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| Pertronix install on Onan mysteries [message #278782] |
Sun, 31 May 2015 12:53  |
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RF_Burns
Messages: 2277
Registered: June 2008
Location: S. Ontario, Canada
Karma: 3
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Senior Member |
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Ok, first off, Murphy's law follows me everywhere so no doubt most others have not have this problem.
First, even before the epoxy had even cured, I discovered that I installed the magnet with the wrong side towards the Pertronix sensor. Then, since the markings were gone from the magnet, I did it again! Then I got smart, I used a compass to find the South Pole of the magnet. I got the space gap set to 0.025" but it would not start, just the odd firing (this could be when I let off the Start button and the coil collapsed causing a spark at any point in the cycle).
So I disconnected the Pertronix and reconnected the points and it starts right up, so not a fuel issue.
Just to see what is happening, I connected a 12V LED string in place of the coil on the Pertronix. Slowly turning the flywheel with the magnet under the sensor, the LEDs would go off (Coil field would collapse and spark occur) but the OFF time was very short, like 1/2 the top width of the ring gear tooth. Doing some calculating, the OFF time to the coil is less than 1 degree, meaning at 1800rpm, the time for the coil to collapse is about 0.1ms. I believe that's hardly long enough...?
So I removed the Pertronix module and move it over the magnet across different areas of the sensor. Turns out on mine, centering the magnet's pass directly under the yellow dot (where I carefully installed it to be) is about the least sensitive spot. If I move it to pass under the edge opposite from its mounting point, I'll be able to extend the off time to about 1/4" across the Pertronix's face. Ok, I'll try that but I need to wait till tomorrow to try again as the epoxy needs to cure again!
So, that 1/4" of travel across the face = ~2.3degrees of rotation and will last 0.2ms. I still think that is too short for the coil field to collapse.
Another concern I have is the coil duty cycle. On the old points system, the points are open until a few degrees before spark is desired, then they close and the field builds up in the coil. The points then open, the coil field collapses and spark occurs igniting the cylinder mixture. The points then stay open until just before the next firing and repeats.
My observation of the Pertronix is coil current is supplied the entire time until the magnet crosses the face of the Pertronix sensor. In my case 360-2.3 = 357.7 degrees of rotation or 99.4% of the time. In the case of my coil, that's about 45watts of power.
In a normal Pertronix installation there are 4-8 magnets on a disk that is a couple inches in diameter, running at 1/2 engine speed meaning each of the many magnets are moving much more slowly across the Pertronix sensor. To match the points system, we would actually need to run a strip magnet around the circumference of the flywheel. Or invert the output and use a magnet a couple inches long.
Has anyone noticed failures of the Onan coils after the Pertronix installation?
What is the ideal OFF time for a coil to collapse and fully fire a spark plug?
I know I reading too much into this.
thanks guys.. and thanks to Gary Bovee for his excellent kit and his help.
Bruce Hislop
ON Canada
77PB, 455 Dick P. rebuilt, DynamicEFI EBL EFI & ESC.
1 ton front end
http://www.gmcmhphotos.com/photos/showphoto.php?photo=29001
My Staff says I never listen to them, or something like that
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| Re: [GMCnet] Pertronix install on Onan mysteries [message #278786 is a reply to message #278782] |
Sun, 31 May 2015 14:00  |
gcbgold
Messages: 60
Registered: August 2012
Karma: -1
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Member |
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Bruce,
I agree with you that the yellow dot painted on the bottom side of the
module at the factory is not alway accurate. I test every module to be sure
it is working and also paint a white strip on the front side of the module
so the installer will know where to line up the magnet so it passes
correctly under the module for best performance.
In the 7 years I have been reading posts here I am unaware of ever reading
about a coil failure from anyone using a pertronix electronic ignition. I
have run mine for a couple hundred hours problem free.
I have had NO complaints from anyone since I started selling the Electronic
Ignition Kits 16 months ago because of a coil failure.
Basically the only complaints I have ever had were from folks trying to
install my Kits who did not follow the instructions. This is getting off
topic, but please read and follow the instructions. The Kits work great.
(Smile)
Gary Bovee
Red Bluff, CA
1978 Royale
On Sunday, May 31, 2015, Bruce Hislop wrote:
> Ok, first off, Murphy's law follows me everywhere so no doubt most others
> have not have this problem.
>
> First, even before the epoxy had even cured, I discovered that I
> installed the magnet with the wrong side towards the Pertronix sensor.
> Then, since
> the markings were gone from the magnet, I did it again! Then I got smart,
> I used a compass to find the South Pole of the magnet. I got the space gap
> set to 0.025" but it would not start, just the odd firing (this could be
> when I let off the Start button and the coil collapsed causing a spark at
> any
> point in the cycle).
>
> So I disconnected the Pertronix and reconnected the points and it starts
> right up, so not a fuel issue.
>
> Just to see what is happening, I connected a 12V LED string in place of
> the coil on the Pertronix. Slowly turning the flywheel with the magnet
> under
> the sensor, the LEDs would go off (Coil field would collapse and spark
> occur) but the OFF time was very short, like 1/2 the top width of the ring
> gear
> tooth. Doing some calculating, the OFF time to the coil is less than 1
> degree, meaning at 1800rpm, the time for the coil to collapse is about
> 0.1ms.
> I believe that's hardly long enough...?
>
> So I removed the Pertronix module and move it over the magnet across
> different areas of the sensor. Turns out on mine, centering the magnet's
> pass
> directly under the yellow dot (where I carefully installed it to be) is
> about the least sensitive spot. If I move it to pass under the edge opposite
> from its mounting point, I'll be able to extend the off time to about 1/4"
> across the Pertronix's face. Ok, I'll try that but I need to wait till
> tomorrow to try again as the epoxy needs to cure again!
>
> So, that 1/4" of travel across the face = ~2.3degrees of rotation and will
> last 0.2ms. I still think that is too short for the coil field to
> collapse.
>
> Another concern I have is the coil duty cycle. On the old points system,
> the points are open until a few degrees before spark is desired, then they
> close and the field builds up in the coil. The points then open, the coil
> field collapses and spark occurs igniting the cylinder mixture. The points
> then stay open until just before the next firing and repeats.
>
> My observation of the Pertronix is coil current is supplied the entire
> time until the magnet crosses the face of the Pertronix sensor. In my case
> 360-2.3 = 357.7 degrees of rotation or 99.4% of the time. In the case of
> my coil, that's about 45watts of power.
>
> In a normal Pertronix installation there are 4-8 magnets on a disk that is
> a couple inches in diameter, running at 1/2 engine speed meaning each of
> the many magnets are moving much more slowly across the Pertronix sensor.
> To match the points system, we would actually need to run a strip magnet
> around the circumference of the flywheel. Or invert the output and use a
> magnet a couple inches long.
>
> Has anyone noticed failures of the Onan coils after the Pertronix
> installation?
>
> What is the ideal OFF time for a coil to collapse and fully fire a spark
> plug?
>
> I know I reading too much into this.
>
> thanks guys.. and thanks to Gary Bovee for his excellent kit and his help.
>
> --
> Bruce Hislop
> ON Canada
> 77PB, 455 Dick P. rebuilt, DynamicEFI EBL EFI & ESC.
> Hubler 1 ton front end
> http://www.gmcmhphotos.com/photos/showphoto.php?photo=29001
> My Staff says I never listen to them, or something like that
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:
> http://temp.gmcnet.org/cgi-bin/mailman/listinfo/gmclist
>
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| Re: [GMCnet] Pertronix install on Onan mysteries [message #278800 is a reply to message #278786] |
Sun, 31 May 2015 17:57 |
Ken Henderson
Messages: 8726
Registered: March 2004
Location: Americus, GA
Karma: 9
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Senior Member |
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Bruce,
I think you're over-thinking the dwell situation. As you probably know, I
was probably the second or third one to follow Lawrence Gaskins' lead with
the Pertronix. Later, I considered doing what Gary's now doing, and
consulted with Pertronix to find the best module to use (they suggested VW,
which was NOT better than the one Gary's using). Their engineer express
some concern about the dwell time, just as you have. Like Gary, I've never
heard of a coil failure attributable to the Pertronix.
RTFI! :-)
Ken H.
On Sun, May 31, 2015 at 3:00 PM, Gary Bovee wrote:
> Bruce,
>
> I agree with you that the yellow dot painted on the bottom side of the
> module at the factory is not alway accurate. I test every module to be sure
> it is working and also paint a white strip on the front side of the module
> so the installer will know where to line up the magnet so it passes
> correctly under the module for best performance.
>
> In the 7 years I have been reading posts here I am unaware of ever reading
> about a coil failure from anyone using a pertronix electronic ignition. I
> have run mine for a couple hundred hours problem free.
>
> I have had NO complaints from anyone since I started selling the Electronic
> Ignition Kits 16 months ago because of a coil failure.
>
> Basically the only complaints I have ever had were from folks trying to
> install my Kits who did not follow the instructions. This is getting off
> topic, but please read and follow the instructions. The Kits work great.
> (Smile)
>
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Ken Henderson
Americus, GA
www.gmcwipersetc.com
Large Wiring Diagrams
76 X-Birchaven
76 X-Palm Beach
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| Re: [GMCnet] Pertronix install on Onan mysteries [message #278861 is a reply to message #278800] |
Mon, 01 June 2015 19:45 |
GMC.LES
Messages: 505
Registered: April 2014
Karma: -2
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Senior Member |
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You shouldn't trouble yourself too much about the dwell angle. In the original application, the 8 magnet pertronix unit fires an ignition coil 8 times per distributor revolution. That is 4 times per crank revolution. Do the math. Our Olds V8 spinning at 3000 rpm triggers it's coil 12,000 times per minute. An Onan running at 1800 rpm triggers it's coil only 1800 times per minute.
Les Burt
Montreal
'75 Eleganza 26'
The EWIP (Eternal Work In Progress)
> On May 31, 2015, at 6:57 PM, Ken Henderson wrote:
>
> Bruce,
>
> I think you're over-thinking the dwell situation. As you probably know, I
> was probably the second or third one to follow Lawrence Gaskins' lead with
> the Pertronix. Later, I considered doing what Gary's now doing, and
> consulted with Pertronix to find the best module to use (they suggested VW,
> which was NOT better than the one Gary's using). Their engineer express
> some concern about the dwell time, just as you have. Like Gary, I've never
> heard of a coil failure attributable to the Pertronix.
>
> RTFI! :-)
>
> Ken H.
>
>
>> On Sun, May 31, 2015 at 3:00 PM, Gary Bovee wrote:
>>
>> Bruce,
>>
>> I agree with you that the yellow dot painted on the bottom side of the
>> module at the factory is not alway accurate. I test every module to be sure
>> it is working and also paint a white strip on the front side of the module
>> so the installer will know where to line up the magnet so it passes
>> correctly under the module for best performance.
>>
>> In the 7 years I have been reading posts here I am unaware of ever reading
>> about a coil failure from anyone using a pertronix electronic ignition. I
>> have run mine for a couple hundred hours problem free.
>>
>> I have had NO complaints from anyone since I started selling the Electronic
>> Ignition Kits 16 months ago because of a coil failure.
>>
>> Basically the only complaints I have ever had were from folks trying to
>> install my Kits who did not follow the instructions. This is getting off
>> topic, but please read and follow the instructions. The Kits work great.
>> (Smile)
>>
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:
> http://temp.gmcnet.org/cgi-bin/mailman/listinfo/gmclist
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| Re: Pertronix install on Onan mysteries [message #278876 is a reply to message #278782] |
Mon, 01 June 2015 21:46 |
JohnL455
Messages: 4447
Registered: October 2006
Location: Woodstock, IL
Karma: 12
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Senior Member |
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Most electronic switching systems limit current at low RPM as the dwell time is so long, saturated is saturated. Question is, is 1800 considered low RPM and is limiting in effect. I have only instslled one Pertronics in a 69 GS400 and couldn't get a good answer on weather to leave the resistance wire or run a new hot feed. Instructions not very clearly written and calling them didn't help. I'm still on factory resistor wire and it seems fine.
John Lebetski
Woodstock, IL
77 Eleganza II
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| Re: Pertronix install on Onan mysteries [message #278918 is a reply to message #278782] |
Tue, 02 June 2015 09:12 |
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RF_Burns
Messages: 2277
Registered: June 2008
Location: S. Ontario, Canada
Karma: 3
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Senior Member |
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Last night the epoxy was setup once again, so I checked the clearences and gave it a try... started right up! WOO HOO!
I believe my issue (after I fixed the magnet polarity issue) was the OFF time on the Pertronix was only ~ 1/16" of flywheel travel. This did not let the coil field fully collapse before the coil had primary current again.
Couple of things I learned:
- Magnet must have its South Pole facing out at the Pertronix pickup.
- Check this by using a compass, North needle must point to the magnet when installed properly.
-Check the best position for the magnet to track across the face.
- You want the longest "OFF" time for the coil as the magnet moves across the face of the sensor.
- I found a difference from 1/16" travel to over 3/8" by moving the magnet to track nearer the outer edge.
My dwell comment should read more like "Duty Cycle". The Pertronix module is ON all the time, except for the short period of time the magnet is passing the module. So this is akin to having the points closed for more than 357 degrees of rotation, then open for less than 3 degrees or 99.3% duty cycle. This would be the same as applying 12V across the coil primary and leaving it there for hours... a very hot coil! On an 8 cylinder with 30 deg of dwell time times 8 cylinders = 240 deg of ON time or 66% duty cycle. The Onan with its shared firing maybe has a dwell of 20 deg or less than 6% duty cycle. So just wondering if a coil designed for a 6% duty cycle going to have a short life at near 100%... consensus says No.
One other interesting fact, Earth's North pole is actually a South Magnetic Pole.
Bruce Hislop
ON Canada
77PB, 455 Dick P. rebuilt, DynamicEFI EBL EFI & ESC.
1 ton front end
http://www.gmcmhphotos.com/photos/showphoto.php?photo=29001
My Staff says I never listen to them, or something like that
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| Re: [GMCnet] Pertronix install on Onan mysteries [message #278920 is a reply to message #278918] |
Tue, 02 June 2015 09:27 |
Mr ERFisher
Messages: 7117
Registered: August 2005
Karma: 2
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Senior Member |
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Just does not matter. Read the instructions
On Tuesday, June 2, 2015, Bruce Hislop wrote:
> Last night the epoxy was setup once again, so I checked the clearences and
> gave it a try... started right up! WOO HOO!
>
> I believe my issue (after I fixed the magnet polarity issue) was the OFF
> time on the Pertronix was only ~ 1/16" of flywheel travel. This did not let
> the coil field fully collapse before the coil had primary current again.
>
> Couple of things I learned:
> - Magnet must have its South Pole facing out at the Pertronix pickup.
> - Check this by using a compass, North needle must point to the magnet
> when installed properly.
>
> -Check the best position for the magnet to track across the face.
> - You want the longest "OFF" time for the coil as the magnet moves
> across the face of the sensor.
> - I found a difference from 1/16" travel to over 3/8" by moving the
> magnet to track nearer the outer edge.
>
> My dwell comment should read more like "Duty Cycle". The Pertronix module
> is ON all the time, except for the short period of time the magnet is
> passing the module. So this is akin to having the points closed for more
> than 357 degrees of rotation, then open for less than 3 degrees or 99.3%
> duty cycle. This would be the same as applying 12V across the coil primary
> and leaving it there for hours... a very hot coil! On an 8 cylinder with 30
> deg of dwell time times 8 cylinders = 240 deg of ON time or 66% duty
> cycle. The Onan with its shared firing maybe has a dwell of 20 deg or less
> than
> 6% duty cycle. So just wondering if a coil designed for a 6% duty cycle
> going to have a short life at near 100%... consensus says No.
>
> One other interesting fact, Earth's North pole is actually a South
> Magnetic Pole.
>
> --
> Bruce Hislop
> ON Canada
> 77PB, 455 Dick P. rebuilt, DynamicEFI EBL EFI & ESC.
> Hubler 1 ton front end
> http://www.gmcmhphotos.com/photos/showphoto.php?photo=29001
> My Staff says I never listen to them, or something like that
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:
> http://temp.gmcnet.org/cgi-bin/mailman/listinfo/gmclist
>
--
Gene Fisher -- 74-23,77PB/ore/ca
“Give a man a fish; you have fed him for today --- give him a URL and
-------
http://gmcmotorhome.info/
Alternator Protection Cable
http://gmcmotorhome.info/APC.html
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| Re: [GMCnet] Pertronix install on Onan mysteries [message #278927 is a reply to message #278926] |
Tue, 02 June 2015 10:25 |
Mr ERFisher
Messages: 7117
Registered: August 2005
Karma: 2
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Senior Member |
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Experience is good
Conclusions are suspect
Be well
Erf
On Tuesday, June 2, 2015, Bruce Hislop wrote:
> Gene,
> Thats fine, sorry I bothered you by sharing my experiences. I shant bother
> anymore..
>
> --
> Bruce Hislop
> ON Canada
> 77PB, 455 Dick P. rebuilt, DynamicEFI EBL EFI & ESC.
> Hubler 1 ton front end
> http://www.gmcmhphotos.com/photos/showphoto.php?photo=29001
> My Staff says I never listen to them, or something like that
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:
> http://temp.gmcnet.org/cgi-bin/mailman/listinfo/gmclist
>
--
Gene Fisher -- 74-23,77PB/ore/ca
“Give a man a fish; you have fed him for today --- give him a URL and
-------
http://gmcmotorhome.info/
Alternator Protection Cable
http://gmcmotorhome.info/APC.html
_______________________________________________
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