Home » Public Forums » GMCnet » Ignition question for Rob.
| Ignition question for Rob. [message #189269] |
Mon, 05 November 2012 18:59  |
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Matt Colie
Messages: 8547
Registered: March 2007
Location: S.E. Michigan
Karma: 7
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Hey Rob,
I know that after they dropped the magneto, Harleys went to a gap that was more like old car (~0.028), but did they ever come up with a better ignition in the later years that could fire plugs a little harder?
If yes, what is the chance that we could plug that onto an Onan as get it to really light the fire?
I have to believe that we can do better than 0.018~0.020.
Matt
Matt & Mary Colie - Chaumière -'73 Glacier 23 - Members GMCMI, GMCGL, GMCES
Electronically Controlled Quiet Engine Cooling Fan with OE Rear Drum Brakes with Applied Control Arms
SE Michigan - Near DTW - Twixt A2 and Detroit
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| Re: [GMCnet] Ignition question for Rob. [message #189295 is a reply to message #189269] |
Tue, 06 November 2012 01:05  |
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USAussie
Messages: 15912
Registered: July 2007
Location: Sydney, Australia
Karma: 6
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Matt,
I haven't played with Harleys since I left Hong Kong in 1999. The hi performance option at that time was to replace the HD waste
spark system with what was called a single fire system. Each cylinder had a dedicated coil. At that time the only system available
was the Crane HI-4 which is what I installed. As you can see the timing for the front and rear cylinders can be set individually. I
can't remember what I set them at any more.
http://www.cranecams.com/uploads/instructions/90004000b.pdf
I couldn't remember what I used to set the plugs at but 0.040 came to mind and when I did a bit of Google research that number was
good.
I don't see how we could come up with a single fire system with the OEM points system, we could with the Pertronics mod by
installing two magnets in the flywheel, - I think?
Regards,
Rob M.
-----Original Message-----
From: Matt Colie
Hey Rob,
I know that after they dropped the magneto, Harleys went to a gap that was more like old car (~0.028), but did they ever come up
with a better ignition in the later years that could fire plugs a little harder?
If yes, what is the chance that we could plug that onto an Onan as get it to really light the fire?
I have to believe that we can do better than 0.018~0.020.
Matt
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Regards,
Rob M. (USAussie)
The Pedantic Mechanic
Sydney, Australia
'75 Avion - AUS - The Blue Streak TZE365V100428
'75 Avion - USA - Double Trouble TZE365V100426
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| Re: Ignition question for Rob. [message #189297 is a reply to message #189269] |
Tue, 06 November 2012 03:07 |
Ken Burton
Messages: 10030
Registered: January 2004
Location: Hebron, Indiana
Karma: 10
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The limiting factor on this whole system is how much current can be pulled across the points at any given time.
Since the points or Pertronix pickup is mounted on the flywheel and not the cam part of the engine you are going to get a trigger on every revolution even though you only need it on every second revolution like most gasoline engines operate.
So what you need to do if you want two coils is to determine how much current the Pertronix will turn off and on and trigger two coils simultaneously if that is within specs. If the Pertronix will not handle the current, then you could use the Pertronix unit it to trigger a higher current SCR or you mount two separate Pertronix units (one for each coil)
I hope this is just an academic exercise since the system runs just fine the way it is once you eliminate the points with a Pertronix unit.
Lawrence Gaskins had a great idea when he came up with it and I do not see any reason to try to improve it.
Ken Burton - N9KB
76 Palm Beach
Hebron, Indiana
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| Re: [GMCnet] Ignition question for Rob. [message #189306 is a reply to message #189269] |
Tue, 06 November 2012 07:02 |
jhbridges
Messages: 8412
Registered: May 2011
Location: Braselton ga
Karma: -74
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Well, if the timing drift of the exxisting points doesn't put you off, anyone's capacitive discharge system would allow you to open the gap out substantially and light the fire with a hell of a snap for relatively cheap. If you want to get away from the pushrod and its attendant slop, you're going to have to put some sort of sensor on the unti to tell where the crankshaft is in its roataion... the Pertronix setup being the current weapon o choise. Now when I get to the Onana in the PB - likely many months yet - I'm going to see what a CDI will do for it since a) I have one kicking around here someplace and B) I'm lazy and that's the quick n dirty way to see how a hot spark will help the genset. I have in the back of my mind an optical sensor because it's easy to iterate, extremely easy to vary the timing, and agaiain I have the pieces-parts to gin one up. It may never happen, but I think it would be preferable to gluing a pickup inside the
flywheel area.
--johnny
'76 23' transmode norris
'76 palm beach
From: Matt Colie <matt7323tze@gmail.com>
To: gmclist@temp.gmcnet.org
Sent: Monday, November 5, 2012 7:59 PM
Subject: [GMCnet] Ignition question for Rob.
Hey Rob,
I know that after they dropped the magneto, Harleys went to a gap that was more like old car (~0.028), but did they ever come up with a better ignition in the later years that could fire plugs a little harder?
If yes, what is the chance that we could plug that onto an Onan as get it to really light the fire?
I have to believe that we can do better than 0.018~0.020.
Matt
--
Matt & Mary Colie
'73 Glacier 23 Chaumière (say show-me-air) Just about as stock as you will find
SE Michigan - Twixt A2 and Detroit
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Foolish Carriage, 76 26' Eleganza(?) with beaucoup mods and add - ons.
Braselton, Ga.
I forgive them all, save those who hurt the dogs. They must answer to me in hell
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| Re: [GMCnet] Ignition question for Rob. [message #189308 is a reply to message #189306] |
Tue, 06 November 2012 07:13 |
Ken Henderson
Messages: 8726
Registered: March 2004
Location: Americus, GA
Karma: 9
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If I still had an Onan, if it didn't have Pertronix, if I wanted to save a
few bucks, and if I wanted to experiment a little, I'd use an HEI module to
drive the coil. I considered it "back when", but never did it.
On the other hand, Johnny, I don't understand your reluctance to use the
Pertronix -- you're going to have to devise a shutter wheel for an optical
trigger, which may be more difficult than mounting a magnet.
JMHO,
Ken H.
Americus, GA
'76 X-Birchaven w/Cad500/Howell EFI+ & EBL
www.gmcwipersetc.com
On Tue, Nov 6, 2012 at 8:02 AM, Johnny Bridges wrote:
> ... It may never happen, but I think it would be preferable to gluing a
> pickup inside the
> flywheel area.
>
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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] Ignition question for Rob. [message #189312 is a reply to message #189308] |
Tue, 06 November 2012 07:36 |
jhbridges
Messages: 8412
Registered: May 2011
Location: Braselton ga
Karma: -74
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Couple of reasons. I got the pieces and I'mfairly familiar with the technology (ever see one of the cartridge players in a radio station with the big wheel? Or an Ampex videor cart player? Full of optical sensors). And all it takes is a piece of flat black around the outside of the flywheel with a small sliver of reflective at the timing point. Move the sliver you've moving the timing. No shutter wheel needed. What you're looking for is the change in reflectivity, and as long as it's consistent you don't care how great it is... you need only a zero crossing. Whatever slop is in the system doesn't change, so it's a 'set and forget' deal just like the magnetic pickup. No flywheel removal necessary, nothing iside the flywheel cavity to come loose and (perhaps) create grief. And plus it's a challenge. Although admittedly, one of the downfalls of the Ampex machine was sensitivity to changing light levels from external sources. Inside
the generator bay under the air shropuds, I don't think this would be a concern.
--johnny
'76 23' transmode norris
'76 palm beach
From: Ken Henderson <hend4800@bellsouth.net>
To: gmclist <gmclist@temp.gmcnet.org>
Sent: Tuesday, November 6, 2012 8:13 AM
Subject: Re: [GMCnet] Ignition question for Rob.
If I still had an Onan, if it didn't have Pertronix, if I wanted to save a
few bucks, and if I wanted to experiment a little, I'd use an HEI module to
drive the coil. I considered it "back when", but never did it.
On the other hand, Johnny, I don't understand your reluctance to use the
Pertronix -- you're going to have to devise a shutter wheel for an optical
trigger, which may be more difficult than mounting a magnet.
JMHO,
Ken H.
Americus, GA
'76 X-Birchaven w/Cad500/Howell EFI+ & EBL
http://www.gmcwipersetc.com/
On Tue, Nov 6, 2012 at 8:02 AM, Johnny Bridges wrote:
> ... It may never happen, but I think it would be preferable to gluing a
> pickup inside the
> flywheel area.
>
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Foolish Carriage, 76 26' Eleganza(?) with beaucoup mods and add - ons.
Braselton, Ga.
I forgive them all, save those who hurt the dogs. They must answer to me in hell
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| Re: [GMCnet] Ignition question for Rob. [message #189318 is a reply to message #189312] |
Tue, 06 November 2012 09:58 |
GMC_LES
Messages: 569
Registered: October 2009
Location: Montreal
Karma: 0
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The biggest problem with the optical sensor idea on an Onan is dirt. Road grime and wet roads would make cleaning the sensor and reflective surface a routine necessity. Magnets can tolerate lots of dirt without any negative effects.
Les Burt
Montreal
On 2012-11-06, at 8:36 AM, Johnny Bridges <jhbridges@ymail.com> wrote:
> Couple of reasons. I got the pieces and I'mfairly familiar with the technology (ever see one of the cartridge players in a radio station with the big wheel? Or an Ampex videor cart player? Full of optical sensors). And all it takes is a piece of flat black around the outside of the flywheel with a small sliver of reflective at the timing point. Move the sliver you've moving the timing. No shutter wheel needed. What you're looking for is the change in reflectivity, and as long as it's consistent you don't care how great it is... you need only a zero crossing. Whatever slop is in the system doesn't change, so it's a 'set and forget' deal just like the magnetic pickup. No flywheel removal necessary, nothing iside the flywheel cavity to come loose and (perhaps) create grief. And plus it's a challenge. Although admittedly, one of the downfalls of the Ampex machine was sensitivity to changing light levels from external sources. Inside
> the generator bay under the air shropuds, I don't think this would be a concern.
>
> --johnny
> '76 23' transmode norris
> '76 palm beach
>
> From: Ken Henderson <hend4800@bellsouth.net>
> To: gmclist <gmclist@temp.gmcnet.org>
> Sent: Tuesday, November 6, 2012 8:13 AM
> Subject: Re: [GMCnet] Ignition question for Rob.
>
> If I still had an Onan, if it didn't have Pertronix, if I wanted to save a
> few bucks, and if I wanted to experiment a little, I'd use an HEI module to
> drive the coil. I considered it "back when", but never did it.
>
> On the other hand, Johnny, I don't understand your reluctance to use the
> Pertronix -- you're going to have to devise a shutter wheel for an optical
> trigger, which may be more difficult than mounting a magnet.
>
> JMHO,
>
> Ken H.
> Americus, GA
> '76 X-Birchaven w/Cad500/Howell EFI+ & EBL
> http://www.gmcwipersetc.com/
>
>
>
> On Tue, Nov 6, 2012 at 8:02 AM, Johnny Bridges wrote:
>
>> ... It may never happen, but I think it would be preferable to gluing a
>> pickup inside the
>> flywheel area.
>>
> _______________________________________________
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Les Burt
Montreal
1975 Eleganza 26ft
A work in Progress
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| Re: [GMCnet] Ignition question for Rob. [message #189320 is a reply to message #189318] |
Tue, 06 November 2012 10:18 |
jhbridges
Messages: 8412
Registered: May 2011
Location: Braselton ga
Karma: -74
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Senior Member |
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I dunno - it's worth a try since it's all kinds of simple to do. The outer edge of the Junkerac flywheel was nicely clean when I was working on it, as was the shroud... indicating on it at least, you could find a location where the thing would stay clean. There's prolly one on an Onan too. Worst case is, take the optical sensor off and put a coil on and put a magnet on the moving part. Or mlount it where the point end moves under it and away....
--johnny
'76 23' transmode norris
'76 palm beach
From: Les Burt <gmc.les@gmail.com>
To: "gmclist@temp.gmcnet.org" <gmclist@temp.gmcnet.org>
Sent: Tuesday, November 6, 2012 10:58 AM
Subject: Re: [GMCnet] Ignition question for Rob.
The biggest problem with the optical sensor idea on an Onan is dirt. Road grime and wet roads would make cleaning the sensor and reflective surface a routine necessity. Magnets can tolerate lots of dirt without any negative effects.
Les Burt
Montreal
On 2012-11-06, at 8:36 AM, Johnny Bridges <jhbridges@ymail.com> wrote:
> Couple of reasons. I got the pieces and I'mfairly familiar with the technology (ever see one of the cartridge players in a radio station with the big wheel? Or an Ampex videor cart player? Full of optical sensors). And all it takes is a piece of flat black around the outside of the flywheel with a small sliver of reflective at the timing point. Move the sliver you've moving the timing. No shutter wheel needed. What you're looking for is the change in reflectivity, and as long as it's consistent you don't care how great it is... you need only a zero crossing. Whatever slop is in the system doesn't change, so it's a 'set and forget' deal just like the magnetic pickup. No flywheel removal necessary, nothing iside the flywheel cavity to come loose and (perhaps) create grief. And plus it's a challenge. Although admittedly, one of the downfalls of the Ampex machine was sensitivity to changing light levels from external sources.
Inside
> the generator bay under the air shropuds, I don't think this would be a concern.
>
> --johnny
> '76 23' transmode norris
> '76 palm beach
>
> From: Ken Henderson <hend4800@bellsouth.net>
> To: gmclist <gmclist@temp.gmcnet.org>
> Sent: Tuesday, November 6, 2012 8:13 AM
> Subject: Re: [GMCnet] Ignition question for Rob.
>
> If I still had an Onan, if it didn't have Pertronix, if I wanted to save a
> few bucks, and if I wanted to experiment a little, I'd use an HEI module to
> drive the coil. I considered it "back when", but never did it.
>
> On the other hand, Johnny, I don't understand your reluctance to use the
> Pertronix -- you're going to have to devise a shutter wheel for an optical
> trigger, which may be more difficult than mounting a magnet.
>
> JMHO,
>
> Ken H.
> Americus, GA
> '76 X-Birchaven w/Cad500/Howell EFI+ & EBL
> http://www.gmcwipersetc.com/
>
>
>
> On Tue, Nov 6, 2012 at 8:02 AM, Johnny Bridges wrote:
>
>> ... It may never happen, but I think it would be preferable to gluing a
>> pickup inside the
>> flywheel area.
>>
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:
> http://temp.gmcnet.org/cgi-bin/mailman/listinfo/gmclist
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:
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Foolish Carriage, 76 26' Eleganza(?) with beaucoup mods and add - ons.
Braselton, Ga.
I forgive them all, save those who hurt the dogs. They must answer to me in hell
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| Re: [GMCnet] Ignition question for Rob. [message #189371 is a reply to message #189308] |
Tue, 06 November 2012 19:43 |
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wally
Messages: 643
Registered: August 2004
Location: Omaha Nebraska
Karma: 5
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Senior Member |
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We experimented with GM DIs and Magnavox waste spark coils driven by 4 pin and 7 pin modules. The modules were triggered by a VRSensor and tab bolted on the Onan flywheel. Found that dwell is way to much and when the modules go into current limiting trying to drive dis coils we got extra random sparks. Hei modules will drive the Onan coil just fine or the DIS coils with a couple ohms ballast resister added but that kind of defeats the purpose. What is really needed is some kind of dwell control to make this work. I have it now on a DIS coil and 2.4 ohms of ballast resistor. Gap is set at original specs.
| Ken Henderson wrote on Tue, 06 November 2012 07:13 |
If I still had an Onan, if it didn't have Pertronix, if I wanted to save a
few bucks, and if I wanted to experiment a little, I'd use an HEI module to
drive the coil. I considered it "back when", but never did it.
On the other hand, Johnny, I don't understand your reluctance to use the
Pertronix -- you're going to have to devise a shutter wheel for an optical
trigger, which may be more difficult than mounting a magnet.
JMHO,
Ken H.
Americus, GA
'76 X-Birchaven w/Cad500/Howell EFI+ & EBL
www.gmcwipersetc.com
On Tue, Nov 6, 2012 at 8:02 AM, Johnny Bridges wrote:
> ... It may never happen, but I think it would be preferable to gluing a
> pickup inside the
> flywheel area.
>
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Wally Anderson
Omaha NE
75 Glenbrook
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| Re: [GMCnet] Ignition question for Rob. [message #189376 is a reply to message #189371] |
Tue, 06 November 2012 20:07 |
Ken Henderson
Messages: 8726
Registered: March 2004
Location: Americus, GA
Karma: 9
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Senior Member |
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Wally,
That's interesting. When I was fooling with Onans and Pertronix, I talked
to an engineer at Pertronix. He expressed some concern that we might get
too much dwell from the the 1181 module we were using and was a little
surprised that we'd had no problems. I guess ignorance is bliss. :-)
Ken H.
On Tue, Nov 6, 2012 at 8:43 PM, Wally Anderson wrote:
>
> We experimented with GM DIs and Magnavox waste spark coils driven by 4
> pin and 7 pin modules. The modules were triggered by a VRSensor and tab
> bolted on the Onan flywheel. Found that dwell is way to much ...
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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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