In article . com,
wrote:


There are only 2 types of RF supression wi resistive and inductive.
The latter is often referred to as "magnetic" and is widely available,
but it doesn't seem to work any better than the resistive type. A
significant amount of igniton noise comes from the connection between
the plug and the plug wire, and grounded metal shields over the boots
can help here. There are wire kits with these boots, mostly for German
cars, or they can be made with metal tubing slipped snugly over the
metal bases of the plugs.

I recommend getting a copy of the ARRL Hints and Kinks for Radio Amateurs
book... get one of the mid-fifties editions and there is a whole section
on eliminating ignition noise with homebrew shielding over the plug wires
and shield cans over the distributor.

I agree that with modern resistive wires, things will be a lot better. Back
in the fifties, plug wires were normally copper. Often folks would buy it
on long rolls and terminate it in the shop themselves. Today, plug wires
have a conductive element that is conductive plastic, usually a nylon with
carbon in it, and the wire itself has a few kilohms of resistance. That,
combined with a modern coil design, means you get less high frequency ringing
after the initial spark impulse which cuts way down on the noise.
--scott

--
"C'est un Nagra. C'est suisse, et tres, tres precis."