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7 and 10hp aluminum Briggs engines

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Question - does anyone know dimensions of or interchangeability of the vertical crankshaft aluminum Briggs engines?  I know the 6 and 7hp engines (like in my early Broadmoor) are dimensionally the same.  I think an 8hp is also the same size for length, width and height.  What about a 10 or 12hp?  I don't have one of the 10/12 to measure, but have been offered a 4210 that supposedly ran.  I was thinking that the 10/12hp flatheads were physically a bit larger than the 6/7/8hp engines and it won't fit under the hood of my Broadmoor.  I am not going to hack a tractor to fit an engine.  Thanks, Tim

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As far as I know the 10 and 12 are the same for all practical purposes. I know I have swapped out several over the yrs with no fitment issues. 

Edited by fishnwiz

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The Simplicity 707 came from the factory with a 7 HP Briggs & Stratton 170702.  I bought mine with no motor at all so I installed an 8 HP 190705.  It dropped right in.  One day it tipped over and I never could get it running again so I installed an 11.5 HP 217807.  The footprint was a direct match but SEW says that,  "No other engine will fit in this frame because of the way the hood support bolts onto the head."  So I bypassed the hood support.   The only other mod I had to make was to bore out the pulley for proper belt alignment.  I've been wrong before but I'm guessing that most single cylinder vertical shaft engines will have the same mounting bolt pattern.

side ii.jpg

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23 hours ago, fishnwiz said:

As far as I know the 10 and 12 are the same for all practical purposes. I know I have swapped out several over the yrs with no fitment issues. 

Meaning they are the same as the 6/7/8hp, or the 10 and 12 are the same as each other?

I figured 10/12 was the same, but thought the overall dimensions were slightly bigger than the 6/7/8hp.  

Again, I am not interested in hacking or leaving parts off my old Broadmoors to put in a wrong engine.

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The 7, 8, 10, 11 and 12 (and probably many more) all have the same mounting bolt pattern. Even newer, larger OHC engines have the same mounting bolt pattern.. The 10 hp from 4210 is a little larger at the top flywheel cover, but just a little. On the later Broadmoors, it can be made to fit just by elongating the mounting bolt holes to move the engine forward a fraction but that may cause problems with the 2 belt drive pulley system used in the early tractors and would also likely cause slight misalignment with the grill mount bracket, as mentioned above. The early Broadmoors (and 707 and 717) fuel tank mount bracket did not have a metal barrier wall between the tank and the engine shroud. Thus, the tank can be modified by any good radiator shop (made a little more narrow and re-soldered). O r the mount can be modified to move the tank back a little bit in order to accommodate the slightly larger engine. The mounting bracket is a single piece and you should be able to find a replacement to put your tractor back to original when desired. I will look around to see if I have one for you!

Some 12 hp engines may have the same dimension, However, I picked up one that is substantially larger at the flywheel shroud, likely because of some synchro balance stuff (I am not an engine expert!.) I had to do a whole lot of changes to make that fit.


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