Home » Public Forums » GMCnet » Back On The Road / Onan MSD Ignition Kit Experience
| Back On The Road / Onan MSD Ignition Kit Experience [message #345345] |
Mon, 15 July 2019 11:50  |
jtfred
Messages: 132
Registered: January 2015
Location: Grand Marais, MN
Karma: 0
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Senior Member |
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I'm back on the road after 3 years in storage. I just got back from a 600 mile weekend with relatives in central MN. I had spent some time going through things to make sure everything was ready for the weekend. We took some short trips to shake it down and I felt that things looked good enough to go. I even got the A/C and cruise working. Within the first 20 miles of leaving home I wasn't able to hold speed going up hills. I figured that it was a fuel filter, but there wasn't a parts store open for a hundred miles so I would get as much speed I could going down (about 55) and limp up the hills (about 30). Sorry if I was holding anyone up on Hwy 61 between Grand Marais and Duluth, MN last Thursday night. I had my son pick up a filter in Duluth and within 20 minutes I was able to go as fast as I needed for the rest of the trip. I had forgotten how fun these things are to drive!
Now that my enthusiasm has been renewed in the old coach I'm wanting to get to a couple of things that I didn't get to already. One thing is getting the Onan running again. Before moving back to MN from GA where I bought the coach I had tried to convert the Onan ignition to a pertronics DIY setup. I was never able to get it going and threw in the towel. I wasn't even able to get it running by converting it back to the original ignition. I gave up and moved on. Now I'm thinking that this is the next project.
I have been thinking about the MSD ignition that JimK is selling, but haven't seen much about it mentioned in this group. Has anyone converted their Onan to this type of ignition? I'm assuming the setup is easier that the DYI approach I was doing previously and it sounds like the spark is much stronger. What do y'all think?
Thanks!
JohnF
Grand Marais, MN
1978 Eleganza
John Fredrikson
Grand Marais, MN
1978 Eleganza
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| Re: [GMCnet] Back On The Road / Onan MSD Ignition Kit Experience [message #345347 is a reply to message #345345] |
Mon, 15 July 2019 12:17  |
jimk
Messages: 6734
Registered: July 2006
Location: Belmont, CA
Karma: 9
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Senior Member |
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John,
The MSD ignition conversion gives it a very positive two sparks on one
stroke and is very reliable.
No other system can do that.
Just noticed it is not on our new site, go to our old one for now.
On Mon, Jul 15, 2019 at 9:51 AM John Fredrikson via Gmclist <
gmclist@list.gmcnet.org> wrote:
> I'm back on the road after 3 years in storage. I just got back from a 600
> mile weekend with relatives in central MN. I had spent some time going
> through things to make sure everything was ready for the weekend. We took
> some short trips to shake it down and I felt that things looked good enough
> to go. I even got the A/C and cruise working. Within the first 20 miles of
> leaving home I wasn't able to hold speed going up hills. I figured that it
> was a fuel filter, but there wasn't a parts store open for a hundred miles
> so I would get as much speed I could going down (about 55) and limp up the
> hills (about 30). Sorry if I was holding anyone up on Hwy 61 between Grand
> Marais and Duluth, MN last Thursday night. I had my son pick up a filter in
> Duluth and within 20 minutes I was able to go as fast as I needed for the
> rest of the trip. I had forgotten how fun these things are to drive!
>
> Now that my enthusiasm has been renewed in the old coach I'm wanting to
> get to a couple of things that I didn't get to already. One thing is getting
> the Onan running again. Before moving back to MN from GA where I bought
> the coach I had tried to convert the Onan ignition to a pertronics DIY
> setup.
> I was never able to get it going and threw in the towel. I wasn't even
> able to get it running by converting it back to the original ignition. I
> gave
> up and moved on. Now I'm thinking that this is the next project.
>
> I have been thinking about the MSD ignition that JimK is selling, but
> haven't seen much about it mentioned in this group. Has anyone converted
> their
> Onan to this type of ignition? I'm assuming the setup is easier that the
> DYI approach I was doing previously and it sounds like the spark is much
> stronger. What do y'all think?
>
> Thanks!
>
> JohnF
> Grand Marais, MN
> 1978 Eleganza
> --
> John Fredrikson
> Fayetteville, GA
> 1978 Eleganza
>
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:
> http://list.gmcnet.org/mailman/listinfo/gmclist_list.gmcnet.org
>
--
Jim Kanomata
Applied/GMC, Newark,CA
jimk@appliedairfilters.com
http://www.appliedgmc.com
1-800-752-7502
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Applied/GMC
jimk@appliedairfilters.com
www.appliedgmc.com
1-800-752-7502
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| Re: [GMCnet] Back On The Road / Onan MSD Ignition Kit Experience [message #345348 is a reply to message #345347] |
Mon, 15 July 2019 12:20 |
jimk
Messages: 6734
Registered: July 2006
Location: Belmont, CA
Karma: 9
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Senior Member |
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http://www.appliedgmc.com/prod.itml/icOid/1380
On Mon, Jul 15, 2019 at 10:17 AM Jim Kanomata wrote:
> John,
> The MSD ignition conversion gives it a very positive two sparks on one
> stroke and is very reliable.
> No other system can do that.
> Just noticed it is not on our new site, go to our old one for now.
>
> On Mon, Jul 15, 2019 at 9:51 AM John Fredrikson via Gmclist gmclist@list.gmcnet.org> wrote:
>
>> I'm back on the road after 3 years in storage. I just got back from a 600
>> mile weekend with relatives in central MN. I had spent some time going
>> through things to make sure everything was ready for the weekend. We took
>> some short trips to shake it down and I felt that things looked good enough
>> to go. I even got the A/C and cruise working. Within the first 20 miles
>> of leaving home I wasn't able to hold speed going up hills. I figured that
>> it
>> was a fuel filter, but there wasn't a parts store open for a hundred
>> miles so I would get as much speed I could going down (about 55) and limp
>> up the
>> hills (about 30). Sorry if I was holding anyone up on Hwy 61 between
>> Grand Marais and Duluth, MN last Thursday night. I had my son pick up a
>> filter in
>> Duluth and within 20 minutes I was able to go as fast as I needed for the
>> rest of the trip. I had forgotten how fun these things are to drive!
>>
>> Now that my enthusiasm has been renewed in the old coach I'm wanting to
>> get to a couple of things that I didn't get to already. One thing is getting
>> the Onan running again. Before moving back to MN from GA where I bought
>> the coach I had tried to convert the Onan ignition to a pertronics DIY
>> setup.
>> I was never able to get it going and threw in the towel. I wasn't even
>> able to get it running by converting it back to the original ignition. I
>> gave
>> up and moved on. Now I'm thinking that this is the next project.
>>
>> I have been thinking about the MSD ignition that JimK is selling, but
>> haven't seen much about it mentioned in this group. Has anyone converted
>> their
>> Onan to this type of ignition? I'm assuming the setup is easier that the
>> DYI approach I was doing previously and it sounds like the spark is much
>> stronger. What do y'all think?
>>
>> Thanks!
>>
>> JohnF
>> Grand Marais, MN
>> 1978 Eleganza
>> --
>> John Fredrikson
>> Fayetteville, GA
>> 1978 Eleganza
>>
>> _______________________________________________
>> GMCnet mailing list
>> Unsubscribe or Change List Options:
>> http://list.gmcnet.org/mailman/listinfo/gmclist_list.gmcnet.org
>>
>
>
> --
> Jim Kanomata
> Applied/GMC, Newark,CA
> jimk@appliedairfilters.com
> http://www.appliedgmc.com
> 1-800-752-7502
>
--
Jim Kanomata
Applied/GMC, Newark,CA
jimk@appliedairfilters.com
http://www.appliedgmc.com
1-800-752-7502
_______________________________________________
GMCnet mailing list
Unsubscribe or Change List Options:
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Jim Kanomata
Applied/GMC
jimk@appliedairfilters.com
www.appliedgmc.com
1-800-752-7502
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| Re: Back On The Road / Onan MSD Ignition Kit Experience [message #345359 is a reply to message #345345] |
Mon, 15 July 2019 15:15 |
jtfred
Messages: 132
Registered: January 2015
Location: Grand Marais, MN
Karma: 0
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Senior Member |
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I had forgotten that when I was working on upgrading to the pertronics ignition I found out that the PO had upgraded to the Onan solid state ignition. I'm not sure of it's condition since at the time I wasn't happy with the operation of the Onan, so It may be faulty, I just can't remember. I think I need to go back to square one and start troubleshooting what I have and go from there. If I do decide to go with the MSD I do still have the original points to use. I guess it's time to dig out the manuals and start troubleshooting.
John
John Fredrikson
Grand Marais, MN
1978 Eleganza
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| Re: Back On The Road / Onan MSD Ignition Kit Experience [message #345362 is a reply to message #345345] |
Mon, 15 July 2019 16:53 |
lqqkatjon
Messages: 2324
Registered: October 2010
Location: St. Cloud, MN
Karma: 5
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Senior Member |
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What year is your coach/onan?
the newer one's have a point system that is pretty easy to deal with. The older point systems for the average person need to be tossed aside. very bad design. I had no issues with my bovee electronic ignition, but you should have a running onan prior to installing that.
spark is pretty simple to get going, I struggle with the carbs. a new coil is reasonable, and easy to troubleshoot. Also want to disconnect the charging circuit if you have not already.
Was a hot weekend, even though the north shore is usually not as bad as central MN this time of year. a GMC trip up the north shore is on my bucket list, but have not found time to do that yet.
Jon Roche
75 palm beach
EBL EFI, manny headers, Micro Level, rebuilt most of coach now.
St. Cloud, MN
http://lqqkatjon.blogspot.com/
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| Re: Back On The Road / Onan MSD Ignition Kit Experience [message #345369 is a reply to message #345362] |
Mon, 15 July 2019 18:50 |
jtfred
Messages: 132
Registered: January 2015
Location: Grand Marais, MN
Karma: 0
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Senior Member |
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lqqkatjon wrote on Mon, 15 July 2019 17:53What year is your coach/onan?
I have a '78.
It was hot last weekend, but I do have my dash air working well thanks to this group. I do what to get the Onan working so I can run the roof air when needed. I'll be working with what I have to try to get it going again before adding any more complexity to the issue.
I'm hoping that we can get it out more often than the past few years. Hopefully I can get out to some of the rallies some time.
John Fredrikson
Grand Marais, MN
1978 Eleganza
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| Re: [GMCnet] Back On The Road / Onan MSD Ignition Kit Experience [message #345382 is a reply to message #345347] |
Mon, 15 July 2019 23:27 |
Ken Burton
Messages: 10030
Registered: January 2004
Location: Hebron, Indiana
Karma: 10
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Senior Member |
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You are dealing with a very slow 1800 rpm 1800 sparks per minute device at low to medium compression levels. It is a wasted spark ignition and fires both plugs at the same time. In a V-8 car the number of sparks per minute would be 7200 per minute at 1800 rpm. There is no acceleration to higher rpm and no spark advance/retard involved on the Onan. It is really a very low tech ignition because that is all that is needed in this application.
The biggest problem with the Onan ignition is the mechanics and wear of the points system. So if you want to improve the ignition, the thing to attack is the reliability and serviceability of the points. So improvement, or elimination of the mechanical points is what you want.
The MSD Capacitive Discharge system addresses a completely different issue which is lower less reliable spark voltage as the engine rpm or load increases. I use to sell CD systems in the 1970's and they did a great job on higher rpm V-8 engines.
The MSD system uses the same mechanical points while increasing the voltage available to the plugs. It also reduces electrical wear on the contact surface of the points but it does nothing to address the mechanical wear issues.
That said, Lawrence Gaskins went after the points reliability and wear issues dofferently by eliminating them. He developed the Petronix add on to address mechanical push rod activated points problems. It does it very well.
I have installed many of these over the years. They just run, and run, and run because there is nothing mechanical to wear and no points to burn.
Gary Bovee took that DIY the we were doing and packaged it with a great set of instructions to make it even easier to install.
So if it were me, I would get the Onan going on the original points system first. Then install the Pertronix unit that you have or order a new one with instructions from Gary Bovee and install it.
Ken Burton - N9KB
76 Palm Beach
Hebron, Indiana
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| Re: [GMCnet] Back On The Road / Onan MSD Ignition Kit Experience [message #345384 is a reply to message #345382] |
Mon, 15 July 2019 23:53 |
James Hupy
Messages: 6806
Registered: May 2010
Karma: -62
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Senior Member |
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Stock points are operated by the camshaft in an ONAN. So, at 1825 RPM, the
points open 912 and 1/2 times. Gary Bovee's ignition kit, being crankshaft
flywheel triggered, does fire once per Revolution.
So, it behooves one to be cognizant of which ignition type you have.
Jim Hupy
Salem, Or
78 GMC ROYALE 403
On Mon, Jul 15, 2019, 9:42 PM Ken Burton via Gmclist <
gmclist@list.gmcnet.org> wrote:
> You are dealing with a very slow 1800 rpm 1800 sparks per minute device at
> low to medium compression levels. It is a wasted spark ignition and fires
> both plugs at the same time. In a V-8 car the number of sparks per minute
> would be 7200 per minute at 1800 rpm. There is no acceleration to higher
> rpm and no spark advance/retard involved on the Onan. It is really a very
> low tech ignition because that is all that is needed in this application.
>
>
> The biggest problem with the Onan ignition is the mechanics and wear of
> the points system. So if you want to improve the ignition, the thing to
> attack is the reliability and serviceability of the points. So
> improvement, or elimination of the mechanical points is what you want.
>
> The MSD Capacitive Discharge system addresses a completely different issue
> which is lower less reliable spark voltage as the engine rpm or load
> increases. I use to sell CD systems in the 1970's and they did a great
> job on higher rpm V-8 engines.
> The MSD system uses the same mechanical points while increasing the
> voltage available to the plugs. It also reduces electrical wear on the
> contact
> surface of the points but it does nothing to address the mechanical wear
> issues.
>
> That said, Lawrence Gaskins went after the points reliability and wear
> issues dofferently by eliminating them. He developed the Petronix add on to
> address mechanical push rod activated points problems. It does it very
> well.
>
> I have installed many of these over the years. They just run, and run,
> and run because there is nothing mechanical to wear and no points to burn.
>
> Gary Bovee took that DIY the we were doing and packaged it with a great
> set of instructions to make it even easier to install.
>
> So if it were me, I would get the Onan going on the original points system
> first. Then install the Pertronix unit that you have or order a new one
> with instructions from Gary Bovee and install it.
> --
> Ken Burton - N9KB
> 76 Palm Beach
> Hebron, Indiana
>
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:
> http://list.gmcnet.org/mailman/listinfo/gmclist_list.gmcnet.org
>
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| Re: Back On The Road / Onan MSD Ignition Kit Experience [message #345390 is a reply to message #345345] |
Tue, 16 July 2019 08:16 |
JohnL455
Messages: 4447
Registered: October 2006
Location: Woodstock, IL
Karma: 12
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Senior Member |
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"different issue which is lower less reliable spark voltage as the engine rpm or load increases". I think it's the other way around Ken. Under high load the mixture is more difficult to gap jump, which causes coil voltage to rise higher before arcing over and dumping the energy from the coil. Once it dumps it dumps but the harder to jump, the higher the secondary voltage rise. Or am I backwards?
High RPM has the problem of incomplete 12 primary saturation, but that does not factor in in a fixed RPM system.
John Lebetski
Woodstock, IL
77 Eleganza II
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| Re: Back On The Road / Onan MSD Ignition Kit Experience [message #345394 is a reply to message #345345] |
Tue, 16 July 2019 09:06 |
jhbridges
Messages: 8412
Registered: May 2011
Location: Braselton ga
Karma: -74
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Senior Member |
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Somehow, that analysis doesn't quite seem right. I'm thinking it's going to light once per rev, as the pistons reach close to TDC. One side will be on the exhaust stroke, and its spark will be wasted. The other side will be ion the compression stroke and its spark will fire that side. This is why a pickoff using a magnet on the flywheel works.
--johnny
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] Back On The Road / Onan MSD Ignition Kit Experience [message #345397 is a reply to message #345394] |
Tue, 16 July 2019 09:32 |
jimk
Messages: 6734
Registered: July 2006
Location: Belmont, CA
Karma: 9
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Senior Member |
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Proof is in the emission test.
When we install the MSD the exaust was at least 30% cleaner.
Done on same engine before and after run with standard ignition.
Why are new Onan units running with high output ignition if it is not
needed????
Have you been around an Onan when it runs?
Smell is sickening.
One factor is poor combustion.
Our unit with the high output does not smell that strong, why.
On Tue, Jul 16, 2019 at 7:07 AM Johnny Bridges via Gmclist <
gmclist@list.gmcnet.org> wrote:
> Somehow, that analysis doesn't quite seem right. I'm thinking it's going
> to light once per rev, as the pistons reach close to TDC. One side will be
> on the exhaust stroke, and its spark will be wasted. The other side will
> be ion the compression stroke and its spark will fire that side. This is
> why a pickoff using a magnet on the flywheel works.
>
> --johnny
> --
> 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
>
>
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:
> http://list.gmcnet.org/mailman/listinfo/gmclist_list.gmcnet.org
>
--
Jim Kanomata
Applied/GMC, Newark,CA
jimk@appliedairfilters.com
http://www.appliedgmc.com
1-800-752-7502
_______________________________________________
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Jim Kanomata
Applied/GMC
jimk@appliedairfilters.com
www.appliedgmc.com
1-800-752-7502
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| Re: [GMCnet] Back On The Road / Onan MSD Ignition Kit Experience [message #345399 is a reply to message #345397] |
Tue, 16 July 2019 09:55 |
jimk
Messages: 6734
Registered: July 2006
Location: Belmont, CA
Karma: 9
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Senior Member |
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https://www.gmcrvparts.com/product-p/gm28-28.044h.01.htm
On Tue, Jul 16, 2019 at 7:32 AM Jim Kanomata wrote:
> Proof is in the emission test.
> When we install the MSD the exaust was at least 30% cleaner.
> Done on same engine before and after run with standard ignition.
> Why are new Onan units running with high output ignition if it is not
> needed????
> Have you been around an Onan when it runs?
> Smell is sickening.
> One factor is poor combustion.
> Our unit with the high output does not smell that strong, why.
>
>
> On Tue, Jul 16, 2019 at 7:07 AM Johnny Bridges via Gmclist gmclist@list.gmcnet.org> wrote:
>
>> Somehow, that analysis doesn't quite seem right. I'm thinking it's going
>> to light once per rev, as the pistons reach close to TDC. One side will be
>> on the exhaust stroke, and its spark will be wasted. The other side will
>> be ion the compression stroke and its spark will fire that side. This is
>> why a pickoff using a magnet on the flywheel works.
>>
>> --johnny
>> --
>> 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
>>
>>
>> _______________________________________________
>> GMCnet mailing list
>> Unsubscribe or Change List Options:
>> http://list.gmcnet.org/mailman/listinfo/gmclist_list.gmcnet.org
>>
> --
> Jim Kanomata
> Applied/GMC, Newark,CA
> jimk@appliedairfilters.com
> http://www.appliedgmc.com
> 1-800-752-7502
>
--
Jim Kanomata
Applied/GMC, Newark,CA
jimk@appliedairfilters.com
http://www.appliedgmc.com
1-800-752-7502
_______________________________________________
GMCnet mailing list
Unsubscribe or Change List Options:
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Jim Kanomata
Applied/GMC
jimk@appliedairfilters.com
www.appliedgmc.com
1-800-752-7502
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| Re: [GMCnet] Back On The Road / Onan MSD Ignition Kit Experience [message #345419 is a reply to message #345345] |
Tue, 16 July 2019 17:41 |
Ken Henderson
Messages: 8726
Registered: March 2004
Location: Americus, GA
Karma: 9
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Senior Member |
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I've no experience with the MSD system, but was one of the earliest to
follow Gaskins' lead with the Pertronix mod. The most dramatic improvement
it exhibited was the dependable, consistent spark creation. With the stock
ignition points, actuated by the camshaft through a straight push rod
through the engine block, the trace shown by a timing light was 1/2"-3/4"
wide blur. That indicates to me that the rod hesitates minutely on its
travel. The primary design engineer on our Onans admitted to us at a rally
that they had considerable trouble with that and had to keep retarding the
timing specification to compensate for it.
With the Pertronix mod, the timing light trace is a single sharp vertical
line -- no blurring whatsoever. That enabled us to advance the timing
several degrees without any detrimental effects. IF I still ran an Onan,
it would run Pertronix.
Ken H.
On Mon, Jul 15, 2019 at 12:51 PM John Fredrikson via Gmclist <
gmclist@list.gmcnet.org> wrote:
> I'm back on the road after 3 years in storage. I just got back from a 600
> mile weekend with relatives in central MN. I had spent some time going
> through things to make sure everything was ready for the weekend. We took
> some short trips to shake it down and I felt that things looked good enough
> to go. I even got the A/C and cruise working. Within the first 20 miles of
> leaving home I wasn't able to hold speed going up hills. I figured that it
> was a fuel filter, but there wasn't a parts store open for a hundred miles
> so I would get as much speed I could going down (about 55) and limp up the
> hills (about 30). Sorry if I was holding anyone up on Hwy 61 between Grand
> Marais and Duluth, MN last Thursday night. I had my son pick up a filter in
> Duluth and within 20 minutes I was able to go as fast as I needed for the
> rest of the trip. I had forgotten how fun these things are to drive!
>
> Now that my enthusiasm has been renewed in the old coach I'm wanting to
> get to a couple of things that I didn't get to already. One thing is getting
> the Onan running again. Before moving back to MN from GA where I bought
> the coach I had tried to convert the Onan ignition to a pertronics DIY
> setup.
> I was never able to get it going and threw in the towel. I wasn't even
> able to get it running by converting it back to the original ignition. I
> gave
> up and moved on. Now I'm thinking that this is the next project.
>
> I have been thinking about the MSD ignition that JimK is selling, but
> haven't seen much about it mentioned in this group. Has anyone converted
> their
> Onan to this type of ignition? I'm assuming the setup is easier that the
> DYI approach I was doing previously and it sounds like the spark is much
> stronger. What do y'all think?
>
> Thanks!
>
> JohnF
> Grand Marais, MN
> 1978 Eleganza
> --
> John Fredrikson
> Fayetteville, GA
> 1978 Eleganza
>
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:
> http://list.gmcnet.org/mailman/listinfo/gmclist_list.gmcnet.org
>
_______________________________________________
GMCnet mailing list
Unsubscribe or Change List Options:
http://list.gmcnet.org/mailman/listinfo/gmclist_list.gmcnet.org
Ken Henderson
Americus, GA
www.gmcwipersetc.com
Large Wiring Diagrams
76 X-Birchaven
76 X-Palm Beach
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| Re: [GMCnet] Back On The Road / Onan MSD Ignition Kit Experience [message #345425 is a reply to message #345384] |
Tue, 16 July 2019 20:55 |
Ken Burton
Messages: 10030
Registered: January 2004
Location: Hebron, Indiana
Karma: 10
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Senior Member |
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James Hupy wrote on Mon, 15 July 2019 23:53Stock points are operated by the camshaft in an ONAN. So, at 1825 RPM, the
points open 912 and 1/2 times. Gary Bovee's ignition kit, being crankshaft
flywheel triggered, does fire once per Revolution.
So, it behooves one to be cognizant of which ignition type you have.
Jim Hupy
Salem, Or
78 GMC ROYALE 403
I am not trying to be pickey here but since the Onan uses a wasted spark ignition with one coil and the plugs wired in series with no distributor, the points open (and close) once per revolution and both plugs fire at the same time. 1800 RPM equals 1800 point openings per minute. One plug ignites fuel/air mix in the first cylinder while at the same time the second filers in the second cylinder where no compressed fuel/ air mix is available. So it accomplishes nothing (hence the term wasted spark). On the next revolution the cylinders and plugs switch roles with the opposite cylinder burning fuel and providing power. Many 2 cylinder engines (Motorcycles, Lawn mowers, etc.) use this simpler wasted spark system.
Ken Burton - N9KB
76 Palm Beach
Hebron, Indiana
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| Re: [GMCnet] Back On The Road / Onan MSD Ignition Kit Experience [message #345427 is a reply to message #345425] |
Tue, 16 July 2019 21:07 |
James Hupy
Messages: 6806
Registered: May 2010
Karma: -62
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Senior Member |
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Bull.
On Tue, Jul 16, 2019, 6:55 PM Ken Burton via Gmclist <
gmclist@list.gmcnet.org> wrote:
> James Hupy wrote on Mon, 15 July 2019 23:53
>> Stock points are operated by the camshaft in an ONAN. So, at 1825 RPM,
> the
>> points open 912 and 1/2 times. Gary Bovee's ignition kit, being
> crankshaft
>> flywheel triggered, does fire once per Revolution.
>> So, it behooves one to be cognizant of which ignition type you have.
>> Jim Hupy
>> Salem, Or
>> 78 GMC ROYALE 403
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> I am not trying to be pickey here but since the Onan uses a wasted spark
> ignition with one coil and the plugs wired in series with no distributor,
> the
> points open (and close) once per revolution and both plugs fire at the
> same time. 1800 RPM equals 1800 point openings per minute. One plug
> ignites
> fuel/air mix in the first cylinder while at the same time the second
> filers in the second cylinder where no compressed fuel/ air mix is
> available. So
> it accomplishes nothing (hence the term wasted spark). On the next
> revolution the cylinders and plugs switch roles with the opposite cylinder
> burning
> fuel and providing power. Many 2 cylinder engines (Motorcycles, Lawn
> mowers, etc.) use this simpler wasted spark system.
>
> --
> Ken Burton - N9KB
> 76 Palm Beach
> Hebron, Indiana
>
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