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5 mm difference in diameter should make no difference apart from slightly increased idle charging, Jochen. And the new alt may have a higher rating than the previous one…
As an aside; the voltage readings will vary with battery state - a fully charged battery will get higher readings…
Frank
xj6 85 Sov Europe (UK/NZ)
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Jochen:
I’d count that as a win. If you don’t run for long periods at red ;line, the smaller pulley will do just fine.
And, now, you can examine and over haul the original at your “leisure”. Spare parts seldom a bad thing.
Carl
Indeed Carl,
the car is running and will take my son and me skiing over the weekend. I guess that’s worth the money invested into an extra alternator.
In the meantime I’ve opened up the last one to find that a Lucas 15TR regulator is installed which I still have to source. While I’ve found a SIII parts book with a picture of DAC3480E as installed in my car,
I don’t have instructions about overhauling this piece of machinery. There should be instructions in the SIII ROM though. It would be great if anyone could send me a copy or put it on the forum.
Thanks again and best regards
Jochen
75 XJ6L 4.2 auto (UK spec)
Hello all,
as promised I just wanted to report back after an extended drive (140 mls round trip with three persons, luggage, ski rack, including motorway constant speed 70-80 mph, some mountain driving + 36 h parked outside with serious rainfall):
The car behaved flawlessly, didn’t miss a beat, started right up for the return trip. Voltage hovered around 14.1 V (measured at the cigar lighter) even at 3.800 RPM.
And a Joseph Lucas kind of miracle occurred as well: The rear heated window resumed work on the trip back. Those of you who read the beginning of the thread may remember that the voltages surges started after my fiddling with the rear heated window switch. Both occurrences may have been coincidental and unrelated, but it’s still strange enough … I’m not sad about it though.
Have a nice week and
best regards
Jochen
75 XJ6L 4.2 auto (UK spec)
Done, before someone else also does: glad to help where I can 
Thanks again, David!
