I went to a garage sale and saw this engine sitting there with a $25 "as-is" price tag on it. Hmm, I can't pass that up now can I. So home it came. The guy selling it said he had the piece of equipment it came out of, an AgriCat mini dozer (the Briggs being replaced with a modern engine). He said this Briggs probably still ran Uh-huh, sure. At least the crankshaft turned over and the engine had compression. What I don't understand is why he would sell the original engine out of a 1950 AgriCat. I'm not complaining by any means, it just doesn't make sense to me.
This engine is cast iron, so it is heavy and was built for rough service. When I got it home, I pulled the spark plug and found it had spark, so I did just put gas in it and tried to start it, after checking the oil level. A funny thing happened. After several pulls of the starter cord, it popped off but then the crankshaft went backwards. It bounced off compression in reverse, then rotated forward and fired backwards again. It did this for six or eight non-revolutions before it stopped. I'm guessing the timing is way advanced, and that's probably why the engine was pulled off the AgriCat. I tried to start it again and I was successful, although it seemed to run a little odd, so I shut it down.
The next step was to check the timing. The shroud came off, then the flywheel. It's strange that the flywheel isn't keyed to the crankshaft like a normal small engine. That's because the magnet for the magneto is mounted directly to the crankshaft behind the flywheel. Normally the magnets are integral to the flywheel, in which case the flywheel would need to be keyed to the crankshaft.
I used a makeshift puller to get the flywheel off. After the bolts were tight, I used a six pound sledge hammer and the flywheel popped loose after a couple whacks on the steel plate.
In the photo below, you can see the magnet assembly. It's the round silver disc that is attached to the flywheel. The rust-colored thing with the coil is the magneto.
I wire-brushed the parts and found timing marks on the magnet and magneto.
There's an arrow on the magneto body and three numbers and dashes cast into the magnet case. The numbers are 23, 9, and 14, which I'm guessing are the timing marks for those model engines. Going with that notion in mind, I set about finding the exact place in crankshaft rotation that the points just open, then adjusted the magneto arrow to the "23" mark (the model of this engine). Incidentally, the timing was originally about at the "14" mark, so quite a bit advanced from where it should be. The thing I don't quite understand is that the actual points are in a separate external can on the side of the engine, so moving the magneto doesn't really change the points timing. I'm still trying to wrap my head around that one.
This next photo shows how I used a multi-meter to find when the points open. I first had to disconnect the magneto wire that was connected to the points, then connected the multi-meter to the points and found when continuity through the points was broken.
Once the engine was all back together, it started up on the third pull. It runs amazingly well. Now I just need to find an AgriCat to put it in. The previous owner did show me his machine when I bought the engine but recently when driving past his house, I didn't see it in his yard. He did say he had someone interested in it so maybe he sold it. He said it was probably worth $2,500. Wow. On second thought, I don't think I'll be getting one anytime soon. The new owner would probably like to get this engine back....
This next photo is of an AgriCat that I grabbed off the net. The site said it was a 1949, and that engine looks strikingly similar to mine. Hope they don't mind me posting the photo. Notice the two steering levers next to the gas tank. My tank is bashed in a bit, and now I know what caused the damage.
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