Fellow fiends:
I think I might perhaps sort of maybe kind of possibly solved the misfire
problem on the '63 B (hereafter, known as "old white"). Despite valiant
efforts to check carb settings (repeatedly); fuel supply; plug, wire,
vacuum, and points conditon (repeatedly); timing (repeatedly); and valve
clearance; the problem persisted (...repeatedly). Until, that is, I swapped
the coil on my '67 e-type. Then: all is heaven, angel trumpets and devil
trombones!
Simply a "bad" coil? No, not according to my local auto electrics
information source (who prefers to remain nameless in the event of a law
suit). As it turns out I had mounted a coil that required 1.5 ohm
resistance in a car that was not set up for such. This type of coil was
used on later MGs ('75-bitter end, I think), with the intention of providing
extra power during starting. On cars so equipped, in the normal running
circuit into the coil there *should* be a resistor, dropping the voltage
from 12 down to 6 or so (rumor has it that the resistance was so slight they
just used several feet of wire). The ignition switch would bypass this
resistor (i.e. take a short piece of wire) and temporarily the coil would
really belt out the volts (to start up a cold engine), being supplied with
12 now instead of the ususal 6. The higher than normal volatage into the
coil during these very brief bouts supposedly wouldn't damage the thing. As
the ignition switch was released, the circuit would switch back to include
the resistor and the coil would run happily at its lower than 12V rating
(usually 6-9, so I am told) providing an adequate spark to keep an engine
running. Well, if you *don't* have such a resistor containing circuit then
the coil is running at 12V all the time. A coil suitable for such a
"non-resistor" circuit would be happy. The other type cannot handle it for
very long. The coil eventually will "burn up," probably taking the
condenser and/or points along with it.
So, in my case, so the theory goes, the coil lasted for about a week before
the effects of chronic 12V supply started to take its toll. That is,
gradual coil failure, weak spark, and... MISFIRE! Indeed, right there on
the coil, next to "12V" it says "use 1.5 ohm resistance." How was I
supposed to know? I'M AN IDIOT! I looked back on my parts orders and I
sincerely believe I was sent the wrong coil. On the other hand, I should
have made sure I understood what the advice about a 1.5 ohm resistor was all
about.
Many thanks to the SOL'ers who responded to my repeated inquiries. This
list is okay!
Will "live and learn" Zehring
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