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Tecumseh Carburetor Replacement

Article by Mark Trotta

The original carburetor was missing off this Tecumseh H25 motor, so I needed to find a suitable replacement. Many of the old, original part numbers have been changed or superseded by Tecumseh. Fortunately, most have only minor differences, so with a little homework you should be able find one that will work correctly.

tecumseh flathead carburetor

There are several types of carburetors for Tecumseh flathead engines. Some will have chokes, and some will have an idle adjustment screw. Smaller horsepower engines (Tecumseh H25, H30, H35) may have neither of these.

Finding A Replacement Carb

The first replacement carb I bought had a priming bulb, no choke, and was non-adjustable. It fit correctly but the motor wouldn't start. The primer bulb was working, as gas was getting into the float bowl, but it just wouldn't start the motor.

After looking online for a solution, I found a forum member with the same problem. He remedied his situation by switching to a carburetor with a choke.

Choke Carburetor

The second carb was purchased from the Rop Shop on Amazon. It replaces original equipment carburetor numbers 631921, 632284, and 631070A, which are commonly found on Tecumseh H25, H30, and H35 engines.

New Carb for Tecumseh 631921 632284 631070A fits H25 H30 H35 engines

Shop: Tecumseh Flathead Carburetor

Applications include many Tecumseh-equipped snowblowers, which operate in cold climates and need a choke to help it start. It also fits many Troy-bilt rototillers.

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Air Cleaner

All gas engines need some type of air filter to keep dirt out of the carburetor, and small engines are no different. With the exception of initial break-in and troubleshooting, you should always run your engine with an air filter.

replacement carburetor for Tecumseh flathead

I was missing the stock air filter, so I bought a high-flow air filter from Amazon.

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Should I Remove The Governor?

Most vintage Tecumseh engines have a mechanically-activated governor. This is controlled by a rod that passes through the aluminum case, and an arm connected to the carburetor with a long spring.

The governor is designed to do two things. First, it helps maintain a constant engine load, but it also limits maximum engine speed, which protects the engine from possible damage.

Tecumseh carb replacement for H25 H30 H35 engines

Should you remove the governor on your kart motor? If you're not racing your kart, I would recommend leaving it in place.

Check that the rod is not binding and the governor spring is not overly stretched. A deformed spring will affect governor operation and should be replaced.

Tecumseh flathead governor installation

To adjust governor for best operation, perform the following:

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Related Articles:

Vintage Tecumseh Engine Identification
Tecumseh Engine Rebuild
Tecumseh Crank and Connecting Rod Inspection
Tecumseh Points Ignition Repair