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Author Topic: Onan 6.5 points to electronic ignition conversion.  (Read 17609 times)
Barn Owl
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« on: October 02, 2008, 10:45:43 PM »

Overnight my ’79 Onan NH 6.5 started loosing power and seemed to be getting a sporadic spark and gradually is now getting a spark only once in a while. When I got the gen it had only 20 hrs on it and it now has 40. I have read that converting to electronic ignition makes a huge difference. I see that Onan makes a kit for $250 but I have read that some have used aftermarket kits from cars for ~$70. The car kit involves adding a magnet to the flywheel and therefore takes more time. I am leaning towards the car kit, but wanted to get as educated as possible before I decide what to do. Has anyone had any experience with this?

Thanks
« Last Edit: October 02, 2008, 10:48:09 PM by Barn Owl » Logged

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« Reply #1 on: October 02, 2008, 11:29:41 PM »

check with a company call PERTRONIX. they make conversions for a lot of motors. mostly for cars but the distributor doesnt know what it is in. they may make one that will fit your distributor and they are simple to install. I have used their stuff in several old cars and their stuff works great.
steve
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« Reply #2 on: October 03, 2008, 12:05:37 PM »

BO - check the cover on your points box - that model I believe had an Aluminum box/cover and were notorious for arcing to the cover - if you pull the cover you would be able to see it  - a piece of E tape at the right place would be enough insulation to remedy it - HTH
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TomC
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« Reply #3 on: October 03, 2008, 12:10:42 PM »

I had a 6.5 Onan with points that I converted to electronic.  The kit I used simply removed the points and put an electronic triggering switch in its' place.  Only one adjustment and then forget about it.  Best conversion made on the unit.  Now if it had electronic fuel injection to compensate for altitude, it would have been perfect.  I don't remember the cost of the conversion- $250.00 sounds high.  Good Luck, TomC
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« Reply #4 on: October 03, 2008, 05:45:55 PM »

I have the 6.5 gas and it is anemic.  I don't know if it was ever OK and I have owned it since 90 and it is a 73 model.  I seems to craw to starting speed after the "start" button is pushed.  Engaging any load seems to bring it to its knees before it pulls slowly back up to speed.  Always starts and runs....but?

From this board, I have been advised to inspect the intake valve for carbon buildup.  To do that I was going to jerk the gen out with a forklift.  I won't be able to position the fork for another couple weeks.

I did my points long ago and had good spark.  I figured the original system was adequate but now after breading this post I'm not sure.  Is the original ignition system repairable or should I just go for the electronic?  Lots of these systems just use the points as a signal for the Capacitive Discharge System.  That was a huge improvement in the day before magnetic pickup. Weak spark would answer a lot of questions for me.

Thanks,

John
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« Reply #5 on: October 03, 2008, 07:29:35 PM »

BO,

I had a '78 Model 7.5JB Onan that had points problems.

When I first got it it would run fine for 30 min and then shut down. After it cooled it would run another 30 min and shut down again. This became a pain! It was very slow to start also.

Short story, there was almost no point gap. I still don't understand how this thing ever ran? Once the points were properly gapped it ran fine if one could ignore the vibration and noise!!

Another weird thing about these things is that the points fired every other rev and both cyl fired at the same time. It was, in effect, a two cyl one cyl engine??

It was strong as an ox, twice as heavy as necessary and put out more heat than electric power. I gave it away and got a nice, lightweight, quiet Honda water cooled.
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« Reply #6 on: October 03, 2008, 09:11:39 PM »

http://www.shopatron.com/product/part_number=1123/591.0.26484.26485.0.0.0

If it a Delco distributor...you can change over to points less...still use the same old coil.

I have convert few single cylinder lawn tractor with pointless chips and never fail to spark every times. Love it...got tired from rope pulling few times with points version. Run smooth too!

Call them up if not sure if it will fit your 2 cylinder.

FWIW

Sojourn for Christ, Gerald
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« Reply #7 on: October 03, 2008, 09:27:11 PM »

Gus- I have a 6.0 DJB Diesel inline 2 cylinder that the pistons go the same direction, so with a 4 stroke, every revolution a cylinder fires-I think that's how your's worked too.
On the opposed 2 cylinder, couple of things.  I had one on my truck.  The first one lasted almost 12,000 hours without the heads ever being off.  What I did was when the gen was running, always turned on the block heater and pump so it had about a 1800 watt load at all times.  When it would start knocking and putting up a fuss, I'd get a good load on the gen, take off the air cleaner and spray carb cleaner into the engine while running-careful not to stall it.  Then when it was just about clear, spray a good load into it to stall it out and let it sit for 5 minutes, and restart.  Most carbon would be blasted out.  Onan makes a spray for decarboning-but it just about smells like carb cleaner.  Also, clean the spark plugs about once a month.  The carb should be adjusted when warm, and if adjusted properly, will take a load without dipping too much.  If it almost stalls out when a load is applied-it is running too lean.  Try unscrewing the carb screw at the bottom of the bowl about 1/8 turn.  Good Luck, TomC
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« Reply #8 on: October 04, 2008, 10:44:05 AM »

Barn Owl, converting that Onan will involve pulling it, removing all the shrouds on the front end and pulling the flywheel. The 'trigger' for the electronic sensor fits on the end of the crank behind the flywheel and the sensor bolts on two bosses on the timing cover. You will need a darned good grade of puller to get the flywheel off...they can be tough on an older unit.

The $250 price tag strikes me as high but a quick check with the local Cummins parts guy should firm that up for you.

The spray Tom was talking about is 4C (Carburetor and Combustion Chamber Cleaner) and is available from the Cummins or Onan guy. It really works! I've used it for years with excellent results. For a 6.5 use the whole can!

The JB gensets were not only hot and noisey the were hell on points and condensers. Thankfully there aren't too many of those old B@#$%^&s around anymore.

Good Luck with your project.

NCbob
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« Reply #9 on: October 04, 2008, 12:19:20 PM »

Here's the inside scope on Onan electronic ignitions from the Classic GMC Motorhome website

http://users.sfo.com/~eagle/generator.html#pentronic

Pentronix.
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.

TIMING
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.

Emery Stora

Pete RTS/Daytona
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« Reply #10 on: October 04, 2008, 04:25:24 PM »

  I just finish trying to do a repair on a MAGNA-ARC, (replacing the module with one spec for a small block GM), It work for 5 minutes & fail. So I got fed up & put the point system back on.  The MAGNA-ARC is no more available unless you find one sitting on a shelf. I call tech support at Pertronix, & got to talk to a tech who was very willing to help & was not shy on infos, but could not do any to send me a new unit.  I believe one with more patience & more of an achiever then me could do it easy..
   I still got all the comportments, some been modified a bit but are usable.
  So B.O. if you think you more of an achiever then me, just post a pict of the inside of your coach(so I can judge)LOL,LOL, send me your address, & I will send you my hardware.
             wrench
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« Reply #11 on: October 04, 2008, 07:39:36 PM »

Definitely nail down your current problem with the engine before considering the conversion. The old points system has always been a maintenance headache, but it's fairly simple and cheap maintenance. The engine should run well after if that's where your problem lies. The rest of the spark system isn't that complicated either....failing coil, failed insulation on the spark wires, and cracked/burned distributor cap/rotor are the other likely causes. Verify input voltage to the coil too.
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« Reply #12 on: October 05, 2008, 03:48:51 PM »

Distributor cap? 6.5 Onan's use a twin post coil that fires both spark plugs at the same time. Hmmm.
The longer I read this Board...the more I learn...and I was an Onan dealer for over 20 years.

I've changed quite a few Onan engines and generators over to the electronic system and found that..in the long run you're farther ahead to replace the points every couple of years and keep up on all phases of maintenance.

NCbob
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« Reply #13 on: October 05, 2008, 07:41:00 PM »

I bow to the experts on Onan specifics, so if you say there isn't one I'll believe you. But I've had plenty of experience with points ignition in automobiles. The basic nature of the gasoline spark system is pretty much the same no matter how big or small the engine is.
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« Reply #14 on: October 06, 2008, 12:28:23 AM »

NCBob,

Nice to hear that.  I would go to solid state in a heart beat...if need be. 

Two questions:

  Is it possible that my timing mark is not correct?  Can I compensate for that?

  My spark was not all that intense when I last looked.  How far should the spark jump at the spark plug end?

My poor power symptom would go with poor spark and/or retarded timing/ lean mix/loads of carbon around the intake valve.  Suggestions on the order I should follow to mverify?

Thanks much,

John
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« Reply #15 on: October 06, 2008, 05:46:43 AM »

JohnEd, on those rare days when I really felt like setting the timing on one of those rascals (most of the time they were in a hole where you couldn't see you hand in front of your face) they were mostly on the bench. In order to see the timing marks there was a lot of tin to remove. Generally speaking if you make sure the point plunger is DOWN and install and set the points (.018) and button it up. I rarely saw timing as a problem on these small engines.

If you can find one of the old vibrating reed freq. meters you can set the speed by simply resting the meter somewhere on the genest. It will sense the vibrations and give you an accurate 61 Hz to set the speed.

Best of luck,

NCbob
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« Reply #16 on: October 06, 2008, 04:03:16 PM »

If you can find one of the old vibrating reed freq. meters you can set the speed by simply resting the meter somewhere on the genest. It will sense the vibrations and give you an accurate 61 Hz to set the speed.

Best of luck,

NCbob

Or plug in a 110 v ac dial clock or analog into generator that side by side to your cell phone’s seconds or better yet another analog clock plug into land line power source. If generator is running too fast…it will cause the “generator clock” to run faster than land line power clock and will result a higher voltage.
Adjust your generator engine governor to slower or faster RPM until both analog clocks second hand is running the same speed or time matches. You should be in the 120 volt range after the adjustment.
All ac analog clock speed is depending by the cycle per second. Which is USA standard of 60 cycle.

Sojourn for Christ, Gerald
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« Reply #17 on: October 07, 2008, 08:13:46 AM »

That's one of the nice things about my Trace inverter-it has a hertz readout to make generator speed adjustment a snap.  Good Luck, TomC
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« Reply #18 on: October 07, 2008, 07:00:05 PM »

TomC,

The reason I figured this thing couldn't fire the two cyl separately is that it had only one lobe on the cam so the points opened at the same place ever time.

It may be that one spark plug fired during an exhaust stroke and the other during compression, I was never really interested enough to check out piston position.

My guess is that your JBD also has the pistons moving together if my guess is correct about the gas setup.

A four stroke fires every other revolution, only a two stroke fires every revolution. Two strokes, one down, one up = one revolution.


NCBob,

I wondered about that distributor part, I couldn't remember any dist on mine?
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« Reply #19 on: October 07, 2008, 07:13:48 PM »

If it does fire both cylinders at the same time it is called a wasted spark ignition. we used that on some of our race motors. seems odd but works fine.
steve
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Barn Owl
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« Reply #20 on: October 07, 2008, 10:25:18 PM »

I just got back from my last campout for the year and I am now soaking all of this in. Keep posting if you can.

Thanks
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Have fun, be great, that way you have Great Fun!
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