As reported June 20, 2022, the Bosch DU-4 Dual Magneto was working on the bench.  The next day I started to make the modification of the dash board to accommodate the somewhat smaller diameter of the Bosch switch & coil vs. the larger diameter Briggs switch & coil. I got it all wired in and timed by June 29, 2022.

My custom turned collar and plywood back plate for the Bosch switch and coil.

Bosch switch & coil installed. The Briggs switch & coil & mag soon to be removed.

After completing the change over to the Bosch setup, we tried a start. It was miraculous. I primed the engine by pulling the choke wire, cranking the engine 4 or 5 quarter turns, switched the switch to battery and pushed the shower of sparks button.  Pop pop pop vroom!  She started right up!  Hooray! Problems solved. Then I turned the switch to the Mag. setting and there was a slight change in the RPMs, but otherwise it was idling just fine. Eureka!

Janet & I took several short trips around the neighborhood to confirm that the car was running on both BAT. and MAG.  It was.  There was some stumbling when accelerating but this was probably an ongoing carburetor issue. NOT an ignition issue. We were happy and my Dad, sister Susan and her husband Dan were due for a visit in early July. We would have a lovely drive in our all but completed car………….

Ahem…….. not so fast buddy.

First it flung the cover for the interrupter (points) off into the street. Which didn’t cause it to immediately stop because the piece is only needed to short out the magneto circuit when you want the car to stop.  We didn’t see it leave the car, but it couldn’t have been too far because our drive had been short. What is amazing is that we didn’t discover that it was gone until 2 days later. We drove along our route from 2 days before at about 2 miles per hour with our doors open looking at the street. Janet spotted it on the curb where some thoughtful neighbor placed it.

Interrupter cover for Bosch DU-4 Dual magneto. Found by Janet on the curb North-east corner of Hillside and Sunnyhill.

The cover went back on the magneto and we got another couple of rides out of the car over the next few days. The last time we took it out before my Dad & sister arrived the engine got fairly warm. The Motometer on the radiator indicated HOT, and the overflow pipe was spewing steam.  We had gone on a “long” ride — about 5 to 7 miles. The engine was stumbling when it limped back into the garage. Not a good sign.

For context, you must remember that this magneto (the “new” Bosch) is over 100 years old.  It had been sitting unused for probably 80 years. That insulating resin in the coils and windings hasn’t been in a  hot engine compartment for a long long time.  It could melt and fail at any time.  And it did.

When my Dad, sister and hubby Dan arrived all ready for a ride in the newly completed Michigan – it refused to start. Not a cough or sputter. The “new” magneto was dead. We took pictures anyway  – even if we had to roll the car out and then back into the garage.

July 10, 2022 L to R: Dan Kehler, Janet, Susan Kehler, Vince Correll, Craig. All disappointed because the magneto failed.  But the 48 star flags look nice on the radiator. They are 1912 appropriate – both Arizona and New Mexico joined the Union in 1912.

So……. we need to send the magneto off for repairs. Our Horseless Carriage consultants recommended Bob Smith, the MagnetoDoc of Gardenerville NV. On July 11, 2022,  I called Bob, and let him know a heavy package was on its way to his place. Then I crossed my fingers. Would this be a long term solution?  Only time will tell.

Two days later, Bob confirmed by phone that our troublesome mag had arrived. He noted that someone had reversed the base and had probably had it opened up during its prior life. I just wanted reliable — “Bob please proceed to fix what looks iffy or typically fails.”

I got our mag back from Bob on August 20, 2022.  Would it work?

Freshly refurbished Bosch DU-4 Dual Model 5, magneto. This thing should work.

On August 23, 2022, I gleefully installed the mag and set to timing the car.  It wouldn’t start.  I retimed the car setting the fly wheel to #1 & 4 to TDC and watching the battery interrupter points just barely start to open as the fly wheel hit TDC — just as I had before.  It wouldn’t start, just a single pop and maybe a backfire. I timed it again. One pop. I checked the battery.  I timed it again to the magneto points. (This car has points for battery start and points for running on magneto– hence the word “DUAL” in the description. And they are a couple of degrees different.)  No change – one pop and maybe a backfire when cranked. I let the car sit for a day or two. When things get frustrating, parts sometimes get broken.  I called Bob and asked for advice. He said check the wiring.

I pulled the entire thing out of the car and put it on my bench testing rig. It all worked as it should. Nice strong sparks on BAT. Nice strong spark on MAG. Nice shower of sparks on single plug when set to BAT and shower of sparks button pushed (also called trembler button).  Everything works.  Hmmmm. What’s wrong with my install?

Bench testing the Bosch DU-4 Dual Model 5 magneto. Everything worked as it was supposed to work.

Since the entire wiring harness was out of the car, I decided to upgrade the stranded ground (positive from battery) wires to a large terminal lug end that would fit the 3/8″ mounting bolts for the magneto bracket. Otherwise, I changed nothing.  I reinstalled the magneto, timed it to the magneto points (not the battery points) and attempted a start.

Pop pop vroom. We have ignition. Yea. Finally. Jeez what a hassle.

I reported my success to Bob Smith who was pleased to hear that our Michigan was alive. That was on August 28, 2022.  It is time to go test the car some more and see what else will unscrew itself or fall off.