1946 John Deere B MAGNETO

Hello,

Purchased a rebuilt Wico C short lug magneto for the ole B. Followed the owners and I & T manuals and the tractor isnt starting. Have new spark plugs, spark and fuel but its not starting. Noticed the plug wires going into the mag seem loose and did push them in to ensure they were tight. Any way to tighten those (besides replacing them)? Any ideas on the issue?

Did this tractor run before you replaced the mag?

I think I have a magneto book I’ll check later

Have u confirmed that it has spark at TDC on #1 cylinder ? Is it getting gas into the cyl’s? Have u squirted some gas into the cyl’s and Tryed to start it? And if U have spark and fuel then it’s timing. We don’t have eyes and hands on the subject so a person needs exact explanations and steps of what u have done

Yes tractor ran before replacing the mag. The old mag was weak and backfiring, more so in recent time. Have not tried squirting gas in cylinders. It was getting fuel into cylinders at first believe is now also. I watched a video of a guy installing a mag on an unstyled B. Mine is early styled and electric start. It clicks but seems to click after the piston reaches TDC if that makes sense.

Like rustred mentioned it sounds like the timing is off. I would start there confirming that everything is set correctly.

I would suggest that you get a WICO X magneto. They are much more reliable.

Thank you all. I know diagnosing anything over the internet is tough, I deal with that every day at work. Will definitely get this running.

"[b:654c4848f0][i:654c4848f0]Any ideas on the issue?[/i:654c4848f0][/b:654c4848f0]"

Agree with others on timing issue.

You might consider checking the timing on the No. 1 (flywheel side) cylinder.

To prevent the tractor from accidentally starting:

Remove the spark plug cable from the No. 2 spark plug.



Make sure the gas is turned off.

Lock both brakes.

Transmission should be in neutral and the hand clutch should be disengaged.

This is one method of checking the timing.

Remove the No. 1 spark plug on the flywheel side.



Place your finger over the hole and rotate the flywheel in the running direction (counter-clockwise) until you feel pressure (compression) of air in the cylinder.

Continue rotating the flywheel counter-clockwise slowly until the “[b:654c4848f0][i:654c4848f0]L. H. IMPULSE[/i:654c4848f0][/b:654c4848f0]” mark on the flywheel lines up with the reference mark on the gear cover.



Loosen the two cap screws securing the magneto.

Tap the top of the magneto toward the rear of the tractor a little at a time until the impulse trips.



Tighten the cap screws and continue rotating the flywheel counter-clockwise until you see a spark at full pressure (compression) for No. 1 cylinder.



Hope this helps.

For good mag tractor starting, the initial start/impulse timing is critical. It needs to snap/impulse right at TDC, if before it kicks back if late its harder to start. I always first set the Lag Angle to match the drive cup used and then loosen the governor mount bolt so you can just turn the mag, turn the flywheel slowlyyyyyyyyyyy and adjust the mags rotational position so it SNAPS just as the LHI flywheel mark passes the flat timing mark at 3 o clock on side of tractor.

If you rotate it forward CW it retards the spark if backwards CCW it advances SET IT SO IT SNAPS RIGHT AT TDC

Is there a spark at both plugs ?? and is it snapping loud n sharp each 180 of flywheel rotation ?? If theres no mag spring winding n tripping SNAP (impulse assembly) she wont fire at cranking speeds.

John T

I agree with Slewfoot

Friend had a similar problem with his A. He had replaced the Mag, and reversed the spark plug wires.