| Distributor o-ring [message #314003] |
Fri, 03 March 2017 07:04  |
Tilerpep
Messages: 404
Registered: June 2013
Location: Raleigh, NC
Karma: 7
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Senior Member |
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I pulled the distributor on the 78 Royale, and it did not have an oring where it sits in the engine. The way I read the parts book, p.7-16 and 7-18, the old style had an o-ring and the HEI did not. The one I pulled out was VERY stuck/gunked in (I used a steady pull from above with a ratchet strap on the gantry I built to pull the intake manifold, and then tapped with a rubber mallet for nearly half hour. lots of PB blaster). Should I grease and re-install with no o-ring?
1975 Glenbrook, 1978 Royale rear bath
Raleigh, NC
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| Re: Distributor o-ring [message #314009 is a reply to message #314003] |
Fri, 03 March 2017 08:37  |
Bullitthead
Messages: 1411
Registered: November 2013
Karma: 5
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If there is a groove for an oring in the distributor and a corresponding sealing surface in the block, I would put an oring in there. Otherwise use the flat gasket and get the timing right before it gets soaked with oil so it won't leak later. Or use both if you have a problem leak.
Terry Kelpien
ASE Master Technician
73 Glacier 260
Smithfield, Va.
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| Re: [GMCnet] Distributor O-ring [message #314023 is a reply to message #314003] |
Fri, 03 March 2017 13:06 |
Kosier
Messages: 834
Registered: February 2008
Karma: 1
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Tyler,
All the real Olds distributors had an O-ring originally. I got new ones
from GM a couple of years ago. I would recommend some sort
of antiseize on the aluminum housing where it contacts the iron block. A
little corrosion really sticks those things fast.
Gary Kosier
77PB w/500Cad
Newark, Ohio
--------------------------------------------------
From: "Tyler"
Sent: Friday, March 03, 2017 8:04 AM
To:
Subject: [GMCnet] Distributor o-ring
> I pulled the distributor on the 78 Royale, and it did not have an oring
> where it sits in the engine. The way I read the parts book, p.7-16 and
> 7-18,
> the old style had an o-ring and the HEI did not. The one I pulled out was
> VERY stuck/gunked in (I used a steady pull from above with a ratchet strap
> on the gantry I built to pull the intake manifold, and then tapped with a
> rubber mallet for nearly half hour. lots of PB blaster). Should I grease
> and
> re-install with no o-ring?
> --
> 1975 Glenbrook, 1978 Royale rear bath
> Raleigh, NC
>
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:
> http://list.gmcnet.org/mailman/listinfo/gmclist_list.gmcnet.org
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| Re: Distributor o-ring [message #314034 is a reply to message #314003] |
Sat, 04 March 2017 02:08 |
Ken Burton
Messages: 10030
Registered: January 2004
Location: Hebron, Indiana
Karma: 10
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Your distributor sticking in place is a common occurrence. The problem in not caused by the absence of a gasket or an O-ring. What you are experiencing is bi-metal corrosion. (Aluminum distributor inserted into a steel hole.) If you wish, you can get a flat gasket or an O-ring, but that will not prevent it from happening again. To prevent it I suggest that you lubricate the contact area on the distributor and the intake manifold with anti-seize prior to reassembling it.
It should be noted that the ground connection for both the 12 volt supply to the distributor and the high voltage return from the spark plugs flows through this connection. When bi-metal corrosion in that joint occurs, sometimes you will loose the ground path to the distributor components.
So as previously mentioned in another post, an added 18 to 14 gauge wire from the base of the distributor to any bolt on the engine block is highly recommended. If you have a Dick Paterson rebuilt distributor you will find an unused stud and nut on the bottom of the distributor for this purpose.
Ken Burton - N9KB
76 Palm Beach
Hebron, Indiana
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| Re: [GMCnet] Distributor o-ring [message #314063 is a reply to message #314059] |
Sat, 04 March 2017 17:45 |
Ken Henderson
Messages: 8726
Registered: March 2004
Location: Americus, GA
Karma: 9
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Larry,
Ken H. agrees with Ken B.: The high voltage secondary needs a ground path
just as badly as the primary -- the distributor body serves for both.
Ken H.
On Sat, Mar 4, 2017 at 6:02 PM, Larry wrote:
> Ken Burton wrote on Sat, 04 March 2017 02:08
>> It should be noted that the ground connection for both the 12 volt
> supply to the distributor and the high voltage return from the spark plugs
>> flows through this connection. When bi-metal corrosion in that joint
> occurs, sometimes you will loose the ground path to the distributor
>> components.
>
> Ken,
> (and the high voltage return from the spark plugs flows through this
> connection.) Are you sure about this? IIRC, High voltage is on the
> secondary
> side of the coil and not directly connected to the primary side....or have
> I got this wrong?
>
> --
>
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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] Distributor o-ring [message #314068 is a reply to message #314063] |
Sat, 04 March 2017 18:18 |
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USAussie
Messages: 15912
Registered: July 2007
Location: Sydney, Australia
Karma: 6
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G'day,
Keeping in mind that I am electrically challenged I thought the high voltage
traveled through the spark plug wires to the center of the sparkplug -
across the gap - to the plug body - to the engine block which is the ground.
Regards,
Rob M.
The Pedantic Mechanic
USAussie - Downunder
AUS '75 Avion - The Blue Streak TZE365V100428
USA '75 Avion - Double Trouble TZE365V100426
USA '77 Kingsley - TZE 267V100808
-----Original Message-----
From: Gmclist [mailto:gmclist-bounces@list.gmcnet.org] On Behalf Of Ken
Henderson
Sent: Sunday, March 5, 2017 10:45 AM
To: gmclist@list.gmcnet.org
Subject: Re: [GMCnet] Distributor o-ring
Larry,
Ken H. agrees with Ken B.: The high voltage secondary needs a ground path
just as badly as the primary -- the distributor body serves for both.
Ken H.
On Sat, Mar 4, 2017 at 6:02 PM, Larry wrote:
> Ken Burton wrote on Sat, 04 March 2017 02:08
>> It should be noted that the ground connection for both the 12 volt
> supply to the distributor and the high voltage return from the spark plugs
>> flows through this connection. When bi-metal corrosion in that joint
> occurs, sometimes you will loose the ground path to the distributor
>> components.
>
> Ken,
> (and the high voltage return from the spark plugs flows through this
> connection.) Are you sure about this? IIRC, High voltage is on the
> secondary
> side of the coil and not directly connected to the primary side....or have
> I got this wrong?
>
> --
>
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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] Distributor o-ring [message #314085 is a reply to message #314063] |
Sat, 04 March 2017 21:47 |
Larry
Messages: 2875
Registered: January 2004
Location: Menomonie, WI
Karma: 10
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Ken Henderson wrote on Sat, 04 March 2017 17:45Larry,
Ken H. agrees with Ken B.: The high voltage secondary needs a ground path
just as badly as the primary -- the distributor body serves for both.
Ken H.
Ken,
IIRC, the primary needs ground for the current to flow from ignition switch through the primary windings...then to ground. The secondary is isolated from the primary by the coating on the many windings. When the primary circuit flow is interupted by points or other electronic means, the magnetic field collapses, induces high voltage in the secondary and flow is through the coil wire to center of distributor, through the rotor, to contacts in the distributor, through the plug wire, to the spark plug center electrode.......and THEN to ground at the spark plug. The distributor housing is not the ground for the secondary. Take a Ohm meter and measure continuity from the secondary lead to the coil case or ground....nothing. Have I had it wrong all of these years?
Larry 
78 Royale w/500 Caddy
Menomonie, WI.
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| Re: Distributor o-ring [message #314086 is a reply to message #314003] |
Sat, 04 March 2017 21:50 |
JohnL455
Messages: 4447
Registered: October 2006
Location: Woodstock, IL
Karma: 12
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Senior Member |
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Both the primary and secondary windings have 2 wires. Primary has 12v and switched ground via points or module. Secondary has one side to ground and other out to rotor and to ground through plug gap to complete circuit. Next weeks lesson can be waste spark systems like on the Onan.
John Lebetski
Woodstock, IL
77 Eleganza II
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| Re: Distributor o-ring [message #314088 is a reply to message #314059] |
Sat, 04 March 2017 23:00 |
Ken Burton
Messages: 10030
Registered: January 2004
Location: Hebron, Indiana
Karma: 10
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Larry wrote on Sat, 04 March 2017 17:02Ken Burton wrote on Sat, 04 March 2017 02:08
It should be noted that the ground connection for both the 12 volt supply to the distributor and the high voltage return from the spark plugs flows through this connection. When bi-metal corrosion in that joint occurs, sometimes you will loose the ground path to the distributor components.
Ken,
(and the high voltage return from the spark plugs flows through this connection.) Are you sure about this? IIRC, High voltage is on the secondary side of the coil and not directly connected to the primary side....or have I got this wrong?
Yes I am. When you fire a spark plug, high voltage and very low current goes through the plug to ground (the engine). The only return path to the coil for this high voltage and low current is via the engine and the distributor frame on an HEI ignition.
The next time you have an HEI distributor cap off, remove top cover and notice the single (I believe it is black) wire under one of the mounting bolts for the coil. That is the ground return for the secondary (High voltage) side of the coil. Follow that black wire and see where it goes.
You are correct in your statement that the primary and secondary sides are not directly connected to each other on an HEI system. They do eventually share a common ground. In a points system the coil primary side ground is interrupted by the points opening and closing. In an HEI system the ignition module does the same interruption on the primary side. On the secondary side the return to the coil always grounded.
On a points ignition the coil is mounted on the engine so the return is not normally through the distributor frame on most vehicles. Read the below because this may not be true on a GMC.
I remember very little specifics on GM 12 volt points ignition systems but there is an interesting anomaly on the 73 GMC points wiring diagram. I really believe it is incorrect. The diagram shows the primary and secondary ground side of the coil wired together. So the secondary ground return would then be through the points. I do not have a coil here to measure, but if this is really true then the secondary of the coil would also get it's ground through the points and the distributor frame. I have never seen this before but I guess it could work.
That is probably more information than you wanted to know. Just keep a good ground connection between the base of the distributor and the master ground (the engine) and everything will work correctly.
Ken Burton - N9KB
76 Palm Beach
Hebron, Indiana
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| Re: Distributor o-ring [message #314089 is a reply to message #314088] |
Sat, 04 March 2017 23:27 |
Bullitthead
Messages: 1411
Registered: November 2013
Karma: 5
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Senior Member |
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"The diagram shows the primary and secondary ground side of the coil wired together. So the secondary ground return would then be through the points"
Electrically they are the same.
That is one of the purposes of the condenser. The other is to absorb the backflow from the primary windings. The third is to reduce/absorb "switch bounce".
Terry Kelpien
ASE Master Technician
73 Glacier 260
Smithfield, Va.
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| Re: [GMCnet] Distributor o-ring [message #314090 is a reply to message #314085] |
Sat, 04 March 2017 23:36 |
Bullitthead
Messages: 1411
Registered: November 2013
Karma: 5
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Senior Member |
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"Take a Ohm meter and measure continuity from the secondary lead to the coil case or ground....nothing. Have I had it wrong all of these years?"
Crank up the voltage on that voltmeter (maybe have to use a megger) and you'll be able to see that resistance of the windings to the ground. The other end of that spark plug wire circuit has to start somewhere, right? Otherwise there would be lightning INSIDE the coil (and then you will be on the side of the road).
Can't wait for John's waste spark class!
Terry Kelpien
ASE Master Technician
73 Glacier 260
Smithfield, Va.
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| Re: Distributor o-ring [message #314094 is a reply to message #314089] |
Sun, 05 March 2017 00:31 |
Ken Burton
Messages: 10030
Registered: January 2004
Location: Hebron, Indiana
Karma: 10
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Senior Member |
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Bullitthead wrote on Sat, 04 March 2017 23:27"The diagram shows the primary and secondary ground side of the coil wired together. So the secondary ground return would then be through the points"
Electrically they are the same.
That is one of the purposes of the condenser. The other is to absorb the backflow from the primary windings. The third is to reduce/absorb "switch bounce".
That is not the point. Normally the coil is mounted with the secondary connected direct to ground. In the case of this diagram the secondary is shown as switched to ground through the points. Also the secondary fires when the points are opened (not closed) so no return path would be available until the points closed again. I am really questioning whether this will really work as diagrammed. I have never seen one wired this way on any points type ignition. I really need to meter a GMC coil to see if this diagram is really true. At this point I do not think it is.
Note: The condenser / capacitor is there to reduce the kick back and reducing arcing across the points when the points are opened.
Ken Burton - N9KB
76 Palm Beach
Hebron, Indiana
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| Re: Distributor o-ring [message #314101 is a reply to message #314003] |
Sun, 05 March 2017 08:33 |
jhbridges
Messages: 8412
Registered: May 2011
Location: Braselton ga
Karma: -74
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The condenser also makes a tuned circuit with the coil to maximize the spark. The system won't work without it.
--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: Distributor o-ring [message #314103 is a reply to message #314003] |
Sun, 05 March 2017 10:02 |
JohnL455
Messages: 4447
Registered: October 2006
Location: Woodstock, IL
Karma: 12
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Ken B I don't have that diagram to view but I bet it is just poorly drawn. One line connected with a dot or not could be easilly omitted or miss drawn. It's s very simple concept either of us could draw on a bar napkin in 30 seconds. Over the years I have found many errors in GM factory service manuals not surprizing give the task of so many vehicle platforms and RPO variables not to mention mid year changes.
John Lebetski
Woodstock, IL
77 Eleganza II
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| Re: Distributor o-ring [message #314125 is a reply to message #314103] |
Sun, 05 March 2017 20:43 |
Ken Burton
Messages: 10030
Registered: January 2004
Location: Hebron, Indiana
Karma: 10
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Thanks John. That is what I'm thinking too. Especially since the diagrams is for the first year that the GMC was sold.
I saw it on the 1973 GMC wiring diagram so I mentioned it in case I was incorrect in my understanding on how it normally works on a GMC.
It is not that important because it has worked correctly for many, many years on many, many vehicles.
Someday I will run into someone with a spare coil and I'll satisfy my curiosity with an ohm meter.
This is an interesting academic exercise.
Ken Burton - N9KB
76 Palm Beach
Hebron, Indiana
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