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4100 repower


dmal195

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Hello I'm new to the forums but have been using Simplicity tractors for years. I have a question and I searched the forums for an answer and didn't find anything so I thought I would ask.

I have a 4118 that has had the motor swapped to a Briggs 16 hp that has now started using oil. I would like to repower the tractor with a 20 hp Briggs apposed twin that I have. Anyone done this before?

 

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Welcome.  A vertical shaft transplant is a lot easier than a horizontal shaft transplant.  I put an 11.5 HP single into a 707 and it bolted right up.  All I had to change was the exhaust, the depth of the drive pulley, the gas tank,  and I had to modify the hood.  You won't have to make a driveshaft adaptor and will probably get away without changing the frame-to-engine height.

See https://simpletractors.com/forums/topic/58559-115-pounds-of-potatoes-in-a-7-pound-sack/?tab=comments#comment-469125

Sounds like a fun gig.

 

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So it's been a long day and I just realized I had the model numbers mixed up and what I'm asking about is putting an apposed twin Briggs in a 7100 not a 3100

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Ok - now you'll have to make a flywheel adaptor and probably raise the engine.  You will have to find the original crank shaft center line to assure the new engine is properly aligned with the drive shaft.  I put an 18HP Vanguard in a 7119.  See if there is anything in my post you can use.  https://simpletractors.com/forums/topic/54692-7119-re-power-with-vanguard-350445/?tab=comments#comment-54695

You can also search the forums for "Vanguard transplant".  That is a more common repower but you can probably find some sound advice.

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The crank adapter doesn't scare me and raising the engine is not a problem. My concern is will the cylinders on the apposed twin clear the frame?

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Measure to the CENTER of the original crank shaft.  Since your machine did not have the original motor, you will have to include the height of any mounting plates that were used with the previous repower.  Measure to the center of the replacement motor.  The difference is how much you need to raise (or lower) the next engine.  Make a test fit with blocks of wood to see if the cylinders clear the frame.  If not, you can notch out the frame.  You can reinforce the frame below the notch if it makes you feel better, but that frame is pretty sturdy.

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