Old Briggs mag ignition

[OldYellr]

A couple of years ago I bought an old John Deere Model 68 riding mower. It has a Briggs 8-11 hp engine. It started and ran fine since I had it, but recently it began stalling and became hard to start, finally not starting at all. It looked like I was getting an intemittent, weak spark, then none at all. When I took the ignition apart I found it was not like what's shown in the parts book, because it was missing the breaker points and condenser (no cam plunger in the casting) and the primary of the coil (armature) was connected to the kill circuit. Basically, it's the same as a standard system without the internals. I'm thinking the engine is a lot older that the original was. I tried another coil I had kicking around from a similar engine, but still didn't get a spark, so I'm thinking this coil has to be different, although it looks the same. Any idea what I've got, how to test it and how to make it work?

[Mike S]

It sound like you have electronic ignition. Look on the shroud for a CODE number. The first two numbers are the year. Briggs went to electronic in 1981.

[Andrew Mackey]

B&S Magnetron Coils were also retrofitted to engines with excessive bearing wear as well. The Magnetron coil uses the magnets to trip the timing, eliminating erratic point timing due to worn bearings. You could keep an engine running, until the flywheel knocked the coil off its mount! The only draw back to magnetron - It needs a minimum of 700 RPM to trip reliably. A lot of older people cannot pull the engine over that fast. This forces most elderly to buy a mower or snow blower with electric start (another $125 please!).
Andrew