico X Mag. Regardless in any mag the coil current peaks just as the magnet portion of the rotor exits the armature/laminations. In the Wico X you rotate the magnet/rotor until the magnet is just 0.090 (No 9 wire) out of the laminations. Then you adjust the points gap so it just breaks continuity at that location. The setting on them of a 0.015 gap approximates when that happens and is close and good enough generally but a perfectionist like my late departed friend Duane Larson (was a nuclear physicist) would use the edge gap method. The JD and Wico manuals explain this in detail. Best I have to offer for now, hope it helps explain the theory as you want to impart the maximum energy into the coil when the field collapses and that's when current is at its max so that's when you want the points to open.

Edge Gap Method

John T
 
are you supposed to somehow set time so that it fires (POINT STARTING TO OPEN) when roto button pointer starts to leave no. 1 cylinder terminal in distributor cap,rememerng spring release in mag.
 
Retard the timing all the way. (Rotate top of mag TOWARDS engine.)

Rotate the crankshaft so #1 piston is at TDC of the power stroke, and make sure timing marks at flywheel line up.

Then, slowly and carefully rotate the mag top AWAY from the engine block until the impulse trips, and lock it in that position.

Rotate the crankshaft two turns and slowly bring it up to the timing mark again, to verify how close the timing is. Make a small adjustment, if needed, and check again.
 
Walter, Im afraid you're confusing my description of the "Edge Gap Method" of setting the points (more precise then just use the feeler gauge method) versus general mag ignition start/impulse timing. The edge gap involvers the magnetic rotor and when it leaves the laminated armature, that's NOT the same as the rotor tip and the caps pickup terminals.

A Bob correctly told you with a mag the initial static start impulse timing needs to be set so it fires at the pistons TDC and that can be accomplished as he told you.

HOWWEVER that's NOT the same as setting the points gap (with edge gap or feeler gauge). Of course, she fires just as they begin to break open so their gap affects that, but the gap is first set (edge gap or feeler gauge) and then you set the initial static start impulse timing so the impulse trips and the mag fires right when the piston is at TDC. The edge gap insures maximum spark energy.

YES in general terms the coil fires when the points just break open and obviously at that time the rotor tip needs to line up with the caps internal pick up.

Got it????????? Hope this helps

John T
 
Hello again. Had mag apart and did not mark the gears that could be anywhere. Put in new wire that went from condenser to points. Insulation was bad and grounding out. Have back together with new points,condenser,cap,and new 12 volt coil (1.5)with new in line resistor. Still have a weak spark.I set the points on the peak of cam at 13 for the mag distributor. When you rotate the engine the pointer in the mag assembly or distributor lines up to the #1terminal the 12volt bulb I installed lights up and then the impulse trips sending the rotor button a little more going clockwise direction past the #1 terminal. Should this fire? Hope I am on right stroke and at top dead center. Can't find mark on flywheel. Had starter out and spent 2 hours turning it around with screwdriver and could not see the mark. Indeed it was an invisible man. I then put finger in #1 and turned motor with hand crank and felt air come out. I then put straw in sparkplug hole and turned fan blade till piston was on top dead center or as close as I could get it. Could tell this by the plastic straw going up or down. Thought it might be fuel issue for tractor has been out in rain,so I sprayed starter fluid in air cleaner intake and it did not fire. Do you think my timing is off? What else could it be? Checked for bad ground with multi meter and that seems to be OK. I have battery wire going to the post side of coil and negative going to resistor and then to the points. The condenser came out of a new 12 volt set of points that was for the distributer system. I have a new one that is for the mag system that I could use or try. Help
 
First of all, check the timing of the rotor gears, they ARE factory-marked.

Info is on 51 and 52.

http://www.cleancomputes.com/Cub/Blue%20Ribbon%20Service%20Manuals/GSS-5035%20Service%20Manual%20Magnetos/index.html
Timing the rotor gears
 
are the timing marks on mag gears easy to see? I could not find the timing mark on flywheel. Have read others have had the same problem. What is the relationship between roto tip and #1cap terminal,and top dead center;and the impulse release? Do the marks account for this release so when it goes together the pointer (distribution terminal vs.roto pointer) do not line up? Or do they line up. Trying to find timing mark on flywheel is like seeing a nat on an elaphant. It is there,but I can't see it. I might see a fly on a dianasour.Have a good day! Walter
 
I shouldn't respond as Im not exactly sure what you're using, I suspect Bob is better then myself on this question.

Im "guessing" youre using an external stand alone battery powered coil on a magneto and only using the mags set of points to make and break coil current, is that right????????????????

1) The coil should be wired to match battery polarity, that means if your at Pos ground the coils - gets ignition switched voltage when ON while its + wires to points. If at neg ground just the opposite.

2) On a mag points, they break open when the impulse trips/snaps.

3) If you turn on ign switch there should be voltage on the coils input (from battery NOT to points). When points are open (usually after she impulses) there should be voltage on coils output to points. When points are closed (before impulse) theres no voltage on coils output as its grounded via points.

4) When No 1 piston is at TDC on its compression power stroke if timed right the caps rotor tip is near the No 1 cylinder pickup and the mag is timed/rotated so she snaps right at TDC and she fires cuz the points break open at that time.

Best I have to offer as Im not sure what youre using

SEE WHAT BOB HAS TO SAY as I dont know what youre doing for sure

Sorry, John T
 
Did you go to the link I posted to the IH factory mag service manual and look a the photo of the rotor drive gears and timing marks?

NO need to overthink this, just line up the marks and put the little cover on with the two screws over the gears and you are done.

(The tip of the rotor will be stopped "ahead" of the #1 high-tension terminal in the cap as the impulse is winding up, then when the impulse "snaps" spark occurs more or less as the tip of the rotor is sweeping past the terminal, then immediately after spark occurs the rotor will have jumped quite a bit past the #1 high-tension terminal... it will never be lined up with the terminal unless it has been turned backwards.)

<img src = "http://www.cleancomputes.com/Cub/Blue%20Ribbon%20Service%20Manuals/GSS-5035%20Service%20Manual%20Magnetos/Page%2051.jpg">
 
lined up timing marks(in mag) and rotor tip is way before #1 terminal and still wont fire. Moved rotor clockwise and still won't fire. Will move it some more tomorrow. Maybe something else is wrong. Any suggestions?
 
Could be a bad or shorted coil. Find an experienced well recommended Mag repairman. They usually overhaul one in around an hour, and that includes diagnostics on the bench.
The only place I can personally recommend is AEI in OKC.
 
NO reason to muck around after I posted the link to the mag manual.

Set the the gears that drive the rotor to the timing marks and move on.

Since there is an external coil powered by the battery, it is now a "Kettering" ignition system, and needs to be troubleshooted as such, vs. a magneto.

This link MAY be of help to you.

http://www.cleancomputes.com/Cub/Blue%20Ribbon%20Service%20Manuals/FOS-20%20Chapter%206-Ignition%20Circuits/index.html
 
On some mags Im familiar with, BEFORE the impulse trips the rotor is BEFORE the pickup and of course AFTER the impulse its PAST the pickup. Its NOT right on the pickup, it passes by it when she impulses.

There cant be any shorting of the points (where condenser and coil primary wire attaches) as that kills the spark.

If its still a magneto the points open when she impulses and the induced current flows thereby creating a HV spark

If its a modified battery powered coil ignition, points still open to interrupt coil current flow via battery to points to ground (when closed)

Bob is giving you the details and mag info and Im laying theory on you as I dont know what mag or mod you have, hopefully you can figure it out.

John T Best we can do not being there
 
I have a new 1.5 coil,new in line resistor,new points and condensor,points set at 13 k,new coil wire,new wire 12guage that runs from condensor to points in the mag and a new cap. Have taken off valve cover to verify top dead center on no.1. I have lined up gears with marks and the rotor pointer is far away from no.1 terminal in cap. I have tryed to time by moving the gears one by one in the mag,and it still won't fire. The spark on plug does not look the greatest, for I would say it is a dim spark. Thought it might be fuel issue,so have used starting fluid sprayed in air cleaner and still won't fire. I am getting discusted. Are there any suggestions? Walter
 
WHY do you not believe the timing marks on the rotor drive gears, and continue to muck with the timing, setting it away from the marks?
 
Got farm all to fire and run. Worked some more on timing gears. Also had to blow jet out in carb. Also, the throttle linkage that runs to the governor has no affect on throttle speed. Something is broke or come loose inside of governor. Is there a way to fix existing governor or get another?This could have been part of original problem of it not wanting to fire. Walter
 
Not sure what you are working on, but it has the symptoms of a broken or unhooked governor spring.
 
Governor housing has to come off of front of engine.

It's been a long time since I've done one and I don't remember how tough it is to get it out past radiator and shroud.

Keep the weights and mag drive in place in the engine, or you will have to time them back to the camshaft gear.

The spring is Key #20.

Often, the thrust bearing, Key # 30 will be shot, as well.


<img src = "http://cnh-b2b.ptcmanaged.com/index.php/sbsimage/CSIH/default/1288729.png">
 
How does governor housing come off or separate it from mag pinion gear and weights,#28,27, so that pinion does not try to come off with the governor housing? If it did come off, how would you retime it??? Looking at diagram, looks like it will try to come out with the total housing or in other words, all in one piece. Walter
 
Governor and mag drive run in a large bushing in the engine block and can stay in place in that bushing while the housing is removed, keeping the gears meshed.

If the gears DO get out of time, the cam and governor gears have timing marks to match up.
 
Does key 29 thrust sleeve come off with the governor housing? Is there a kit for the governor ? Does the governor weight pin stay on the engine?
 

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