Here's the inside scope on Onan electronic ignitions from the Classic GMC Motorhome websitehttp://users.sfo.com/~eagle/generator.html#pentronic
I got the directions on how to do it from Ken Henderson's and Lawrence Gaskins' previous postings here.
The postings are long so please go back and look at the following:
1. Ken Burton - Onan Ignition Timing - posted on 8-28-03 at 4:48
2. Here is Ken Henderson's posting to the GMCphoto site: http://www.gmcmhphotos.com/photos/showgallery.php?cat=3608
3. Here is Lawrence's write up with pictures: http://www.picturetrail.com/gallery/view?p=999&gid=1344546&uid=649762
I followed Ken's example except I mounted the pickup further clockwise around the flywheel and added an extra ground wire. I also set my timing at
25 degrees BTDC. If you read my posting you will see why I chose that setting. If you do not like my reasoning then use whatever is marked on the
flywheel. ken Burton
Onan Electronic Ignition by Chuck Aulgur
Before you start this project, be sure to read the article above to determine if you need a new baseplate for your Onan. The early models need this extra part. I feel the Onan should be running before your start this project. Also set the timing as talked about below, so that after you install the electronic igniton, you will know the Onan worked at this timing before. gene
Onan Electronic Ignition by Emery Stora
photos by Mr.C
The Onan electronic ignition system can be made to fit all Onan twin-cylinder engines and generator sets built since 1973 with top adjust points. This includes all (Model NH) Onan generators installed on GMCs. It is called Magna Arc, part number 160-1376. I believe this is the only one they have called Magna Arc. It contains an ignition module, cover and cover clip, base plate and gasket. It sells for approximately $120 .
This new unit will not fit as is comes out of the package. The main problem with the new unit is there is insufficient room to make adjustments to the adjusting screw, so you can cut off both right angle sheet metal bends that hold the adjusting screw and discard the adjusting screw, spring and washers. It is very easy to do this with one cut.
Hold the unit with the black block toward you and the adjusting screw to your right. Loosen the adjustment hold down screw and move the two metal bracket pieces so that they are lined up even on the left side. This will give you enough adjustment slot to time the engine.
Remove the adjusting screw, spring and washers and make a cut with a hacksaw on the right side just even with the outside of the hold down washer. Throw away the two small pieces you cut off. File the cut edges smooth.
Then remove the points and condenser from the old base plate and remount the new parts to the old base plate, using the new base gasket. The new components will screw down under the two screws used to hold the base plate. You will need to file a few thousands off the inboard side of the threaded post protruding up from the base plate to provide clearance to mount the assembly. If you do not do this, the push rod pin will jam in the bracket and not go up and down.
Then time the engine using a timing light per the instruction sheet. Disregard a lot of the timing instructions that come with the new kit. They talk about marking the shaft and even removing the cover. You don't have to do that with our Onans.
We have a small hole, about 1/2" in dia. on the top inside of the fan housing for timing marks. Start the engine by holding the two parts of the assembly roughly even and moving them slightly to get the engine running smoothly. If the engine will not start, make sure the white magnet bar is moving back and forth when you are cranking the engine. The push rod might be jammed as described above.
Point your timing light at the hole and there will be a single timing mark. Your timing light can hook up to either of the plugs. Both fire at the same time. Move the bracket by finger adjustment until the timing mark lines up in the hole. Then tighten the locknut on the adjusting back plate when the timing is correct.
The new cover has a grommet that fits over the wires. If you drill a hole in the new cover in the same location as the old cover screw hole on the top it will fit and you can discard the new cover clip.
There are two wires coming out of the module. The red one goes on the hot (+) lead to the coil (the back one on mine). The black lead goes to the ground (-) side of the coil. The old points had a push on connector. The new black lead has a ring connector so it will be necessary to get a nut that fits the threaded terminal. The Onan is much easier to start and performs exceptionally well.