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More Mag Questions


 
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zf3434
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Joined: 01 May 2021
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PostPosted: Sat May 08, 2021 8:09 am    Post subject: More Mag Questions Reply to specific post Reply with quote

Thanks to everyone who helped me with my last post on the Wico X. I cleaned on the points again this morning and I have a big fat blue spark now!

However, got a question about installation. It is going on an H. I found some instructions on the net and tried to follow them the best I could. I brought LH side up to TDC and aligned the dot on the fly wheel with timing mark. I then installed the mag hand tight and moved it all the way forward. I then rolled the engine over until LH TDC dot aligned with the flywheel again (on the compression stroke). I am then suppose to rotate the mag backwards until it snaps and tighten. But it never snaps. If I move it all the way back and tighten it will snap just after the mark hits. About a half inch or so past the mark.

I did check with the plug out and it fires the LH side when the dot is just past the mark.

What am I doing wrong? Also, I don't have a gasket for the mag. Do I need to get one or will it be alright without one?
 
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Mike(NEOhio)
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Location: Geauga County, Ohio

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PostPosted: Sat May 08, 2021 8:35 am    Post subject: Re: More Mag Questions Reply to specific post Reply with quote

When you positioned on LH TDC did you check that the mag drive slots were horizontal? If not your cam is out of time. And when you put the mag back on be sure the
impulse coupling is engaged.
 
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zf3434
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PostPosted: Sat May 08, 2021 9:15 am    Post subject: Re: More Mag Questions Reply to specific post Reply with quote


Yes, they were horizontal.
 
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John T
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PostPosted: Sat May 08, 2021 9:28 am    Post subject: Re: More Mag Questions Reply to specific post Reply with quote

Iffffffffff the flywheels on the correct crank spline and ifffffffff the crank to cam and cam to governor shaft are all in
time ??????????? when the Flywheels LHI (TDC of cylinder) is flat at 3 o clock with the mark the female drive slot in the
end of governor shaft (where mags coupler fits into) should be flat horizontal fore n aft. Then you can either or both turn
flywheel a bit backwards and/or have the mag rotated forward CW (retarded) to where the drive cup mates into the governor
shaft end slot. Then get the mag in and then turn flywheel forward to LHI at 3 o clock, then slowlyyyyyyyy advance mag
timing backwards CCW till the impulse snaps WILL GET YOU CLOSE TO THE INITIAL STATICE START/IMPULSE TIMING...... Once i n
you can tweak the start/impulse timing (turn mag forward CW to retard back CCW to advance) until she snaps right when
flywheels LHI passes flat 3 o clock mark. Too fast flywheel may kick back too sLOW harder to start. You have to have the
mags coupler turned to where shes ready to start the wind up n trip when you inserts it as described above AND IN THE SLOT

Some guys have pasted the page out of JD manual that shows this

John T
 
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Loosehandle
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PostPosted: Sat May 08, 2021 11:42 am    Post subject: Re: More Mag Questions Reply to specific post Reply with quote

I'd probably just try to start it at
this point, it ain't the space
shuttle...
 
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dan_41jdh
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PostPosted: Sat May 08, 2021 12:33 pm    Post subject: Re: More Mag Questions Reply to specific post Reply with quote

IF the slots of the magneto drive coupling are horizontal when the LH Impulse mark on the flywheel is at the 3 oclock position and aligned with the timing mark on the gear case cover, and IF the magneto must be rotated all the way to the rear in order to make the magneto snap at (or slightly after) the correct flywheel position during cranking, perhaps the impulse stop of the magneto is set incorrectly.

This illustration shows the approximate position of the witness mark on the impulse stop for the 25 degree drive cup (#6274) and the 35 degree drive cup (#3565). Its shown on the 4th mark left of center, but should be closer to the 4-1/2 marks left of center. The witness mark should be 3-1/2 marks to the left of the center mark if you have a 30 degree drive cup (#2061B).

Regardless, the witness mark should never need to be beyond the 4-1/2 marks left of center shown in the illustration.



 
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John T
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PostPosted: Sun May 09, 2021 3:10 am    Post subject: Re: More Mag Questions Reply to specific post Reply with quote

Yo Dan, I think we had this discussion before ??? Based on ONLY memory so may not be right grrrrrrrrrrr I thought for ALL drive cups OTHER THEN the 6274 (which is a 25 degree) the top center index mark represents 0 degrees of lag,, but when using the 6274, top center = 12 1/2 degrees of lag

THEREFORE to set the lag angle when using a 6274 to get the 25 degrees it would be set 2 1/2 to left as 12 1/2 + 5 + 5 + 2 1/2 = 25 NOTTTTTTTTTTT 4 1/2

If using say a NON 6274 25 degree cup, THEN it would be set 4 1/2 to left as 0 + 5 + 5 + 5 + 5 + 2 1/2 = 25

HOWEVER I can see where I may be wrong since for a 35 it would be too far left ????? I THINK I'M WRONG GRRRRRRRR HELP ME OUT HERE

What say you my friend

John T
 
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miangus
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PostPosted: Sun May 09, 2021 9:17 am    Post subject: Re: More Mag Questions Reply to specific post Reply with quote

Roll it over two complete revolutions and listen for the snap, if it doesnt snap somethings wrong with the mag or drive lug.
 
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dan_41jdh
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PostPosted: Sun May 09, 2021 12:48 pm    Post subject: Re: More Mag Questions Reply to specific post Reply with quote

Rotating the witness mark of the impulse stop ring to the center timing mark represents a 12-1/2 degree lag angle for both the 3565 cup (35 degrees) and the 2061B cup (30 degrees). And since each timing mark represents 5 degrees of change, you would (nominally) set the witness mark 4-1/2 marks to the left for the 35 degree cup and 3-1/2 marks to the left for the 30 degree cup. (12.5 + [4.5 x 5] = 35, and 12.5 + [3.5 x 5] = 30). However, that center timing mark represents a 2-1/2 degree lag angle for the 6274 (25 degree) cup. In that case, you would set the witness mark 4-1/2 marks to the left (2.5 + [4.5 x 5] = 25).

Regardless, those are nominal settings which should be verified and fine-tuned on a magneto test stand.

Our late friend Duane Larson described an excellent procedure for setting the timing of a magneto-equipped Deere by first setting the run timing using a timing light against a degree-marked flywheel and then adjusting the impulse stop ring to the proper position to cause the impulse to trip just at or slightly after TDC.

Make sense or still clear as mud?
 
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John T
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PostPosted: Sun May 09, 2021 2:02 pm    Post subject: Re: More Mag Questions Reply to specific post Reply with quote

Im still cornfused about the top as 12 1/2 or 0 or whatever lol for what cups Im gonna have to study up on all this I used to know it perfect but my old hard drive is full lol

Duane and I were good friends and gave a few seminars together years ago

Thanks for your help hope to meet up again sometime, come on down to Florida some winter

John T
 
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dan_41jdh
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PostPosted: Mon May 10, 2021 4:56 am    Post subject: Re: More Mag Questions Reply to specific post Reply with quote

Well, my hard drive isnt quite full yet, but getting access to the info becomes increasingly more difficult as time goes by, haha.

Anyway, here are excerpts from the WICO C and X service manuals. The C manual does state that the center mark is 13 degrees (I'm gonna call it 12-1/2 degrees because the math is cleaner). I suspect the 6274 cup (25 degree) came out when the X was launched around 1946 (adapted by Deere in late 1947), around when the X became the designated replacement magneto to replace the C. And the X manual does state that with the 6274 cup, the center mark is 3 degrees (I'm gonna call it 2-1/2 degrees).

Deere Field Service Bulletin 159-S describes a simplified replacement program where the new X, which was furnished with the 6274 cup as P/N AA3870R, could replace virtually any flange-mounted magneto for Deere tractors since it could be adjusted for a standard 25 degree lag, or a 30 degree lag. And by substituting a 3565 cup (35 degree), you could get a 35 degree lag. So with one magneto and two interchangeable cups, you could get 25, 30, or 35 degree lag angles.

I'm certainly not a magneto expert and I don't know why the center mark of a C magneto with the 6274 cup is 3 degrees. It may have to do with the design of the impulse stop ring of the C. I haven't examined a C to determine any differences compared with an X, but I do know that the only difference between a 2061B cup and a 6274 cup is the location of the edge of the slot contacted by the drive flange during running is different by 5 degrees, which makes sense as the 6274 is a 25 degree cup and the 2061B is a 30 degree cup. However, the other edge of the slot (the one that pushes the trip arm off the impulse stop) is in the same location on both cups. This makes me wonder if there is a difference in location of the stops between impulse stop rings on the C and X.


 
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zf3434
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PostPosted: Mon May 10, 2021 6:48 am    Post subject: Re: More Mag Questions Reply to specific post Reply with quote


Wow, thanks everyone for the wealth of knowledge. I'm away from home for a couple of days but I will look at the witness mark and maybe take a couple of pictures when I get back.

The mag snaps well and I have a big blue spark when it was on the bench. After I posted, I tried to start it. It did run but I really feel the timing was off. It was struggling and backfired a few times.
 
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zf3434
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PostPosted: Wed May 12, 2021 5:01 am    Post subject: Re: More Mag Questions Reply to specific post Reply with quote

I had five minutes last night to pull off the mag and the witness mark is on the first notch from the left. From what I understand it needs to be on the second notch or 4th from the center, right?

Do I loosen the two screws and move it or what is the procedure to change it correctly?
 
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