Yes, you should just be able to plug and play. There were various
combinations of one and two brown wires over the years, but in the case of
the 74 and the 79 even though the earlier has one thin and one thick and the
79 two thick they both go to the same places on both years and are hence at
the same potential. I could understand the thinner brown wire on the 74
having the marker as that was used as a sense wire and not a charging wire
at some point, but on the 79 the two thick wires are used to double-up on
current carrying capacity i.e. they have the same purpose. Just confirm
that the two large spades on the 74 are connected together by doing a
resistance check with an ohmmeter in *both* directions. They should both
show zero ohms. The other thing to bear in mind is that the 17ACR has a
lower maximum current than the 18ACR so as more electrical load is applied
the 17ACR will stop charging the battery sooner than the 18ACR. But
assuming a roadster with no aftermarket electrical load the difference will
probably be accounted for by not having a heated rear screen. When
connected you need to monitor the battery voltage with the engine running at
idle and switch everything on including wipers (wet screen please) and stop
lights. As long as the battery voltage stays above 12.8v it is charging.
If it is below that see just how much you have to increase the revs to bring
it above 12.8v, and bear that in mind if ever you are stuck in traffic with
everything on. In fact when stuck in traffic start switching things off
that aren't strictly needed, like put the handbrake on instead of sitting
there with the footbrake on, use an intermittent wipe if you can, turn
headlights off if you can etc.
PaulH.
----- Original Message -----
From: "MonteMorris" <mmorris@nemr.net>
To: "MG list" <mgs@autox.team.net>
Sent: Monday, December 29, 2003 11:34 PM
Subject: HIF overflow-solved-Now alternator swap
> Regarding the alternator swap from the 74 parts car to the 79;
> The one out of the 74 is a 17ACR and the one in the 79 is an 18ACR, Lucas.
> They both have the same plug, but the 79 has two large brown wires and a
> smaller brown/yellow. The large brown wire farthest from the small
> brown/yellow has a small white sleave on it; evidently a marker of some
> kind. The 17ACR has the same colors of wires in the same places, but a
> smaller brown wire in place of the white-sleaved brown one on the 18ACR.
Can
> I just "plug and play" the 17ACR in place of the 18ACR?
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