HT Leads

Yer basic silicone HT lead. I'd always though of 'HOTWIRES' as a gimmicky name when I saw it advertised, and was surprised to find the basic black leads I had bought from the MGOC were the same as these from Halfords.

At first sight appears to have a single-strand resistive inner trapped under the crimped connector ...

... but cutting diagonally through the cable shows it as many very fine strands which seem to have an outer coat bonding them into a single conductor. Each strand is conductive.

Construction

After that the sky is the limit as far as construction, claims and price are concerned. There are many that have a spiral wound steel conductor, which may have the central core as merely a strengthening device, or may be an additional resistive conductor such as in the basic silicone leads above. There is even one (at least) with 'capacitors' and braided earthing straps.

Magnecor have published an interesting document 'The Truth About Ignition Wire Conductors' that is very scathing about the claims made by many of these 'high-performance' aka highly priced leads. It includes the following statements:

In effect, (when new) a coated "low-resistance" spiral conductor's true performance is identical to that of a high-resistance carbon conductor.
... a test performed by Circle Track Magazine (see May, 1996 issue) in the USA, show that NO "low-resistance" ignition wires for which a horsepower increase is claimed do in fact increase horsepower - the test also included comparisons with solid metal and carbon conductor ignition wires.
Claims by Nology of their "HotWires" creating sparks that are "300 times more powerful," reaching temperatures of "100,000 to 150,000 degrees F" (more than enough to melt spark plug electrodes), spark durations of "4 billionths of a second" (spark duration is controlled by the ignition system itself) and currents of "1,000 amperes" magically evolving in "capacitors" allegedly "built-in" to the ignition wires are as ridiculous as the data and the depiction of sparks in photographs used in advertising material and the price asked for these wires!
Unless you are prepared to accept poorly suppressed ignition wires that fail sooner than any other type of ignition wires and stretch your ignition system to the limit, and have an engine with no electronic management system and/or exhaust emission controls, it's best not to be influenced by the exaggerated claims, and some vested-interest journalists', resellers' and installers' perception an engine has more power after Nology wires are fitted. Often, after replacing deteriorated wires, any new ignition wires make an engine run better. (My emphasis as that goes for anything on an MGB)

Having said all that Magnecor produce their own range of wires from copper upwards, with prices for the MGB GT V8 ranging from Ł97 through Ł113 to Ł153!! You can get OE GHT107 from ANG for Ł12 (other sets for side-entry and RB), or a set from Clive Wheatley for Ł35 and that's the highest I would go ... if I really forced myself. Of course the same price differentials and sources apply to leads for the 4-cylinder, substituting any of the usual suspects for Clive as he doesn't supply parts for that engine.

HT Lead Positioning

Showing how the 4-cylinder column UJ clamp bolt had gouged the rubber boot on the HT lead when it came straight of the cap to No.4 plug, probably not far short of causing a misfire. Wrapping it under the cap and the other leads holds it out of the way:

However there are lead sets with right-angled cap connectors (GHT106 for 25D4 and GHT184 for 45D4) that should solve the problem and are only Ł14 and Ł19 respective, I don't know how they differ.

Angled connectors fitted to the MGOC right-bank silicone leads for the V8:

Separate leads 5 and 7 in the combs with lead 3 to prevent possibly parasitic ignition in cylinder 7 when 5 fires. Note the Leyland Workshop Manual Supplement states the direction of rotation incorrectly but the drawing of the firing order is correct: (image from Leyland MGB GT V8 Workshop Manual Supplement)