| [GMCnet] Onan Pertronix Upgrade... [message #116961] |
Mon, 28 February 2011 14:43  |
kelvin
Messages: 608
Registered: February 2004
Location: Eugene, OR
Karma: 0
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Senior Member |
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Couple of questions...
The 4Kw in my 230 has two timing marks on the back shroud. One is TDC
and one is 21° BTDC. When I install the Pertonix sensor I figured to
set the timing at 21° but the manuals I've seen say 20° or 25°.
Question: Would there be any point in changing the timing? To what?
I've seen reference to that but don't remember anyone posting timing
numbers. Advancing the timing as far as possible is a good thing in a
car. More advance be good for an Onan?
I've torn the Barbarian down quite a ways. Starter is off (bracket is
in good shape) and I removed the Oil Filter adaptor. Both bolts were
pretty loose. I think that's where my oil leak was coming from.
Question: I see "copper" washers under a number of bolts and nuts. No
lock washers. What's the deal with those? Are they some form of lock
washer? Are they there to avoid electrolysis between aluminum castings
and steel hardware?
I'm adding lock washers and Blue Loctite, just because...
TIA,
Kelvin
'73 23' in Eugene, OR
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| Re: [GMCnet] Onan Pertronix Upgrade... [message #116968 is a reply to message #116961] |
Mon, 28 February 2011 16:10  |
Ken Burton
Messages: 10030
Registered: January 2004
Location: Hebron, Indiana
Karma: 10
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Here is the story on the timing. The Onan runs at a static speed (1800 rpm) and only has one static timing setting unlike other engines that we are use to which vary timing by RPM and load.
I talked to a retired Onan engineer a few years back. He told me that the ONAN 2 cylinder air cooled engine could run at 1800 RPM with 30 degrees BTDC with no problems. The problem that they had was the pushrod arrangement that runs the points. That arrangement did not provide a stable point opening (timing) in some cases. So they specified the timing at a retarded value of 25 degrees.
Then they had a few engines come back (under warranty) with holes burned in the pistons from detonation. They determined it was the points mechanics causing the problem. The fix was to retard the timing specification some more. They went through this operation several times again when still more engines came back. They finally settled at 20 or 21 degrees BTDC. So depending on when your engine was made or the book you are reading was printed you will see several different timing numbers specified.
After you install the Pertronix unit your timing will be rock solid since the trigger is off of the flywheel instead of that cam and push rod arrangement. With the Pertronix you can advance your timing back to a respectable number. I set mine to a conservative 26 to 27 degrees. You have to be careful going too far. If you do go to far you will have starting problems with the cylinder actually firing before it reaches TDC. Also you can see detonation problems under heavy loads and burned pistons.
The above statement does not all apply to the Onan solid state points conversion as it still uses the pushrod / cam arrangement for a trigger.
Ken Burton - N9KB
76 Palm Beach
Hebron, Indiana
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| Re: [GMCnet] Onan Pertronix Upgrade... [message #116974 is a reply to message #116961] |
Mon, 28 February 2011 16:51 |
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Matt Colie
Messages: 8547
Registered: March 2007
Location: S.E. Michigan
Karma: 7
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| Kelvin Dietz wrote on Mon, 28 February 2011 15:43 |
Couple of questions...
The 4Kw in my 230 has two timing marks on the back shroud. One is TDC and one is 21° BTDC. When I install the Pertonix sensor I figured to set the timing at 21° but the manuals I've seen say 20° or 25°.
Question: Would there be any point in changing the timing? To what?
I've seen reference to that but don't remember anyone posting timing numbers. Advancing the timing as far as possible is a good thing in a car. More advance be good for an Onan?
I've torn the Barbarian down quite a ways. Starter is off (bracket is in good shape) and I removed the Oil Filter adaptor. Both bolts were pretty loose. I think that's where my oil leak was coming from.
Question: I see "copper" washers under a number of bolts and nuts. No lock washers. What's the deal with those? Are they some form of lock washer? Are they there to avoid electrolysis between aluminum castings and steel hardware?
I'm adding lock washers and Blue Loctite, just because...
TIA,
Kelvin
'73 23' in Eugene, OR
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Kelvin,
To date, I have been into several Onan BFs (4Kw). All have had the oil filter adapter loose and leaking. Once I replaced the gaskets and the leaking pressure switch, it became so dry that rust is now an issue.
The copper washers under some fasteners are there because those are tapped into oiled spaces and that washer is the seal. Do not use a lock washer in those places as that is a guaranteed leak through the washer split. If you can not get more soft copper washers, use flat steel washers and RTV or teflon thread sealer under the head ans washer and get them all tight before the RTV can cure.
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] Onan Pertronix Upgrade... [message #116979 is a reply to message #116977] |
Mon, 28 February 2011 17:36 |
James Hupy
Messages: 6806
Registered: May 2010
Karma: -62
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Senior Member |
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Kelvin, the points pushrod is a reinforced fiber material kinda like circuit
boards used to be made out of before they switched to epoxys. The pushrod
wears, gets shorter, and the timing gets later and later as it wears. When
you have the magnet secured to the flywheel, and the module secured on a
bracket, whatever you set it at remains unchanged until module failure or
the magnet falls off, which is a long long time. 55 degrees is a whole lot
of advance for something running 1825 RPM.
Jim Hupy
Salem, Or
78 GMC Royale 403
On Mon, Feb 28, 2011 at 3:08 PM, Kelvin Dietz <kelvin@datsuns.com> wrote:
> FWIW, I checked the timing on my 4Kw before taking touching anything.
> It was about 55°BTDC.
> Checked it twice... from both cylinders. 55°. And the thing actually
> ran pretty well.
>
> Set the flywheel to the 21° timing mark and turned the Allen bolt on the
> points until I had the timing at 21°. Point gap was a few thou under
> .020 but pretty close.
>
> Still ran about the same, though. And the timing marks were fairly
> steady at 55° and 21°.
>
> You just watch... I'll be the only guy who doesn't benefit from this
> Pertronix upgrade... 'cept for taking points out of the system. Points
> and condensers are evil.
>
> Kelvin
> :
> > When I put the Pertronix in my coaches BF, I set it at 26* and the old
> beast loves it. It starts like a champ and runs so well I hate to shut it
> down sometimes. We have slept over it on more than a few occasions when we
> had a bad coach battery.
> >
> > Matt
>
> _______________________________________________
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> Unsubscribe or Change List Options:
> http://temp.gmcnet.org/cgi-bin/mailman/listinfo/gmclist
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| Re: [GMCnet] Onan Pertronix Upgrade... [message #116998 is a reply to message #116979] |
Mon, 28 February 2011 20:41 |
Ken Burton
Messages: 10030
Registered: January 2004
Location: Hebron, Indiana
Karma: 10
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Senior Member |
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Keep in mind that is a fixed timing value at ALL speeds. I am surprised that it even starts at the number. It sure seems to me that at that value it would be firing BEFORE the piston reaches TDC during the slow speed cranking when starting.
55 degrees is an awful lot of advance.
Are you sure you are not misreading that value on the flywheel or reading the wrong timing mark?
Ken Burton - N9KB
76 Palm Beach
Hebron, Indiana
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| Re: [GMCnet] Onan Pertronix Upgrade... [message #117001 is a reply to message #116961] |
Mon, 28 February 2011 20:59 |
Dennis S
Messages: 3046
Registered: November 2005
Karma: 2
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Senior Member |
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| Kelvin Dietz wrote on Mon, 28 February 2011 14:43 |
Couple of questions...
The 4Kw in my 230 has two timing marks on the back shroud. One is TDC
and one is 21° BTDC. When I install the Pertonix sensor I figured to
set the timing at 21° but the manuals I've seen say 20° or 25°.
Question: Would there be any point in changing the timing? To what?
I've seen reference to that but don't remember anyone posting timing
numbers. Advancing the timing as far as possible is a good thing in a
car. More advance be good for an Onan?
I've torn the Barbarian down quite a ways. Starter is off (bracket is
in good shape) and I removed the Oil Filter adaptor. Both bolts were
pretty loose. I think that's where my oil leak was coming from.
Question: I see "copper" washers under a number of bolts and nuts. No
lock washers. What's the deal with those? Are they some form of lock
washer? Are they there to avoid electrolysis between aluminum castings
and steel hardware?
I'm adding lock washers and Blue Loctite, just because...
TIA,
Kelvin
'73 23' in Eugene, OR
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Kelvin,
Saturday I started on the same project, using a Pertronix 1181. Not finished but put up a few photos and have some input.
The maintenance manual I have specs the 4kw with .025" point gap, 26 degree btc static timing and 21 degree dynamic (running) hot timing.
Here is where I picked for cold btc timing
http://www.gmcmhphotos.com/photos/showphoto.php?photo=37949&title=pertronix2-003&cat=5722
Other photos show how I filed the magnet location and such.
I presumed the yellow dot on the module to be accurate -- may be a bad assumption.
http://www.gmcmhphotos.com/photos/showphoto.php?photo=37952&title=pertronix-0021&cat=5722
No timing light available so I went with a static setting. It does not run as smoothly as the points set-up -- so I have to find a timing light -- then check and reset timing as necessary.
I used plastic from which to fabricate the mounting bracket. The module must be grounded to the engine so I had to add a grounding wire. Not sure if I like the bracket so may fabricate another using aluminum -- just not a lot or room on the back plate for convenient locating and installing.
As for oil leaks, it appears the oil dip stick can vibrate loose and pump a lot onto the top of the engine. Some of the factory installed gaskets were poorly aligned and I made new valve spring access port cover gaskets from 1/16 inch cork to improve sealing.
May not get back to finish mine for a week or two -- so please let me know how you proceed.
Dennis
Dennis S
73 Painted Desert 230
Memphis TN Metro
[Updated on: Mon, 28 February 2011 21:13] Report message to a moderator |
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| Re: [GMCnet] Onan Pertronix Upgrade... [message #117004 is a reply to message #116961] |
Mon, 28 February 2011 21:16 |
GMCNUSA
Messages: 283
Registered: August 2006
Location: Indianapolis, IN
Karma: 0
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Senior Member |
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| Kelvin Dietz wrote on Mon, 28 February 2011 15:43 |
Couple of questions...
The 4Kw in my 230 has two timing marks on the back shroud. One is TDC
and one is 21° BTDC. When I install the Pertonix sensor I figured to
set the timing at 21° but the manuals I've seen say 20° or 25°.
Question: Would there be any point in changing the timing? To what?
Kelvin
'73 23' in Eugene, OR
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My Onan never ran more than 20 to 45 minutes in the 4 years I used the coach. now after decarbonizing the heads and installing the Pertronix at 27 deg. advance. It runs very well never stops and runs 2 roof A/Cs and microwave or what ever all at the same time. I now have a good gen set.
Larry Dilk
Indianapolis, IN
76 Eleganza II
Patterson 455,Turbo City TBI,
Just LOVE It!
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| Re: [GMCnet] Onan Pertronix Upgrade... [message #117050 is a reply to message #117001] |
Tue, 01 March 2011 09:18 |
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mike miller
Messages: 3576
Registered: February 2004
Location: Hillsboro, Oregon
Karma: 0
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Senior Member |
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| Dennis S wrote on Mon, 28 February 2011 18:59 |
...
Other photos show how I filed the magnet location and such.
I presumed the yellow dot on the module to be accurate -- may be a bad assumption.
http://www.gmcmhphotos.com/photos/showphoto.php?photo=37952&title=pertronix-0021&cat=5722
No timing light available so I went with a static setting. It does not run as smoothly as the points set-up -- so I have to find a timing light -- then check and reset timing as necessary.
...
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I found the yellow dot to be more of a "ball-park" setting. I tried several different timings with the module bracket clamped with vise grips before drilling the mounting holes and fastening it down.
Mike Miller -- Hillsboro, OR -- on the Black list
(#2)`78 23' Birchaven Rear Bath -- (#3)`77 23' Birchaven Side Bath
More Sidekicks than GMC's and a late model Malibu called 'Boo'
http://m000035.blogspot.com
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| Re: [GMCnet] Onan Pertronix Upgrade... [message #117053 is a reply to message #117050] |
Tue, 01 March 2011 09:42 |
Dennis S
Messages: 3046
Registered: November 2005
Karma: 2
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Senior Member |
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| mike miller wrote on Tue, 01 March 2011 09:18 |
| Dennis S wrote on Mon, 28 February 2011 18:59 |
...
Other photos show how I filed the magnet location and such.
I presumed the yellow dot on the module to be accurate -- may be a bad assumption.
http://www.gmcmhphotos.com/photos/showphoto.php?photo=37952&title=pertronix-0021&cat=5722
No timing light available so I went with a static setting. It does not run as smoothly as the points set-up -- so I have to find a timing light -- then check and reset timing as necessary.
...
|
I found the yellow dot to be more of a "ball-park" setting. I tried several different timings with the module bracket clamped with vise grips before drilling the mounting holes and fastening it down.
|
Mike
From leading edge to trailing I estimate about 8, eight, degrees -- plenty of room for error.
What did you use for your final timing advance?
Denniis
Dennis S
73 Painted Desert 230
Memphis TN Metro
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| Re: [GMCnet] Onan Pertronix Upgrade... [message #117055 is a reply to message #117053] |
Tue, 01 March 2011 09:53 |
Dennis S
Messages: 3046
Registered: November 2005
Karma: 2
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Senior Member |
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Mike
Ignore my question on your advance timing -- I see you answered in a previous thread.
Thanks again,
Dennis
| Dennis S wrote on Tue, 01 March 2011 09:42 |
| mike miller wrote on Tue, 01 March 2011 09:18 |
| Dennis S wrote on Mon, 28 February 2011 18:59 |
...
Other photos show how I filed the magnet location and such.
I presumed the yellow dot on the module to be accurate -- may be a bad assumption.
http://www.gmcmhphotos.com/photos/showphoto.php?photo=37952&title=pertronix-0021&cat=5722
No timing light available so I went with a static setting. It does not run as smoothly as the points set-up -- so I have to find a timing light -- then check and reset timing as necessary.
...
|
I found the yellow dot to be more of a "ball-park" setting. I tried several different timings with the module bracket clamped with vise grips before drilling the mounting holes and fastening it down.
|
Mike
From leading edge to trailing I estimate about 8, eight, degrees -- plenty of room for error.
What did you use for your final timing advance?
Denniis
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Dennis S
73 Painted Desert 230
Memphis TN Metro
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| Re: [GMCnet] Onan Pertronix Upgrade... [message #117070 is a reply to message #117064] |
Tue, 01 March 2011 10:45 |
Dennis S
Messages: 3046
Registered: November 2005
Karma: 2
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Kelvin
The covers are under the intake manifold -- access to setting the valve lash.
Locating the module higher let me bring the wires out above the side covers -- and I didn't have to bend over as far!
Dennis
Dennis Sexton
73 GMC
TN
Sent from my iPad
On Mar 1, 2011, at 10:23 AM, KRDietz <krdietz@gmail.com> wrote:
>
>> I used plastic from which to fabricate the mounting bracket. The module must be grounded to the engine so I had to add a grounding wire. Not sure if I like the bracket so may fabricate another using aluminum -- just not a lot or room on the back plate for convenient locating and installing.
>
> Why not locate the module where Mike MIller did?
> http://www.gmcmhphotos.com/photos/showphoto.php?photo=37855
>
> No reason it has to be at the top of the flywheel. Lots more room down
> low. Do drill just one hole, however. Mike was a little less than
> attentive the first time. :^)
>> As for oil leaks, it appears the oil dip stick can vibrate loose and pump a lot onto the top of the engine.
>
> Wasn't much problem up there. The dipstick still fits the tube pretty
> well.
>
>> Some of the factory installed gaskets were poorly aligned and I made new valve spring acces port cover gaskets from 1/16 inch cork to improve sealing.
>
> Not sure where those are. Now I've gotta go take a look and see if I
> need to whip up some gaskets. ;^)
>
> Thanks,
> Kelvin
>
> _______________________________________________
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Dennis S
73 Painted Desert 230
Memphis TN Metro
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| Re: [GMCnet] Onan Pertronix Upgrade... [message #117077 is a reply to message #117070] |
Tue, 01 March 2011 11:39 |
pickle4k
Messages: 129
Registered: January 2011
Location: San Leandro
Karma: 0
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I have to ask........
My PO installed a 2.8K Onan in my coach. Does anyone have experiance with this small unit? Mine is runnng rough and it takes a long time to get running smooth and up to developing 120V. It sounds that the Pertronics upgrade is the way to go and I would love to get it done. This unit only has enough power my roof A/C unit, nothing else can be used at the same time. The cash for the upgrade to a new 4k Onan is not in the bank at this time.
Thanks for you input, you guys are the most informative bunch.
Nick R. NorCal
76-23'Transmode-Norris
Rear Bath and
75-26' Avion
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| Re: [GMCnet] Onan Pertronix Upgrade... [message #117088 is a reply to message #116975] |
Tue, 01 March 2011 12:50 |
Dennis S
Messages: 3046
Registered: November 2005
Karma: 2
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Senior Member |
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| mcolie wrote on Mon, 28 February 2011 16:54 |
I hit send too soon.
When I put the Pertronix in my coaches BF, I set it at 26* and the old beast loves it. It starts like a champ and runs so well I hate to shut it down sometimes. We have slept over it on more than a few occasions when we had a bad coach battery.
Matt
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Matt,
If your 73 is stock -- did you do anything to seal the generator compartment?
Mine has a plywood cut-out to allow battery access from inside, but no seal.
Dennis
Dennis S
73 Painted Desert 230
Memphis TN Metro
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| Re: [GMCnet] Onan Pertronix Upgrade... [message #117114 is a reply to message #117077] |
Tue, 01 March 2011 16:49 |
bhayes
Messages: 263
Registered: March 2010
Karma: 1
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Senior Member |
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Nick, is it the Microlite 2800? I had about 1000 hours on an Onan 2800 Microlite when it started having issues such as stalling, running rough, and finally not even starting. I replaced the carburetor, and that seemed to do the trick. (I also replaced the low oil sensor and brushes, but I don't think those items were related to the problems.)
Bryan Hayes
'76 Eleganza II
Salt Lake City, Utah
Bryan Hayes
'76 Eleganza II
Salt Lake City, Utah
[Updated on: Tue, 01 March 2011 16:50] Report message to a moderator |
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