Final Steps of Restoring ‘TheTwin’ Jacobsen Engine

Reassembly begins with a challenging rebuild phase and finishes with the magneto, fuel system and starter-part 3 of 3.

| October/November 2020

twin-engine 

The magneto mount was a disaster from the beginning. The mag was not straight on its mount, and the mount itself was off center from the crank on its mounting board. The board was split in two, and its mounting lag bolts were only into the sides of the cart rails by about 1/2 an inch.

Repairing the Magneto

The WICO X magneto was bolted to a cast-iron mount plate that had a section at a right angle to the base. This angled section has a hole in it that acts as a cage for the Lovejoy connection between the mag and engine. The magneto also has an impulse coupler that retards the spark for ease of starting. It is set at top dead center compression for initial timing and advances automatically once the engine gains speed. The cast-iron mount block was slightly bent where the magneto bolted up, making it tilt about 15 degrees from parallel to the engine crankshaft.

As I mentioned before, the wooden base the mag mount was bolted to was intact, but the piece of wood the base was mounted to was broken in half. The lag bolts that mounted the entire assembly had ripped out of the rails of the cart. These bolts were way too short for the job. A run to the hardware store produced the needed piece of wood and longer carriage bolts to mount it to the frame rails, and then the fun began.



Piled-on-solder
Piled-on solder cover the ends of cast-iron brackets.

I took the assembly apart and decided to test the mag for spark. It was dead. Absolutely nothing from either spark plug wire. I thought that, since the mag was not grounded to the engine, perhaps the coil was bad, but I decided to have a look inside the cover to see what I could see. The four screws came out of the cover easily, and when I turned the mag over, I saw the problem. The points were not opening. I loosened the points’ mount screws and set the points’ running block on the high spot on the cam lobe, and set them at about .018 inch by eye. I tightened the screws.



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