Articles By Tractor Brand Farmall and International Harvester Uncategorized

How to Increase the Horse Power in your Farmall M

Everybody wants more power out of their tractor, right? I’ll share my best tips for increasing the HP on your Farmall M.

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The following are some affordable ways to gain more HP:

  1. Install a power valve inside the carburetor. Consider using a power valve from either a Farmall 400 or 450 to make your carburetor larger jetted. A power valve can be purchased at your local CaseIH dealership.
  2. Increase your compression ratio by installing a set of pop-up pistons. If you are mechanically inclined, you could easily install a pop-up piston kit on your own.
  3. Increase your bore from 3 7/8” to 4 1/8” (if you choose to install pop-up pistons you could do both step number 2 and 3 at the same time).
  4. Make sure your tractor has a good head, and consider upgrading it. The best head is an LP Gas head. They have bigger valves which gives higher compression and better flow resulting in a significant improvement. However, they are expensive. If you can’t afford an LP gas head, at least make sure you have a gas head instead of a kerosene head. If your tractor serial number ends with X1, you likely have a gas head (unless it’s been changed through the years). If your tag ends with X3, you likely have a kerosene head. If you discover a kerosene head on your tractor, remove it, and replace it with a gas head (good) or LP gas head (best).
  5. Install a better camshaft, like one made by Denny’s Carb Shack or Iseki.
  6. Obtain better fuel flow by installing a LP Gas intake and exhaust manifold. The manifold easily attaches onto the block with the same bolts and holes.
  7. Install a rocket governor. You may be able to find a used original governor made by M&W, but if you can’t, several places are making and selling new high performance governors.


If you have deep pockets, try these upgrades for a more significant HP gain:

  1. Increase the stroke with a custom crank and rods. This is expensive, but if you’re serious about tractor pulling and want to win every time, it may be necessary.
  2. Install roller rockers! A set of new rockers will change the duration of how fast the rockers open and close–which enables your engine to move more gas in and out.


The Farmall M at my house has M&W power pistons, a M&W rocket governor, improved camshaft, 450 carburetor jets and a LP-gas intake and exhaust manifold. With these affordable upgrades, the tractor is somewhat competitive in the 5500+ pound class and has brought home several trophies. While competing is fun, building the tractor is the best part for me. Have fun making these improvements to your Farmall M tractor!


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2 comments on “How to Increase the Horse Power in your Farmall M

  1. Is there any where to get “rocket” governors for a deering 10-20 or 15-30? over here in the uk theres not many 10-20s which were brought in during ww2, and its even more difficult to get parts.!


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