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Setting timing on Onan [message #283061]

Fri, 24 July 2015 20:06

thainglo

Messages: 132
Registered: March 2015
Location: Iowa

Karma: 2

Senior Member

I'm getting ready to install a Pertronix kit this weekend to eliminate the points as part of my issues with the Onan. Great write ups from Ken H and group on module installation, so feel comfortable digging in there. Have kind of a remedial question that I'm hoping others can help,with...

I want to set my timing at 27 BTDC. I decided to pull my flywheel this afternoon to paint my timing marks so they are clearly visible. The back of my flywheel has TC and 25 marked, so I measured and went a hair farther (about 0.26") to mark 27. Scored with dremel and filled in with white paint. Put some matching marks on the front of the flywheel by the ring teeth for easy reference. I also marked a straight line thru TDC from the mark behind the flywheel.

Here is question: to make timing 27 BTDC, do I align the mark on my flywheel representing 27 BTDC with the TDC on the shroud? When I do this, the TDC on the flywheel is marked with the corresponding factory molding for 27 behind the flywheel. However, there is nothing showing in the timing window...

When I align my flywheel mark with the window to show 27, not much aligns with anything...

Photos of my two scenarios here:
http://www.gmcmhphotos.com/photos/onan/p58561-timing-marks.html

As I said, likely a very remedial question, but I appreciate any guidance. Thanks!

Matt Sladek 1976 Eleganza II Coralville, IA

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Re: Setting timing on Onan [message #283068 is a reply to message #283061]

Fri, 24 July 2015 21:25

Matt Colie

Messages: 8547
Registered: March 2007
Location: S.E. Michigan

Karma: 7

Senior Member

Matt,

I am a little confused here.
Basically - Yes.
If you set it up to fire when your new 27BTDC is at the reference line, that should be correct.
The engine build marks are all for 0° - they are on most engines.
So when you are set at fire point, that is the only thing that will be aligned.

Matt

thainglo wrote on Fri, 24 July 2015 21:06

<snip>
Here is question: to make timing 27 BTDC, do I align the mark on my flywheel representing 27 BTDC with the TDC on the shroud? When I do this, the TDC on the flywheel is marked with the corresponding factory molding for 27 behind the flywheel. However, there is nothing showing in the timing window...

When I align my flywheel mark with the window to show 27, not much aligns with anything...

Photos of my two scenarios here:
http://www.gmcmhphotos.com/photos/onan/p58561-timing-marks.html

As I said, likely a very remedial question, but I appreciate any guidance. Thanks!

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] Setting timing on Onan [message #283084 is a reply to message #283061]

Sat, 25 July 2015 04:46

Mr ERFisher

Messages: 7117
Registered: August 2005

Karma: 2

Senior Member

I bought two of bovees kits
http://www.bdub.net/bovee/BoveeProducts.pdf
They come with perfect instructions and parts

On Friday, July 24, 2015, Matt Sladek wrote:

> I'm getting ready to install a Pertronix kit this weekend to eliminate the
> points as part of my issues with the Onan. Great write ups from Ken H and
> group on module installation, so feel comfortable digging in there. Have
> kind of a remedial question that I'm hoping others can help,with...
>
> I want to set my timing at 27 BTDC. I decided to pull my flywheel this
> afternoon to paint my timing marks so they are clearly visible. The back of
> my
> flywheel has TC and 25 marked, so I measured and went a hair farther
> (about 0.26") to mark 27. Scored with dremel and filled in with white
> paint. Put
> some matching marks on the front of the flywheel by the ring teeth for
> easy reference. I also marked a straight line thru TDC from the mark behind
> the
> flywheel.
>
> Here is question: to make timing 27 BTDC, do I align the mark on my
> flywheel representing 27 BTDC with the TDC on the shroud? When I do this,
> the
> TDC on the flywheel is marked with the corresponding factory molding for
> 27 behind the flywheel. However, there is nothing showing in the timing
> window...
>
> When I align my flywheel mark with the window to show 27, not much aligns
> with anything...
>
> Photos of my two scenarios here:
> http://www.gmcmhphotos.com/photos/onan/p58561-timing-marks.html
>
> As I said, likely a very remedial question, but I appreciate any guidance.
> Thanks!
> --
> Matt Sladek
> 1976 Eleganza II
> Coralville, IA
>
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:
> http://list.gmcnet.org/mailman/listinfo/gmclist_list.gmcnet.org
>

--
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: Setting timing on Onan [message #283088 is a reply to message #283061]

Sat, 25 July 2015 07:17

thainglo

Messages: 132
Registered: March 2015
Location: Iowa

Karma: 2

Senior Member

Thanks Matt. Pretty sure I am overthinking the whole issue. Hope to get it mounted up this weekend and test it out.

Matt Sladek 1976 Eleganza II Coralville, IA

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Re: [GMCnet] Setting timing on Onan [message #283147 is a reply to message #283084]

Sat, 25 July 2015 20:26

rjw

Messages: 697
Registered: September 2005

Karma: 4

Senior Member

Mr ERFisher wrote on Sat, 25 July 2015 05:46

I bought two of bovees kits
http://www.bdub.net/bovee/BoveeProducts.pdf
They come with perfect instructions and parts

I am also installing the pertronix setup this weekend. Most all of the instructions I've seen, including what I saw of the Bovee kit, reference timing markings on the inside of the flywheel cover. Well my Onan does not have any such markings and from the pictures, it appears to me that Matt does not have them either. That makes finding the correct location of TDC and 27 degrees BTDC a bit of a challenge to locate precisely. I resorted to my timing light to find the correct locations.

The Bovee instructions are perfect if you have the timing marks inside the cover. If that is not the case, it is a challenge as Matt and I have found out.

Richard
76 Palm Beach
SE Michigan
www.PalmBeachGMC.com

Roller Cam 455, TBI+EBL, 3.42 FD, 4 Bag, Macerator, Lenzi (brakes, vacuum system, front end stuff), Manny Tranny, vacuum step, Tankless + OEM water heaters.

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Re: [GMCnet] Setting timing on Onan [message #283172 is a reply to message #283061]

Sun, 26 July 2015 05:07

USAussie

Messages: 15912
Registered: July 2007
Location: Sydney, Australia

Karma: 6

Senior Member

Matt,

Please look at MM X-7525 / Section 24C - Onan Motor Generator / Page 24C-27 - 28 / Ignition and Battery Charging System

Note Figure 40 - Timing Access Hole Location

The timing mark is on the back side of the flywheel and according to the MM:

TIMING PROCEDURE (ENGINE RUNNING - HOT SETTING) (6KW)

1. To check the ignition timing with unit running, use a timing light. Connect the timing light according to its manufacturer's
instructions. Either spark plug can be used as they fire simultaneously.

2. A small hole on the rear portion of blower housing provides an access to view timing marks (See figure 40). Two marks are
provided; one for T|C (top center) and one for 2|0 (20° BTC).

3. Start the engine and check the timing. The 2|0 mark on the flywheel should line up in the middle of the hole.

4. Replace breaker box cover and any other hardware removed from engine.

If you rotate the flywheel clockwise (facing the flywheel) and watch the Timing Access Hole for the marks on the back of the
flywheel. The as you rotate the flywheel the first mark you see will be the 20° BTC mark, the second is TDC.

Regards,
Rob M.
The Pedantic Mechanic

-----Original Message-----
From: Matt Sladek

I'm getting ready to install a Pertronix kit this weekend to eliminate the points as part of my issues with the Onan. Great write
ups from Ken H and group on module installation, so feel comfortable digging in there. Have kind of a remedial question that I'm
hoping others can help,with...

I want to set my timing at 27 BTDC. I decided to pull my flywheel this afternoon to paint my timing marks so they are clearly
visible. The back of my flywheel has TC and 25 marked, so I measured and went a hair farther (about 0.26") to mark 27. Scored with
dremel and filled in with white paint. Putsome matching marks on the front of the flywheel by the ring teeth for easy reference. I
also marked a straight line thru TDC from the mark behind the flywheel.

Here is question: to make timing 27 BTDC, do I align the mark on my flywheel representing 27 BTDC with the TDC on the shroud? When
I do this, the TDC on the flywheel is marked with the corresponding factory molding for 27 behind the flywheel. However, there is
nothing showing in the timing window...

When I align my flywheel mark with the window to show 27, not much aligns with anything...

Photos of my two scenarios here:
http://www.gmcmhphotos.com/photos/onan/p58561-timing-marks.html

As I said, likely a very remedial question, but I appreciate any guidance. Thanks!
--
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: [GMCnet] Setting timing on Onan [message #283173 is a reply to message #283147]

Sun, 26 July 2015 05:35

Mr ERFisher

Messages: 7117
Registered: August 2005

Karma: 2

Senior Member

I think if you had the kit, you would see how to do it!!!

On Saturday, July 25, 2015, RJW wrote:

> Mr ERFisher wrote on Sat, 25 July 2015 05:46
>> I bought two of bovees kits
>> http://www.bdub.net/bovee/BoveeProducts.pdf
>> They come with perfect instructions and parts
>
>
> I am also installing the pertronix setup this weekend. Most all of the
> instructions I've seen, including what I saw of the Bovee kit, reference
> timing markings on the inside of the flywheel cover. Well my Onan does
> not have any such markings and from the pictures, it appears to me that Matt
> does not have them either. That makes finding the correct location of TDC
> and 27 degrees BTDC a bit of a challenge to locate precisely. I resorted
> to my timing light to find the correct locations.
>
> The Bovee instructions are perfect if you have the timing marks inside the
> cover. If that is not the case, it is a challenge as Matt and I have found
> out.
> --
> Richard
> 76 Palm Beach
> SE Michigan
> www.PalmBeachGMC.com
>
>
> Coop Roller Cam 455, Howell TBI + EBL, 3.42 FD, Quadra Bag, Macerator,
> Manny Tranny etc.
>
>
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:
> http://list.gmcnet.org/mailman/listinfo/gmclist_list.gmcnet.org
>

--
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] Setting timing on Onan [message #283176 is a reply to message #283147]

Sun, 26 July 2015 06:44

thainglo

Messages: 132
Registered: March 2015
Location: Iowa

Karma: 2

Senior Member

Richard - check behind the flywheel and you should see marks mounted to the front of the shroud. I didn't see them until I pulled my flywheel to clean up and paint the timing marks visible through the small hole on back of shroud.

To see, you might need a flashlight. Looking down at the flywheel from about 11 o'clock position, check between the cooling vanes. There is a series of lines radiating out with timing marks. You can line the TDC mark cut into flywheel (look for dimple along ring gear) with those lines.

Since I pulled the flywheel (was really easy, just a longer crowbar to stop the flywheel from turning braced against the ground and a gear puller) I wire brushed and painted he timing marks on the back, plus scribed and painted a line representing 27 degrees or so. I also used a sharpie and drew a line on the shroud corresponding with TDC as shown on the timing marks on the generator itself. These series of marks made it really easy to see wat timing I was getting.

If you check my picture here (http://www.gmcmhphotos.com/photos/onan/p58561-timing-marks.html), my description might make more sense. The rightmost mark on the flywheel is 27 degrees, aligned with the sharpie for TDC. It is also about this angle that you'd want to look down at the flywheel to see the molded marks as well.

Hope that helps and have fun with the project! I'm wrapping mine up today (hopefully). Getting too hot in the afternoon to do any work outside.

Matt Sladek 1976 Eleganza II Coralville, IA

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Re: [GMCnet] Setting timing on Onan [message #283193 is a reply to message #283176]

Sun, 26 July 2015 10:03

gcbgold

Messages: 60
Registered: August 2012

Karma: -1

Member

Matt,

You are correct there is only one mark on the flywheel TDC. In my Kit
"Bovee's Electronic Ignition Kit" I provide instructions as well as timing
tape for the scroll plate to address the issue of setting the timing
correctly.

Gary Bovee
Red Bluff, CA
1978 Royale

> _______________________________________________
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>
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Re: [GMCnet] Setting timing on Onan [message #283208 is a reply to message #283193]

Sun, 26 July 2015 14:22

USAussie

Messages: 15912
Registered: July 2007
Location: Sydney, Australia

Karma: 6

Senior Member

Gary,

I'M CONFUSED!

Are you saying the following is incorrect?

Please look at MM X-7525 / Section 24C - Onan Motor Generator / Page 24C-27 - 28 / Ignition and Battery Charging System

Note Figure 40 - Timing Access Hole Location

The timing mark is on the back side of the flywheel and according to the MM:

TIMING PROCEDURE (ENGINE RUNNING - HOT SETTING) (6KW)

1. To check the ignition timing with unit running, use a timing light. Connect the timing light according to its manufacturer's
instructions. Either spark plug can be used as they fire simultaneously.

2. A small hole on the rear portion of blower housing provides an access to view timing marks (See figure 40). Two marks are
provided; one for T | C (top center) and one for 2 | 0 (20° BTC).

3. Start the engine and check the timing. The 2 | 0 mark on the flywheel should line up in the middle of the hole.

4. Replace breaker box cover and any other hardware removed from engine.

If you rotate the flywheel clockwise (facing the flywheel) and watch the Timing Access Hole for the marks on the back of the
flywheel. The as you rotate the flywheel the first mark you see will be the 20° BTC mark, the second is TDC.

Regards,
Rob M.
The Pedantic Mechanic

-----Original Message-----
From: Gary Bovee

Matt,

You are correct there is only one mark on the flywheel TDC. In my Kit
"Bovee's Electronic Ignition Kit" I provide instructions as well as timing
tape for the scroll plate to address the issue of setting the timing
correctly.

Gary

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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: [GMCnet] Setting timing on Onan [message #283217 is a reply to message #283208]

Sun, 26 July 2015 16:15

rjw

Messages: 697
Registered: September 2005

Karma: 4

Senior Member

USAussie wrote on Sun, 26 July 2015 15:22

Gary,

I'M CONFUSED!

Are you saying the following is incorrect?

2. A small hole on the rear portion of blower housing provides an access to view timing marks (See figure 40). Two marks are
provided; one for T | C (top center) and one for 2 | 0 (20° BTC).

Rob M.
The Pedantic Mechanic

-----Original Message-----
From: Gary Bovee

Matt,

You are correct there is only one mark on the flywheel TDC. In my Kit
"Bovee's Electronic Ignition Kit" I provide instructions as well as timing
tape for the scroll plate to address the issue of setting the timing
correctly.

Gary

To further complicate things...I just had my flywheel out and cleaned up. It has 2 marks. One marked T|C and the other is marked 2|5 which I assume is 25 degrees BTDC. So the manual is wrong?

Richard
76 Palm Beach
SE Michigan
www.PalmBeachGMC.com

Roller Cam 455, TBI+EBL, 3.42 FD, 4 Bag, Macerator, Lenzi (brakes, vacuum system, front end stuff), Manny Tranny, vacuum step, Tankless + OEM water heaters.

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Re: [GMCnet] Setting timing on Onan [message #283218 is a reply to message #283217]

Sun, 26 July 2015 16:45

Ken Burton

Messages: 10030
Registered: January 2004
Location: Hebron, Indiana

Karma: 10

Senior Member

They all have TDC and I have seen 25 and 22 marked on them also. Now Gary says he has one with no BTDC mark. So that makes 3 variations verified. The retired Onan engineer that I talked to years ago said they played with several different timing values to eliminate the inconsistent push rod points system problem. They were getting occasional warranty engine replacements due to detonation. That is why they retarded the value several times. This will not a problem with the Pertronix installed.

Ken Burton - N9KB
76 Palm Beach
Hebron, Indiana

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Re: [GMCnet] Setting timing on Onan [message #283219 is a reply to message #283208]

Sun, 26 July 2015 18:01

Gary Bovee

Messages: 177
Registered: August 2008

Karma: 0

Senior Member

Rob,

Yes the MM info you listed is not applicable to Matt's Onan. The picture Matt previously posted shows only a notch in the flywheel and no hole in the back of the scroll plate as referred to in the MM info you listed. From my experience I am familiar with the picture Matt posted and to my knowledge that is a 4kw Onan. There is a plug in the flywheel cover that is normally removed so both the flywheel notch and the mark on the scroll plate can be seen for setting the timing.

Gary Bovee
Red Bluff, CA
1978 Royale
www.gmcidiotsguide.com
Free "Internet Idiot's Guide for GMC MotorHome Information"
For MAC, iPad & iPod users - http://iTunes.apple.com/us/book/internet-idiots-guide-for/id623353780?mt=11

> On Jul 26, 2015, at 12:22 PM, Robert Mueller wrote:
>
> Gary,
>
> I'M CONFUSED!
>
> Are you saying the following is incorrect?
>
> Please look at MM X-7525 / Section 24C - Onan Motor Generator / Page 24C-27 - 28 / Ignition and Battery Charging System
>
> Note Figure 40 - Timing Access Hole Location
>
> The timing mark is on the back side of the flywheel and according to the MM:
>
> TIMING PROCEDURE (ENGINE RUNNING - HOT SETTING) (6KW)
>
> 1. To check the ignition timing with unit running, use a timing light. Connect the timing light according to its manufacturer's
> instructions. Either spark plug can be used as they fire simultaneously.
>
> 2. A small hole on the rear portion of blower housing provides an access to view timing marks (See figure 40). Two marks are
> provided; one for T | C (top center) and one for 2 | 0 (20° BTC).
>
> 3. Start the engine and check the timing. The 2 | 0 mark on the flywheel should line up in the middle of the hole.
>
> 4. Replace breaker box cover and any other hardware removed from engine.
>
> If you rotate the flywheel clockwise (facing the flywheel) and watch the Timing Access Hole for the marks on the back of the
> flywheel. The as you rotate the flywheel the first mark you see will be the 20° BTC mark, the second is TDC.
>
> Regards,
> Rob M.
> The Pedantic Mechanic
>
>
> -----Original Message-----
> From: Gary Bovee
>
> Matt,
>
> You are correct there is only one mark on the flywheel TDC. In my Kit
> "Bovee's Electronic Ignition Kit" I provide instructions as well as timing
> tape for the scroll plate to address the issue of setting the timing
> correctly.
>
> Gary
>
>
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:
> http://list.gmcnet.org/mailman/listinfo/gmclist_list.gmcnet.org

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Re: [GMCnet] Setting timing on Onan [message #283220 is a reply to message #283219]

Sun, 26 July 2015 18:23

Dennis S

Messages: 3046
Registered: November 2005

Karma: 2

Senior Member

Gary et al

Here is a photo of the timing mark on my 4kw. It is in an early 73 coach.

http://www.gmcmhphotos.com/photos/pertronix-install-4kw-2c-73-gmc/p37949-pertronix2-003.html

Dennis

Gary Bovee wrote on Sun, 26 July 2015 18:01

Rob,

Yes the MM info you listed is not applicable to Matt's Onan. The picture Matt previously posted shows only a notch in the flywheel and no hole in the back of the scroll plate as referred to in the MM info you listed. From my experience I am familiar with the picture Matt posted and to my knowledge that is a 4kw Onan. There is a plug in the flywheel cover that is normally removed so both the flywheel notch and the mark on the scroll plate can be seen for setting the timing.

Gary Bovee
Red Bluff, CA
1978 Royale
www.gmcidiotsguide.com
Free "Internet Idiot's Guide for GMC MotorHome Information"
For MAC, iPad & iPod users - http://iTunes.apple.com/us/book/internet-idiots-guide-for/id623353780?mt=11

> On Jul 26, 2015, at 12:22 PM, Robert Mueller wrote:
>
> Gary,
>
> I'M CONFUSED!
>
> Are you saying the following is incorrect?
>
> Please look at MM X-7525 / Section 24C - Onan Motor Generator / Page 24C-27 - 28 / Ignition and Battery Charging System
>
> Note Figure 40 - Timing Access Hole Location
>
> The timing mark is on the back side of the flywheel and according to the MM:
>
> TIMING PROCEDURE (ENGINE RUNNING - HOT SETTING) (6KW)
>
> 1. To check the ignition timing with unit running, use a timing light. Connect the timing light according to its manufacturer's
> instructions. Either spark plug can be used as they fire simultaneously.
>
> 2. A small hole on the rear portion of blower housing provides an access to view timing marks (See figure 40). Two marks are
> provided; one for T | C (top center) and one for 2 | 0 (20° BTC).
>
> 3. Start the engine and check the timing. The 2 | 0 mark on the flywheel should line up in the middle of the hole.
>
> 4. Replace breaker box cover and any other hardware removed from engine.
>
> If you rotate the flywheel clockwise (facing the flywheel) and watch the Timing Access Hole for the marks on the back of the
> flywheel. The as you rotate the flywheel the first mark you see will be the 20° BTC mark, the second is TDC.
>
> Regards,
> Rob M.
> The Pedantic Mechanic
>
>
> -----Original Message-----
> From: Gary Bovee
>
> Matt,
>
> You are correct there is only one mark on the flywheel TDC. In my Kit
> "Bovee's Electronic Ignition Kit" I provide instructions as well as timing
> tape for the scroll plate to address the issue of setting the timing
> correctly.
>
> Gary
>
>
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:
> http://list.gmcnet.org/mailman/listinfo/gmclist_list.gmcnet.org

_______________________________________________
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Dennis S
73 Painted Desert 230
Memphis TN Metro

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Re: [GMCnet] Setting timing on Onan [message #283228 is a reply to message #283217]

Sun, 26 July 2015 19:08

USAussie

Messages: 15912
Registered: July 2007
Location: Sydney, Australia

Karma: 6

Senior Member

Richard,

Are the marks on the back side of the flywheel visible through a hole in the shroud?

Yes, it appears the 2 | 0 stated in the MM is incorrect.

Regards,
Rob M.
The Pedantic Mechanic

-----Original Message-----
From: RJW

To further complicate things...I just had my flywheel out and cleaned up. It has 2 marks. One marked T|C and the other is marked
2|5 which I assume is 25 degrees BTDC. So the manual is wrong?

Richard

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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: [GMCnet] Setting timing on Onan [message #283230 is a reply to message #283219]

Sun, 26 July 2015 19:25

USAussie

Messages: 15912
Registered: July 2007
Location: Sydney, Australia

Karma: 6

Senior Member

Gary,

I think we might be getting people mixed up:

Matt Colie= '73 Glacier 23
Matt Sladek = 1976 Eleganza

MattS is the guy that asked about the timing and since he has a '76 Eleganza I assumed it was a 6Kw Onan. He noted; "When I align my
flywheel mark with the window to show 27, not much aligns with anything..."

MM X-7525 / Section 24C - Onan Motor Generator / Page 24C-27 & 28 / Ignition and Battery Charging System

TIMING PROCEDURE (ENGINE RUNNING - HOT SETTING) (4KW)

1. To check the ignition timing with unit running use a timing light. Connect the timing light according to its manufacturer's
instructions. Either spark plug can be used as they fire simultaneously.

2. Remove the dot button on blower housing to provide an access to view timing marks (See figure 40).

3. Start the engine and check the timing. The mark on the flywheel should line up with the 21° mark on the cover.

4. Install dot button, breaker box cover and any other hardware removed from engine.

Regards,
Rob M.

The information above agrees with this photo:

http://www.gmcmhphotos.com/photos/pertronix-install-4kw-2c-73-gmc/p37949-pertronix2-003.html

-----Original Message-----
From: Gmclist [mailto:gmclist-bounces@list.gmcnet.org] On Behalf Of gary.bovee@gmcidiotsguide.com
Sent: Monday, July 27, 2015 9:02 AM
To: gmclist@list.gmcnet.org
Subject: Re: [GMCnet] Setting timing on Onan

Rob,

Yes the MM info you listed is not applicable to Matt's Onan. The picture Matt previously posted shows only a notch in the flywheel
and no hole in the back of the scroll plate as referred to in the MM info you listed. From my experience I am familiar with the
picture Matt posted and to my knowledge that is a 4kw Onan. There is a plug in the flywheel cover that is normally removed so both
the flywheel notch and the mark on the scroll plate can be seen for setting the timing.

Gary Bovee
Red Bluff, CA
1978 Royale
www.gmcidiotsguide.com
Free "Internet Idiot's Guide for GMC MotorHome Information"
For MAC, iPad & iPod users - http://iTunes.apple.com/us/book/internet-idiots-guide-for/id623353780?mt=11

> On Jul 26, 2015, at 12:22 PM, Robert Mueller wrote:
>
> Gary,
>
> I'M CONFUSED!
>
> Are you saying the following is incorrect?
>
> Please look at MM X-7525 / Section 24C - Onan Motor Generator / Page 24C-27 - 28 / Ignition and Battery Charging System
>
> Note Figure 40 - Timing Access Hole Location
>
> The timing mark is on the back side of the flywheel and according to the MM:
>
> TIMING PROCEDURE (ENGINE RUNNING - HOT SETTING) (6KW)
>
> 1. To check the ignition timing with unit running, use a timing light. Connect the timing light according to its manufacturer's
> instructions. Either spark plug can be used as they fire simultaneously.
>
> 2. A small hole on the rear portion of blower housing provides an access to view timing marks (See figure 40). Two marks are
> provided; one for T | C (top center) and one for 2 | 0 (20° BTC).
>
> 3. Start the engine and check the timing. The 2 | 0 mark on the flywheel should line up in the middle of the hole.
>
> 4. Replace breaker box cover and any other hardware removed from engine.
>
> If you rotate the flywheel clockwise (facing the flywheel) and watch the Timing Access Hole for the marks on the back of the
> flywheel. The as you rotate the flywheel the first mark you see will be the 20° BTC mark, the second is TDC.
>
> Regards,
> Rob M.
> The Pedantic Mechanic
>
>
> -----Original Message-----
> From: Gary Bovee
>
> Matt,
>
> You are correct there is only one mark on the flywheel TDC. In my Kit
> "Bovee's Electronic Ignition Kit" I provide instructions as well as timing
> tape for the scroll plate to address the issue of setting the timing
> correctly.
>
> Gary
>
>
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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: [GMCnet] Setting timing on Onan [message #283233 is a reply to message #283228]

Sun, 26 July 2015 20:09

rjw

Messages: 697
Registered: September 2005

Karma: 4

Senior Member

USAussie wrote on Sun, 26 July 2015 20:08

Richard,

Are the marks on the back side of the flywheel visible through a hole in the shroud?

Yes, it appears the 2 | 0 stated in the MM is incorrect.

Regards,
Rob M.
The Pedantic Mechanic

-----Original Message-----
From: RJW

To further complicate things...I just had my flywheel out and cleaned up. It has 2 marks. One marked T|C and the other is marked.

2|5 which I assume is 25 degrees BTDC. So the manual is wrong?

Richard

Rob,

Yes both marks are visible in the hole. Both T|C and 2|5 after I cleaned and painted them with white paint.

Makes sense to me that there is variability to these settings according to what Ken Burton remarked.

I did not know there was a plug installed originally that covered the timing hole. Mine had already vanished by the time I got my GMC 17 years ago.

Richard
76 Palm Beach
SE Michigan
www.PalmBeachGMC.com

Roller Cam 455, TBI+EBL, 3.42 FD, 4 Bag, Macerator, Lenzi (brakes, vacuum system, front end stuff), Manny Tranny, vacuum step, Tankless + OEM water heaters.

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Re: [GMCnet] Setting timing on Onan [message #283235 is a reply to message #283230]

Sun, 26 July 2015 20:14

thainglo

Messages: 132
Registered: March 2015
Location: Iowa

Karma: 2

Senior Member

Haven't seen so much name confusion since I was in high school a couple decades ago and there were four Matts in my class of 36!

Rob is right, mine is a 76 with 6kw. Has the timing hole in back and the 2 | 5. Mark on back.

Got everything reassembled today. Have a little stronger spark but still having some issues getting up to full rpm.

More to follow.

Matt Sladek 1976 Eleganza II Coralville, IA

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