timing john deere A

[cbd]

Good morning all.Can anyone explain how to
set timing on a 1944 john deere A.It has the
big fly wheel that you turn to start no battery
Or electrical.It will only start when pulled.
but sounds like timing is off.Thanks for any
suggestions.cbd

 

[F-I-T]

When you turn the flywheel over slowly, the magneto should click or snap. This is caused by the internal impulse spring tripping. The spring allows the mag to flip very quickly to generate the spark during cranking speeds, when your arms can't turn the engine over fast enough to generate a healthy spark. Many times these springs break, and the tractor will only start when pulled, because pulling spins the engine fast enough to spin the mag fast enough to generate the spark.

So, does it "snap" when you turn it over? If not, start there. If it does, then we can talk timing. Does it run well once started? BTW, you can use a timing light to set the running timing, but you also need to have to secondary timing (lag angle) set properly which is used during the cranking time.

 

[John T]

Good advice from the Frankster, so if or once the Mag makes a loud sharp SNAP when shes hand cranked (EVERY 180 OF FLYWHEEL REVOLUTIONS IF A DIRECT DRIVE MAG), we can advise you about setting the initial static start timing and the run time advance.

Once shes snapping/impulsing the initial static start timing is set so that snap occurs right when the Flywheels Left Hand Impulse (LHI) timing mark is at the flat mark on the tractors side located at the 3 o clock position. If too fast the flywheel kicks back if too late shes harder to start. That mark is right by the flywheels outer circumference towards the rear (away from engine) ON THE TRACTORS SIDE.

Let us know what mag you have also.

The run time advance (once shes over 250 RPM) is mostly a function of which drive cup your mag has, such as a 25 or 30 or 35 degree advance, followed by the mags rotational adjustment in the govenor flange (forward CW retards, backwards CCW advances), the points gap, wear n tear n slop.

The only way to actually tell the run time advance is to use a timing light.

John T

 

[cbd]

thanks for the info. i have to find out about you guys questions.will post back later thanks
again.