Timing

[Steve M]

I have a 1939 Allis Chalmers Model B. I've seen timing lights that attached to the car battery. Since I don't have a battery, is there a special timing light I need?

 

[edj856]

You can get a battery operated one or one that hooks up to a car battery, you'll just need to have a battery sitting next to the tractor while timing it. The battery only provides power to make the strobe flash, the timing of the flash is still through the spark plug wire.

 

[huntingreen]

I have never been able to set the timing on a tractor with one of those timing lights. Just tried a Farmall M a couple weeks age. Using the light it was way out of time. Took # 1 plug out with # 1 piston up on compression stroke, removed #1 plug and rotated the distributor until it sparked. Tractor ran a lot better this way. Tried the timing light on a couple JD H tractors and did not have any luck there either.

 

[Bob]

Since this is a "mag", the initial (impulse) timing must be very close to TDC, and NOT before, or it will "kick" and break your arm. That is the IMPORTANT timing setting.

ASSUMING you have the correct mag, (with the correct "impulse lag angle"), as soon as the engine "catches" and begins to rev up, the impulse "drops out", and the timing instantly advances to the full running timing.

If the mag has been "bench tested", verifying the correct "lag angle", and you set the impulse timing to TDC, all will be well.

To make any significant changes, the mag's "impulse lag angle" will have to be changed.

 

[deadeye012]

Most timing lights that you buy today are of the 12 volt varity. So you need a 12 volt battery to hook it to although you can still find a few 6 volt units around...JB