John Deere La mag timing help.

golfcartman · Jun 17, 2019

Need a little help timing an LA. Put new rings in but did not remove crank or mess with the engine timing so all I need is help timing the mag. Had flywheel off but it will only go on one way so that should be correct. Can't get the mag to fire when the flywheel shows spark in the viewing hole. My book shows the position of the rotor on the mag but it looks like a wico c, I have a wico x. Not sure if they will be the same or not. Thanks for your help

Mike M · Jun 17, 2019

IIRC that spark mark lined up in the center of the window would be for running timing using a timing light.
For non running or starting timing the TDC mark should be at the bottom edge of the window hole when the mag. impulse trips. This is so it fires at just past TDC and does not kick back while hand cranking.

John T · Jun 17, 2019

I'm with Mike as far as initial static start timing goes. The mag has to impulse/snap just when the piston is at TDC, if too soon it kicks back if too late harder to start. On the X mag with the two tip rotor the leading tip has to pass by and fire number one (its internal cap pickup) on TDC and then 180 later it fires number two on its TDC with the lagging rotor tip...?

This is for static start timing NOT run timing...

I'm more familiar with the two banger tractors and not much the L's so don't take too much of what I said as gospel lol

John T

golfcartman · Jun 17, 2019

This mag is a single tip rotor not the double.

teddy52food · Jun 17, 2019

I rebuilt an LUC engine & didn't have a mag for it. Found a gear on E bay & fitted it to a FM v4 wis mag. Grounded 2 wires to a spark plug & fire with the other 2. As I crank I can watch it fire the outside plug. Gear is a slant cut so I could fine tune the timing by shims at the gasket. Fires just after tdc & has more advance than the mag that belongs on it.

John T · Jun 18, 2019

Some had single tip other the double, thanks for the feedback. In that case when No 1 piston is at TDC the single rotor tip should be closely aligned with the inner cap pickup terminal that fires the No 1 spark plug. On the two banger tractors with a Wico C or X if the mag was installed 180 out a simple plug wire reversal got them going.

John T

John Deere La mag timing help.

golfcartman

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Mike M

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John T

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teddy52food

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