Home Made Solid Copper Core RFI Sheilded Suppresiion Sparkplug wires.

[ozarquebus]

What do you think would be the result and/or net benefit of using solid 10 gauge copper wire with a tubular braided tinned copper shield as RFI suppression for spark plug wires?

[Two Checks]

I wouldn't. Not very vibration resistant.

[John Croucher]

Why re invent sparkplug wires?  If you can build them better than what is being manufactured and distributed in the market place, go for it. 

But sometimes, it is fun to sit at the work bench and roll your own parts and pieces just to say you can.  I get that part also. I do it all the time. 

[ozarquebus]

 I have all the materials laying around so cost would be zero. A braided shield should be effective RF suppression especially if grounded, Solid copper would be very excellent conductor as long as a resistive component is not needed on points/carbureted engine.

 Where would the vibration induced failure occur? At the connection of the cap to wire connection?

 Of course without suppression it would be like a safety device to cause cage drivers listening to their radio to take notice if you were in their proximity, but non-supression goes against my HAM radio credo.

I recall Model T and old tractors wires were just copper strips without insulation and a Guzzi is just like a Model T or a Johnny Popper, right?

[Two Checks]

You wouldn't have a cap to wire connection. The cap has a point that pierces the wire braid. Then the collar screws onto the cap itself making a compression type connection. Same thing at the coil.


Solid wire doesn't like vibration. Notice buildings use solid core and get anchored to the box. Appliances use braided wire as its flexible.

[garbln]

The real problem is getting solid 10Gage wire with high voltage insulation to put the shielding over.  That and the fact that the solid copper will work harden with vibration and fail with time.   Those old engines usually used some short springy brass strips and the distributor was firmly attached to the engine so there was very little relative motion between the mounting points so very little flexing or vibration.  On a mc the coils are usually mounted on the frame with longer wires to the plugs, so more vibes.

[nc43bsa]

Spark plug wires don't carry a lot of current, so the 10ga wire is gross overkill.  Even high performance "solid-core" wires are stranded, not solid; they are called that to differentiate them from graphite core wire sets.

And as has already been mentioned, the wires need to be more flexible than 10ga solid or they will break.

[Kiwi_Roy]

I have all the materials laying around so cost would be zero. A braided shield should be effective RF suppression especially if grounded, Solid copper would be very excellent conductor as long as a resistive component is not needed on points/carbureted engine.

 Where would the vibration induced failure occur? At the connection of the cap to wire connection?

 Of course without suppression it would be like a safety device to cause cage drivers listening to their radio to take notice if you were in their proximity, but non-supression goes against my HAM radio credo.

I recall Model T and old tractors wires were just copper strips without insulation and a Guzzi is just like a Model T or a Johnny Popper, right?

I can't recall seeing any spark leads with a braided shield, it's not necessary but it should work.
I do remember back in the 60s (NZ) when it became mandatory to add resistors, every house had a TV aerial on the roof and passing cars would throw a sparkly line across the B&W TV.
I wonder if a modern coil would get overloaded without the suppressor resistor, you might also find the plug points get eroded although you could use resistor plugs.
I have always believed you only need one resistor in a system
One between coil and distributor 5 kOhm
One between each coil and plug 5 kOhm
Or just the one for each resistor plug 5 kOhm
Not the nasty carbon core leads and resistor plugs that were fitted to my EV
I have seen spark leads installed in steel pipe but that was for safety in a petrochemical plant, large gas powered compressor motor.
.

[Old Jock]

Can't rememember where I read it Roy but I came across an article year back stating that HT wires weren't sheilded as it can lead to unwanted capacitive effects.

I'm repeating parrot fashion as I have no idea if there is any truth in that or not

John 

[Rough Edge racing]

 I was in the Army in the 60's and all the spark ignition engines had metal shielded sparkplug wires...Maybe some pilot will confirm, but don't aircraft use shielded wires also?....From actual expereince, stranded wire plug wires using a 5000 OHM plug terminal and a 5000 OHM resistor plug is usuallyy more than adequate...There maybe be exceptions of course and some may be ok on just the 5K plug cap...And whenever possible make sure ignition wires are spaced 1/2 inch from the frame or other ignition wires..

[Roebling3]

Air Force in the 60's.
Excepting commercial vehicles, painted military blue or OD, every IC engine wore braided metal shielding. It was also supposed to prevent open sparks. The insulation betwixt spark plug wires or hydraulic fluid remains as prone to failure from aging as always. Any and eventually all will act like a sparkler stick, w/out routine replacement.  R3~