My problem of misfiring was traced to my Lucas Distributor exhibiting shaft
wobble, almost from new, but getting much worse by 15,000 miles.
The Lucas dizzys are well known for this problem due to their somewhat
primitive design.
The Lucas dizzy was fitted with a Pertronix which helped some, I also fitted
Magnecour 8.5mm TR6 wires, (on my Vitesse), which helped, then an MSD Digital
6 plus box, (I bought it on vacation in CA because the speed shop was out of
MSD 6AL's at the time.
It is a terrific unit and is mounted inside my RHD car, on the front
bulkhead, immediately beneath the battery.
I also fitted an MSD Blaster 2 Coil. and I have been using NGK Platinum
BP-6EV spark plugs, and now I am trying out the new NGK Iridium
BPR-6EIX spark plugs, (no incredible improvement but they are much harder and
should last much longer) - best price found so far, from Rockauto.com on-line.
This all worked together rather well, except that the Lucas, (Bosch
reproduction), distributor caps did not seem to be made of the same dielectric
material
as the original Lucas items, and the modern reproduction rotor arms are
pinned together, pieces of junk c/w to originals! The alloy contacts inside the
caps seemed to last around 2,000 miles or so, and they showed signs of burning,
and uneven wear which indicated shaft wobble.
I went over to a Mallory Distributor, stealing the drive cog, washer & pin
from a spare Lucas distributor.
Mallory do not list a distributor for the TR6 type engine, but they do list
one for the Jaguar XJ6, (Thanks Steve Smith), nor do they list one for the
Spitfire, but they do for the MG Midget 1500...typical!!!
The cheapest supplier for both being Summit Racing.
Part numbers # 2367801 (TR6), and 2332001 (Spitfire).
Best way in is to buy the dual points, no vacuum advance distributor, then
you can either run it with the points, or convert to the appropriate Pertronix
unit.
Early TR owners will have to talk to Mallory.
MSD aren't apparently interested in making distributors for our old furrin
cars.
The best things about the Mallory distributor are no shaft wobble, a bigger
cap and rotor, (less chance of cross-firing), and copper contacts inside the
cap.
The above is all powered by a red top Optima battery, following advice of
this list), and recently a Bosch/Autolite Alternator putting out 61 amps, which
has to be better than the Lucas 34 amps.
Hope this info is useful.
Leon F Guyot
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