Upside Down Briggs

cashman

Well-Known Member
Joined
May 23, 2013
Threads
9
Messages
283
Anyone have a mower with one of these on it? It's called an upside down because the starter, coil and flywheel are mounted under the engine. The blade mounted directly to the flywheel.





They didn't build these long. I think the idea was to simplify tune ups and with out the blower housing was cheaper to build. The only ones I ever saw were on Penncrest mowers sold by J.C. Penney.
 

manioso

Forum Newbie
Joined
Sep 12, 2013
Threads
0
Messages
1
This engine was a Briggs Sonoduct, first built in 1960. Contrary to original poster, design was meant to lower center of gravity, not necessarily to improve serviceability. In fact engine was more difficult to service ignition, as engine would have to be removed from mower for any points, condenser, or coil service.

Would have been a better design 20 years later with electronic (Magnetron) ignition. In fact, descendants of this design are the "half crank" 2 stroke engines commonly seen on low price weedeaters, blowers, etc.
 

reynoldston

Lawn Pro
Joined
May 23, 2011
Threads
92
Messages
5,705
I have seen a lot of different engines designs more so on the much earlier engines. For some reason they always seem to go back to the standard designs. They are always improving on them all the time. The newer engines all seem to have more HP and better fuel use. Yes they do have design flaws now and then but they do correct them.
 

EngineMan

Lawn Addict
Joined
Jun 12, 2012
Threads
9
Messages
2,275
Could you post up the engine number, would like to look into this one...!
 

cashman

Well-Known Member
Joined
May 23, 2013
Threads
9
Messages
283
Here tis. 1st. set of numbers. 80802, 2nd. set of numbers, 947025, 3rd set of numbers, X12310, cancel 1st. numeral in last. Think maybe 9?
 

EngineMan

Lawn Addict
Joined
Jun 12, 2012
Threads
9
Messages
2,275
This engine was a Briggs Sonoduct, first built in 1960. Contrary to original poster, design was meant to lower center of gravity, not necessarily to improve serviceability. In fact engine was more difficult to service ignition, as engine would have to be removed from mower for any points, condenser, or coil service.

Would have been a better design 20 years later with electronic (Magnetron) ignition. In fact, descendants of this design are the "half crank" 2 stroke engines commonly seen on low price weedeaters, blowers, etc.

The points and condenser are at the top, only the coil is at the bottom.

https://www.dropbox.com/s/hrx2hc9dgbjpcar/80600-ms4030-0192.pdf
 
Top