My Mower with the Slant Fin Briggs 'FI' Engine


| May/June 1997



The mower shows the open gears

This view of the mower shows the open gears that drive the blade.

7574 S. 74 Street Franklin, Wisconsin 53132

When I first saw the photo of the old lawn mower, with a slant fin Briggs 'FI' engine to power it, I knew that I wanted it. It would increase my power mower collection to 70, but how could I pass it up? The serial number on the engine dated it to 1927. There was no manufacturer's name on the mower, but it looked complete. The first problem to overcome, however, was the fact that the mower was in northeast Pennsylvania and I am in Wisconsin and this was January. I paid for the mower and in June our family was going to the Coolspring, Pennsylvania Show anyway, so a trip across the state of Pennsylvania was in the plans to retrieve the mower. It is a six hour drive from Coolspring to Stroudsburg, but I thrilled my wife with stops along the way, to look at other engines. The poor mower was mostly rusty, but at least it was complete. I removed the handle and gas tank and loaded it into our already full Taurus wagon for the trip back to Wisconsin.

When I had the mower home, I photographed the mower from every angle possible. This was a lifesaver later on. I highly recommend taking many photographs of a project before and during disassembly. They are great to refer to later. You never know when you will be looking at one of the photos with a magnifying glass to find out about one detail (was the bolt head or nut on the outside?). Also, I made sketches of the mechanical linkages and dimensions where the different parts were placed on the shafts.

Upon disassembly, I found that the sheet metal deck was beyond repair. Also, several generations of mice had taken up residence in the sheet metal drive roller and their urine rusted through the sheet metal. One cast iron clutch dog was broken and the loose parts missing. One gear and axle in the main gear case was worn horribly in the axle hole from lack of lubrication. When designed, it was a cast iron gear running on a steel shaft with absolutely no way to get oil to the axle. One brass chain sprocket was worn beyond future use. Stupid me broke the magneto plate on the Briggs FI engine while disassembling it. These things could all be overcome.

I hired a local sheet metal contractor to bend me a new deck and roll the sheet metal for the roller and braze them to the cast iron ends. Since I do foundry work as another hobby, I used the good clutch dog as a pattern and cast up two (one extra) cast iron replicas. I machined one, so that I now had a pair. I bought a new gear and machined it for an 'Oilite' oil impregnated bronze bushing and machined a new axle. I had to create a replacement brass sprocket by machining one from brass plate. I also learned that in 1929, woodruff keys were made in different sizes than they are now. You would not believe the number of people who think I am crazy, restoring old iron!

I always look at ads and various papers at the shows, looking for old lawn mower literature, I found a 1929 ad for my mower! It was a Cooper, made in Marshalltown, Iowa. I know that they made mowers into the '60s and built a mower called the 'Cooper Klipper.' Somehow I found out that Cooper is still in business, although not building mowers anymore. I contacted them and was referred to a retired Mr. Cooper. From him I was able to learn a little about my mower.