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Motor Swap - 15.5--16 or 17hp

6141 Views 5 Replies 5 Participants Last post by  Ferstlerslim
I have a Dynamark(Murray) mower with a 15.5hp Tecumseh OHV engine. It is in great shape but has a blown motor. It was run dry of oil and i believe it snapped the connecting rod.

I want to put another motor on it. So my question is do Briggs and Stratton have the same bolt pattern for mounting as Tecumseh and how many shaft length/diameter variants are there in the 15hp - 17hp range? Or are they all pretty similar?

Thanks so much for the help, i'm a newbie here so i appreciate it.

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This may be of no help but in my 87 Lawn Chief, I went from a 12HP Briggs to a 18HP opposed twin Briggs and the main shaft and mounting bosses were the same. Well the mounting bosses might not have been the same but I do remember that my engine fit in place of the original with no drilling necesary. Not sure if the frame on my tractor had dual mounting bosses or if the bolt pattern was the same but I'm pretty sure that the bolt pattern was the same. But this is all with flat head engines, not the modern overhead valve engines.
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Any Tecumseh or Briggs single should mount up pretty much without modification to the frame or drive. Now, the wiring, controls, and muffler may be different, but these are minor.

Both and have "technical info" on their websites where you look up engines,that show you the mounting bolt patterns and physical dimensions,etc..makes comparing what will swap on an older machine a lot simpler!..
I've done a few swaps and find that they all had multiple patterns in the engine mounting plate. I took a 20 hp Kohler single out of an 07 Husqvarna and dropped in an 18 horse Briggs twin. Everything bolted right up, shaft size was the same. Wiring was totally different and I ended up with a kill button and a mower that now mows backing up and keeps running when I get off. Also had to work on the cables a bit.
I also put a Briggs twin into a 11 JD, had to do some body mods but it bolted right in and the shaft was the same.
I love those twins, so much smoother than singles.
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Great info, thanks for the help!

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