How to Time a Farmall Tractor


Farmall tractors were introduced in 1924 by the International Harvester company and were produced until the mid-1970s. These tractors were a staple on American farms for many years, and as a testament to their longevity, a number of these models are still in operation. Farmall tractors use a magneto ignition, which supplies its own current and does not require a battery or generator. The magneto does need to be adjusted periodically to keep your Farmall ignition in time and your tractor running smoothly.

Things You'll Need

  • Spark plug wrench
  • Pull the cable out of the center position on the distributor by hand so as to avoid unintentional starting of the motor while timing the magneto.

  • Find the top dead center of the No. 1 cylinder as follows: Locate the No. 1 spark plug (located near the timing gear) and remove it with a spark plug wrench in a counter clockwise direction. Place your thumb securely over the spark plug hole. Place the tractor’s engine crank onto the crankshaft nut and turn the engine over by hand in a clockwise direction until a noticeable force is felt from the hole. Continue to rotate the crank slowly until the indentation on the fan pulley lines up with the timing mark on the crank cover. Remove the engine crank.

  • Remove the distributor cap by rotating the holding clips away from the cap by hand and lifting it off of the magneto.

  • Locate the magneto coupling on the bottom of the distributor cap and turn it in a counter clockwise direction by hand until the rotor points to the number one position on the cap.

  • Replace the distributor cap onto the magneto and rotate the holding clips by hand towards the cap to secure it.

  • Replace the cable in the center position on the distributor by pushing it firmly into place by hand.

Tips & Warnings

  • Some models of Farmall tractors have two indentations on the fan pulley. The second indentation indicates top dead center.
  • The magneto ignition produces its own current, therefore should never be connected to your Farmall’s electrical system.
  • The magneto is a mechanical device and makes an audible click when spark is generated. If your magneto does not click, the magneto may need to be replaced.

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  • Photo Credit Goodshoot/Goodshoot/Getty Images
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