12 Volt Ignition Conversion

[John_RI]

Sounds great Rob! Seems like a nice improvement. Simple and I really like the "no disassembly of the engine" (or tractor) aspect of it. I just got a sim 725 with an 8 hp briggs and have yet to get a spark. I might give it a try. Thanks again, John(ri)

[richp]

What a great idea.....For the high voltage wire from the 12 volt coil to the spark plug i am thinking of using a old auto spark plug wire...cutting the end that normaly goes to the distributer cap and putting a "stake on" connector to allow for securing to coil and the other end will have the original spark plug connector on it....what do you think? Thanks,Joe

[Kent]

Since Kent has updated my "Work In Progress" narrative in the gallery I have received numerous inquiries with reference to the details of converting the magneto coil ignition to a 12V coil ignition. The advantages of switching over to a 12V coil is that it's simple, no disassembly of the engine or machine is required, you obtain a constant hot spark regardless of engine speed, you don't have to worry about the magneto coil going bad and having to tear down the engine, and the required parts are inexpensive and available at a local auto parts store. The constant hot spark regardless of engine speed makes for excellent cold starts and it's impressive how low an idle speed can be achieved. Since these tractors already have a 12 Volt battery it makes this a simple, inexpensive conversion. In the gallery it says that the parts cost $4. This was a typo, $40. is more like it. Required Parts: 1. Automotive Type Coil, 12Volt, W/Internal Resistor. I used a KEM model U12K. I also used the strap type bracket made by KEM. 2. Condenser. A 12V condenser to go with the new coil. 3. High Tension Lead. A solid wire high tension lead. This could be made with a kit or a local equipment shop should have a spool of wire and an assortment of ends. 4. The OEM Points. 5. Toggle Switch, Single Throw. I chose to mount the coil horizontally on the firewall in front of the gas tank. Leave enough room at the top of the coil so that the new high tension lead will not be pressed against the side of the voltage regulator. The original magneto coil can be left in and it's high tension lead (plug wire) can be thoroughly taped with electrical tape. I tucked the wire down & in so its out of the way. I don't recommend tucking it under the gas tank, unless of course you're into building bombs. Be sure to disconnect the neg terminal of the battery. From the pos. term. on the battery or from the proper term. of the voltage regulator run a wire to the toggle switch. From the other switch lead, run a wire to the plus side of the coil. You now have switchable 12 Volts to the coil. This is used to cut off the ignition and kill the engine. From the neg. side of the coil run a wire to the points. I mounted the condenser at one of the screws at the valve inspection cover. This grounds the body of the condenser and allows for running the condenser wire straight down to the points. Be sure the connection of these wires to the points is isolated from the engine block. Clean the points and set the gap to 0.020 I re-installed the points cover with the notch side up. I widened the notch so that the condenser wire and the wire from the neg. side of the coil would fit. I cut a small rubber grommet in half and placed it in the notch to protect the wires from rubbing through and grounding out. A small blob of silicone will work just as well and will keep the points dry. Connect the high tension lead from the coil to the sparkplug. Re-connect the battery. Done. Any questions, post a reply or send an e-mail. To some, this may seem elementary but I tried to be overly descriptive for those less familiar. My B210 is in the Gallery and is titled "Work In Progress." There is a photo of the engine compartment included there.