EMP

[Greg C.]

I'm reading a really good book called "One Second After" which deals with the aftermath of an Electro Magnetic Pulse caused by the detonation of a
nuclear weapon at high altitude.

This got me to wondering, and I know there are some highly intelligent people on this forum, many with real world experience in addition to "book
larnin'". So I thought I would ask here.

I know that points and condenser ignition system automobiles would still operate after experiencing an EMP, although their 8-track stereos may not.

Since many of our coaches have the HEI ignition system, which seems to be a bridge between fully electronic and points systems,
would the HEI equipped vehicles survive an EMP and still function?

This is a purely hypothetical question for mental entertainment purposes and has nothing to do with a certain world power's drive for superiority and
domination. (grin).
--
Greg Crawford
KM4ZCR
Knoxville, TN

"Ruby Sue"
1977 Royale
Rear Bath
403 Engine
American Eagle Wheels
Early Version Alex Sirum Quad bags

 

[Jim Hupy]

One word. Shielding. Some electronic stuff is better shielded than others.
I speculate that lots of vulnerable stuff will go toes up, and better
protected stuff will survive it. Points and condenser will most likely
survive as will magneto ignitions. Their alternator regulators? Who knows.
Interesting to ponder, for sure.
Jim Hupy
Salem, Oregon

On Sat, Nov 6, 2021, 5:20 PM Greg Crawford
wrote:

> I'm reading a really good book called "One Second After" which deals with
> the aftermath of an Electro Magnetic Pulse caused by the detonation of a
> nuclear weapon at high altitude.
>
> This got me to wondering, and I know there are some highly intelligent
> people on this forum, many with real world experience in addition to "book
> larnin'". So I thought I would ask here.
>
> I know that points and condenser ignition system automobiles would still
> operate after experiencing an EMP, although their 8-track stereos may not.
>
> Since many of our coaches have the HEI ignition system, which seems to be
> a bridge between fully electronic and points systems,
> would the HEI equipped vehicles survive an EMP and still function?
>
> This is a purely hypothetical question for mental entertainment purposes
> and has nothing to do with a certain world power's drive for superiority and
> domination. (grin).
> --
> Greg Crawford
> KM4ZCR
> Knoxville, TN
>
> "Ruby Sue"
> 1977 Royale
> Rear Bath
> 403 Engine
> American Eagle Wheels
> Early Version Alex Sirum Quad bags
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:
>

 

[Matt Colie]

> I'm reading a really good book called "One Second After" which deals with the aftermath of an Electro Magnetic Pulse caused by the detonation of a
> nuclear weapon at high altitude.
> This got me to wondering, and I know there are some highly intelligent people on this forum, many with real world experience in addition to "book
> larnin'". So I thought I would ask here.
> I know that points and condenser ignition system automobiles would still operate after experiencing an EMP, although their 8-track stereos may
> not.
> Since many of our coaches have the HEI ignition system, which seems to be a bridge between fully electronic and points systems,
> would the HEI equipped vehicles survive an EMP and still function?
> This is a purely hypothetical question for mental entertainment purposes and has nothing to do with a certain world power's drive for superiority
> and domination. (grin).

Greg,

This is an interesting subject that was brought up when I was in a military-like trade school and headed for a Navy commission. This was about the
time that it was discovered that a lot of the Russian military's electronics was still using vacuum tubes (fire bottles). Intelligence people at
first thought that this was because they did not have the semi-conductor technology that we did. Then someone figured out that the old technology was
not easily killed with and EMP. This started a scramble in the military electronics groups. At first they thought that just being simple was enough
and then a massive solar flare took out a lot of Canada's power grid by killing insulators, transformers and circuit breakers. That started the
thinking all over again and new round of required testing for military suppliers (like my father's company).

Yes, shielding can do part of it, but anything sensitive that is connected to things outside the shielding is as risk. This is what could kill an
alternator. Many automotive systems in conventional passcars might survive because the body might be enough shield. Ego, your daily driver might
survive, but the coach not very likely. Remember the Corvettes that had all that sheet metal all over the ignition? That was so the car's radio
would work at all back when ignition wires were solid. Were it not for newer technology there, our radios would also be a lost cause...

As I recall from the reports at the time, Kettering (coil and points) ignition would likely survive as would most conventional magnetos. This sparked
(no pun intended) a massive move by the military to diesel only to then be cut down by the manufacture's change to electronic controls to meet new
standards. So look now and you will see an armored control system on all their engines.

Is this why I carry a set of points and condenser from my OE distributor in a jar in the engine spares? No, not really, that is because while very
trusting of the Pertonix parts that replaced them, I am somewhat (OK - seriously) paranoid about anything that as a single point failure can stop us
cold.

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

 

[Greg C.]

Matt and Jim, thank you for the thoughtful answers. I have considered swapping my HEI distributor on the coach for a points version, and then using
the Pertronix unit with points back up. I did this for several years in my 1966 Mustang. But the Pertronix never failed, probably because I was
carrying points and condenser in the trunk.

So the consensus is that the coach doesn't have enough sheet metal for a Faraday cage, and there are enough semiconductors present that an EMP would
probably knock out the ignition system?
--
Greg Crawford
KM4ZCR
Knoxville, TN

"Ruby Sue"
1977 Royale
Rear Bath
403 Engine
American Eagle Wheels
Early Version Alex Sirum Quad bags

 

[john r. lebetski]

The module takes a huge EMF magnetic pulse as well as high Back Voltage every time the electronic switch opens and the coil magnetism collapses. The
coil is magnetically close by and the Voltage rise back to the module is proportional to the Voltage rise on the secondary. Why pulling plug wires is
a bad idea as a “test”. This normal abuse happens 4 times per crank rotation.

--
John Lebetski
Woodstock, IL
77 Eleganza II

 

[Ken B]

I had quite an experience trying to keep all of the noise generated by the electronic ignition and other outside sources out of my mobile ham radio
gear mounted in the same vehicle. It was quite a chore.

GM published a document on the topic and would bring some cars that they modified to the major hamfests each year. They demonstrated what changes
they did on their demonstration cars and handed out that document to anyone that was interested.

I would assume EMP blocking / filtering would be similar to keeping other outside stuff from entering the vehicle. It should be the same exercise.
It took me many months of trying stuff to finally filter or block everything from entering the vehicle.

A couple of observations:

1. Shielding of the device(s) you are trying to protect is the absolute first item on the list.

2. Do not assume that all sheet metal on your vehicle will provide adequate shielding. It will not unless you take some extra steps to bond that
piece of metal to something connected to the main ground.

3. The lower the frequency of the undesired interference the more likely it will get through. The thing that generated the most noise was the
ignition, followed by the automatic speed control of the heat/AC fan. You would think the alternator should do some, but I never had to chase that
one.

4. One of the strangest fixes was grounding the rear end of the exhaust pipe to the frame.

I do not know much about EMP but if I were to worry about it I would treat it much like low frequency RF. After all EMP would be DC wouldn't it ?
--
Ken Burton - N9KB
76 Palm Beach
Hebron, Indiana

 

[john r. lebetski]

Just for data the oldest GM I own with factory HEI is a 76 Pontiac. Second oldest is my 77 TZE. 45 years of ‘burn in testing’ with never a module
failure. I bet no 2021 models by any maker will top that. So I think you’re gonna be ok. Just don’t make the secondary path difficult (worn
plugs, wires, cap, rotor) or the coil will increase the voltage rise to find a new spark path to ground.
--
John Lebetski
Woodstock, IL
77 Eleganza II

 

[mark sawyer]

Here is a good article if you really want to geek out on EMP...

Written by an engineer at Sandia about whether high altitude nuclear tests performed in the south pacific in the early 60s caused issues with the
streetlights on Oahu....

http://ece-research.unm.edu/summa/notes/SDAN/0031.pdf

The article, while not "purely hypothetical" does seem to have been written for "mental entertainment purposes" by the author, similar to the question
you pose....
--
Mark S. '73 Painted Desert,
Manny 1 Ton Front End,
Howell Injection,
Leigh Harrison 4bag and Rear Brakes,
Fort Worth, TX