Homemade 7 HP Economy

| June/July 1991

  • 7 HP Economy Engine

  • 7 HP Economy Engine

1222 Deep Creek Road Manhattan, Kansas 66502

A little story about a repowered B John Deere-I had an old 7 HP Economy which was in bad shape. The cylinder was rusted and pitted very badly, no mag of any kind other than it was all there. I cleaned it all up, put some rings in it, and installed a Wico trip mag. I made the trip assembly plate to go where the ignitor originally was. I had to make a gas tank as the old one was rusted away. Anyway, I got it running and it ran okay, some blow-by, but not that bad.

I had been thinking about putting this engine in an old farm tractor, for some time. I decided to use a John Deere B, as I could belt to the flywheel and have the clutch, belt pulley, and transmission work like it always did.

I got a 1941 John Deere B and started to work. I removed the head and block assembly, fan drive, radiator, governor and mag housing. Removed pistons and rod. I plugged oil holes in rod journals as I needed to keep the oil pump to feed main bearings, cam and oil pump drive. (Didn't need cam but it drives the oil pump). Made a plate to cover the front of the crankcase. Also made a cover over top of the cam gear and plate cover on top of the pump drive. I installed a pressure gauge here, as it would have pressure like always.

This was a long frame B (maybe all the later ones were?), but I still had to lengthen the frame eight inches. I cut the bottom angles out of the frame to set the Economy as low as I could since the engine is very heavy. I made hangers to set the engine on, and they are 6' below the bottom of the tractor frame.

Now, to belt up. I didn't want to run a twisted belt, so I decided to change the rotation on the engine. This was easy because the cam bob was riveted to the cam gear. Next, I removed the rivets, turned the bob over, re-riveted it and retimed the gear. It starts easy and runs good but it's terribly out of balance. At about 250 r.p.m. it bounces the tractor bad, but above or below 250 it's not as bad. When it's moving you don't notice it much. The engine was designed to run one way and when you reverse it, the torque and thrust change. Someone told me to cut new keyways in the crank and change the flywheels 180 degrees. Personally, I don't buy that, but I may be wrong. I haven't and probably won't do this. Anyone who can shed some light on this, I would like to know their view.


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