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Magneto Timing Tips

Here's a few tips on timing that ole magneto to your engine. We'll be adding more in the future so if you don't see what you need here now keep checking back or e-mail us and ask.

   John Deere B Timing tips Click Here.


John Deere "E" Engine

   Match the timing mark on the camshaft gear with the mark on the magneto gear. Make sure the igniter is timed properly then press the timing rivet marked “L” on the magneto while the flywheel is turned and the rivet should drop into the notch and start out just as the igniter trips. If necessary adjust the trip finger slightly until it trips exactly at this time.


Timing Magneto with Impulse Coupling by Coupling Release

Where timing mark on flywheel of the engine is not accessible, making it difficult to determine the exact position of the piston, the magneto may be timed to the engine by the release position of the impulse coupling. The procedure is the same for both fixed and timing range magnetos.

Determine the release position of the impulse coupling and place a mark on both the arrester plate and coupling housing to indicate this position.

Install Magneto on Engine.

Rotate the impulse coupling in the OPPOSITE direction the magneto is to be driven until marks on both the arrestor plate and coupling housing coincide. check to be absolutely sure that the arrow on the distributor rotor points to the cable outlet, or tower, No. 1.

Time the engine so that cylinder number 1 is slightly beyond top dead center making certain the piston has definitely started downward on the power stroke.

Connect magneto drive to engine.

Complete the installation by connecting the cables of the magneto to the spark plugs in their proper firing order, (usually marked on the engine block). The firing sequence of the distributor plate towers is opposite the direction the magneto is driven. When facing the distributor plate the cable outlet tower No. 1 is always located in the upper right hand corner.


Timing Magneto to Engine:
Fairbanks FM 4

Where specific instructions are given by the engine manufacturer, it is recommended that they be followed in preference to those herein given.

How to time the engine:

Rotate the engine flywheel until the piston on # 1 cylinder, [ this is usually the closest to the radiator ], is in the firing position of the compression stroke. The flywheel is usually marked to identify this position. Another way is to put your thumb over, NOT INTO, the number one plug hole and rotate the engine until you feel or hear the compression. Next you need to know the piston is all the way up to the top. You can judge this by the marks on the flywheel or insert a rubber hose into the cylinder to judge the piston’s height within the cylinder. Do NOT turn the engine with the hose inserted!

Time the Magneto to the Engine:

Rotate the magnetic rotor in the opposite direction of rotation, as indicated by the arrow on the magneto mounting plate, until the “White Line” on the distributor gear is visible through the “observation window”. With the “White Line” visible in the observation window connect the magneto to the engine, moving the coupling of the magneto slightly, as required, in order to line up the coupling drive of the engine. Fasten the magneto to the engine. Both the engine and the magneto are now in the correct firing position and the first magneto spark will be received from the upper left hand terminal tower which is to be connected to the spark plug on the number 1 cylinder, which is the one closest to the radiator. Complete the installation by connecting the remaining spark plug cables in the proper firing order, usually marked on the engine block. The firing sequence of the distributor cap is in the opposite direction of the magneto rotation as indicated by the arrow on the magneto housing and must be taken into account when connecting the spark plug cables to the magneto.

Note: If viewing from the drive end the magneto rotates clockwise then viewing from the cap end the rotation is clockwise as well but is actually turning in the opposite direction.


John Deere "LA" Magneto to the Engine by Jeff:

   I had a lot of trouble finding the instructions or information on the web about timing LAs. Everyone seems to work on the Bs. I found an email in a help forum that dated back to 2002, where some guy was asking for help timing an LA. The person that wrote a helpful response back mentioned that he had the instructions. So I shot him an email and he responded with the instructions.
   I was pretty much correct with what I had figured out prior to the instructions. I just did not want to risk timing it incorrectly.
   You do have to get past the impulse and then rotate back to the point where the points just start to open. This should occur when the "SPARK" mark on the flywheel lines up with the DC mark in the window. I used a .0015 inch feeler gage between the points to tell for sure when they started to open. I rotated the mag until the points just started to let go of the feeler gage, and then gave it a little extra nudge to make up for the thickness of the feeler gage.


Belanger's Auto Electric
127 Cyr Road
Cross Lake, Maine 04779
Phone: 207-834-7309

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