Home » Public Forums » GMCnet » [GMCnet] 2nd last cylinder doesn't receive spark
| [GMCnet] 2nd last cylinder doesn't receive spark [message #324898] |
Fri, 13 October 2017 09:12  |
Olly Schmidt
Messages: 1265
Registered: February 2014
Location: Germany and Scottsville, ...
Karma: 8
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My '73 isn't running happily.
Replaced spark plugs, didn't change things.
Replaced distributor cap, didn't change things.
Went ahead, and took each of the plug wires, plug an external spark plug
into it. 6 of 8 cylinders produce a spark. The 2nd last on both sides do
not, i.e. 5 and 6 if you count from the left top.
Changed distributor caps. Issue remains in 5 (and 6).
Switched cables between 5 and 7, the issue remains in 5.
I am out of ideas, and appreciate feedback from the combined GMCnet
wisdom :-)
Thanks
--
Best regards
Peer Oliver Schmidt
PGP Key ID: 0x83E1C2EA
'76a Eleganza II 26', VA
'73 Sequoia 23', Germany, SH
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Best regards
Olly Schmidt
PGP Key ID: 0x18a9 3a1f 4196 bf22
'76a Eleganza II, VA
'73 Sequoia, SH, Germany
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| Re: [GMCnet] 2nd last cylinder doesn't receive spark [message #324904 is a reply to message #324898] |
Fri, 13 October 2017 10:26  |
James Hupy
Messages: 6806
Registered: May 2010
Karma: -62
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Most of the time, those wires are NOT wire, but nylon strands that have
been turned into carbon traces by running huge current through them. They
are extremely delicate, particularly if one pulls on them. The only thing
that they are GOOD at, is TVRS suppression. (Electronic static and radio
noise ). I remember the days of Packard 440 ignition wires. Spark got where
it was supposed to get, every time. But drive it down the street and every
analog receiver nearby had some interference from it. Anyway, I have had
enough new suppression wires not work out of the box to make me suspicious
of any new set. I think they are supposed to have 5k ohms per foot of cable
length when new. Check them with a good ohm meter. Similar length wires
should have nearly the same resistance. Jwik.
Jim Hupy
Salem, Or
78 GMC ROYALE 403
On Oct 13, 2017 8:04 AM, "Terry" wrote:
Check those wires since messing with them changed the scenario...substitute
some others that are known good instead of playing musical wires as that
can lead you astray :)
--
Terry Kelpien
ASE Master Technician
73 Glacier 260
Smithfield, Va.
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| Re: [GMCnet] 2nd last cylinder doesn't receive spark [message #324906 is a reply to message #324898] |
Fri, 13 October 2017 12:15 |
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Matt Colie
Messages: 8547
Registered: March 2007
Location: S.E. Michigan
Karma: 7
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Peer Oliver Schmidt wrote on Fri, 13 October 2017 10:12My '73 isn't running happily.
Replaced spark plugs, didn't change things.
Replaced distributor cap, didn't change things.
Went ahead, and took each of the plug wires, plug an external spark plug into it. 6 of 8 cylinders produce a spark. The 2nd last on both sides do not, i.e. 5 and 6 if you count from the left top.
Changed distributor caps. Issue remains in 5 (and 6).
Switched cables between 5 and 7, the issue remains in 5.
I am out of ideas, and appreciate feedback from the combined GMCnet wisdom 
Thanks
--
Best regards
Peer Oliver Schmidt
Peer,
Ready for a Way Out test??
When you have the cap off you can see the ring that was added with the install of the Pertronix 1181. Take a small steel something, (I used a small screwdriver) and run it around the under surface of that ring. It should try to stick to 8 places on the way around. If it does not, there is your problem.
While I have never had a Pertronix module fail, I did discover a missing magnet in a ring/rotor just once.
We started that diagnostic by pulling the wire out of the cap and cranking and one in the party noticed a missing spark. (Unfortunately, I can't claim that one.) I was looking and thought it looked good. The above test found the issue.
Other than that, I would be testing wires. That takes a VOM that can read megohms.
Please let us know when you find it.
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] 2nd last cylinder doesn't receive spark [message #324908 is a reply to message #324906] |
Fri, 13 October 2017 12:34 |
jimk
Messages: 6734
Registered: July 2006
Location: Belmont, CA
Karma: 9
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Senior Member |
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Pertronix now have the one s that sense the lobe off the shaft, not as
efficient in timing as the 8 magnets, but we do not run into those problems.
On Fri, Oct 13, 2017 at 10:15 AM, Matt Colie wrote:
> Peer Oliver Schmidt wrote on Fri, 13 October 2017 10:12
>> My '73 isn't running happily.
>>
>> Replaced spark plugs, didn't change things.
>> Replaced distributor cap, didn't change things.
>>
>> Went ahead, and took each of the plug wires, plug an external spark plug
> into it. 6 of 8 cylinders produce a spark. The 2nd last on both sides do
>> not, i.e. 5 and 6 if you count from the left top.
>>
>> Changed distributor caps. Issue remains in 5 (and 6).
>>
>> Switched cables between 5 and 7, the issue remains in 5.
>>
>> I am out of ideas, and appreciate feedback from the combined GMCnet
> wisdom :)
>>
>> Thanks
>> --
>> Best regards
>>
>> Peer Oliver Schmidt
>
> Peer,
>
> Ready for a Way Out test??
> When you have the cap off you can see the ring that was added with the
> install of the Pertronix 1181. Take a small steel something, (I used a
> small
> screwdriver) and run it around the under surface of that ring. It should
> try to stick to 8 places on the way around. If it does not, there is your
> problem.
>
> While I have never had a Pertronix module fail, I did discover a missing
> magnet in a ring/rotor just once.
>
> We started that diagnostic by pulling the wire out of the cap and cranking
> and one in the party noticed a missing spark. (Unfortunately, I can't
> claim that one.) I was looking and thought it looked good. The above test
> found the issue.
>
> Other than that, I would be testing wires. That takes a VOM that can read
> megohms.
>
> Please let us know when you find it.
>
> Matt
> --
> Matt & Mary Colie - '73 Glacier 23 - Members GMCMI, GMCGL, GMCES
> Electronically Controlled Quiet Engine Cooling Fan
> OE Rear Drum Brakes with Applied Control Arms
> SE Michigan - Twixt A2 and Detroit
>
> _______________________________________________
> 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] 2nd last cylinder doesn't receive spark [message #324915 is a reply to message #324898] |
Fri, 13 October 2017 17:00 |
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USAussie
Messages: 15912
Registered: July 2007
Location: Sydney, Australia
Karma: 6
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Senior Member |
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Peer,
If I were you I'd order a set of plug wires from:
Dick Paterson's Springfield Performance Ignition: Recurved Distributors, Spark Plug Wire Sets, Rebuilt Carburetors, Engines,
Transmissions
http://www.springfield-ignition.com/
Regards,
Rob M.
The Pedantic Mechanic
Sydney, Australia
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 Peer Oliver Schmidt GMC
Sent: Friday, October 13, 2017 10:13 PM
To: gmclist@list.gmcnet.org
Subject: [GMCnet] 2nd last cylinder doesn't receive spark
My '73 isn't running happily.
Replaced spark plugs, didn't change things.
Replaced distributor cap, didn't change things.
Went ahead, and took each of the plug wires, plug an external spark plug
into it. 6 of 8 cylinders produce a spark. The 2nd last on both sides do
not, i.e. 5 and 6 if you count from the left top.
Changed distributor caps. Issue remains in 5 (and 6).
Switched cables between 5 and 7, the issue remains in 5.
I am out of ideas, and appreciate feedback from the combined GMCnet
wisdom :-)
Thanks
--
Best regards
Peer Oliver Schmidt
_______________________________________________
GMCnet mailing list
Unsubscribe or Change List Options:
http://list.gmcnet.org/mailman/listinfo/gmclist_list.gmcnet.org
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] 2nd last cylinder doesn't receive spark [message #324922 is a reply to message #324898] |
Fri, 13 October 2017 18:22 |
jhbridges
Messages: 8412
Registered: May 2011
Location: Braselton ga
Karma: -74
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Senior Member |
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I rescind my comments - I'm totally unfamiliar with the Pertronix product.
Although my current coah has one on it - "Flamethrower"
--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] 2nd last cylinder doesn't receive spark [message #324933 is a reply to message #324898] |
Sat, 14 October 2017 08:21 |
jhbridges
Messages: 8412
Registered: May 2011
Location: Braselton ga
Karma: -74
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Senior Member |
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Uh Opps. MSD Flamethrower. I'm not familiar with Pertronix atall.
--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] 2nd last cylinder doesn't receive spark [message #324940 is a reply to message #324898] |
Sat, 14 October 2017 11:57 |
roy1
Messages: 2126
Registered: July 2004
Location: Minden nevada
Karma: 6
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Senior Member |
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Appears you narrowed it down to a problem with the distributor itself. I would replace the distributor. My personal choice is an HEI as parts are available every ware but that is your decision.
Roy Keen
Minden,NV
76 X Glenbrook
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| Re: [GMCnet] 2nd last cylinder doesn't receive spark [message #324961 is a reply to message #324898] |
Sun, 15 October 2017 09:03 |
JohnL455
Messages: 4447
Registered: October 2006
Location: Woodstock, IL
Karma: 12
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Senior Member |
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Glad you found it. This happened to my friend on his Buick GS Pertronix conversion. I installed a newer type with the cam lobe reader. Hope you changed the oil and filter to get rid of all the fuel wash.
John Lebetski
Woodstock, IL
77 Eleganza II
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| Re: [GMCnet] 2nd last cylinder doesn't receive spark - Solved [message #324968 is a reply to message #324964] |
Sun, 15 October 2017 12:44 |
Olly Schmidt
Messages: 1265
Registered: February 2014
Location: Germany and Scottsville, ...
Karma: 8
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Senior Member |
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John Lebetski schrieb/wrote
> Hope you changed the oil and filter to get rid of all the fuel wash.
I changed the oil, but was told that the filter isn't that important, so
I didn't. Which was a good thing, cause I only had 5 litres of oil
Jim Miller schrieb/wrote
> Did you find them inside the housing? IIRC they are captive in the > plastic ring underneath clear tape, did this tape fail in some way?
http://possy.de/magnet.jpg show the culprits neatly placed next to each
other at the same place.
--
Best regards
Peer Oliver Schmidt
the internet company
PGP Key ID: 0x83E1C2EA
--
Best regards
Peer Oliver Schmidt
PGP Key ID: 0x83E1C2EA
'76a Eleganza II 26', VA
'73 Sequoia 23', Germany, SH
_______________________________________________
GMCnet mailing list
Unsubscribe or Change List Options:
http://list.gmcnet.org/mailman/listinfo/gmclist_list.gmcnet.org
Best regards
Olly Schmidt
PGP Key ID: 0x18a9 3a1f 4196 bf22
'76a Eleganza II, VA
'73 Sequoia, SH, Germany
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