View single post by Mark Rosenbaum
 Posted: 05-18-2006 09:41 pm
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Mark Rosenbaum

Joined: 03-12-2005
Location: Kingman, Arizona USA
Posts: 532
Jim DeClerck wrote: This design feature of (later model?) Jensen Healeys leaves one wondering, "What were they thinking?".  I assume earlier cars were equipped with Delco alternators and that later it was decided to change over to the Lucas unit.

Is it known at which VIN. # they made the change? 

Judging from what I see in the parts list and shop manual, it appears that Lotus provided engines with the alternator already installed.  If so, then probably Lotus, not Jensen, was responsible for the change.  Perhaps it was just a matter of British chauvinism, perhaps the Lucas part was cheaper, or perhaps Delco wouldn't sell alternators to Lotus for some reason -- hard to say at this late date.

If I'm right, then the question should be, "at what engine number did they change from Delco to Lucas?"  In this regard, the shop manual indicates a change from the 45 amp Lucas 18ACR to the 35 amp Lucas 17ACR alternator at engine number 9815.

Is it feasible to connect a separate permanent cable from the battery +12v side to the Lucas 1/4" alternator exciter terminal to ensure charging of the battery without doing damage to other operations of the electrical system?

Don't know.  As mentioned earlier, I'm not familiar with the Lucas alternator.  All I can suggest here is to try it with a temporary hookup.  If things work, make the wiring change permanent.  If not, you're probably no worse off, though I suppose it's conceivable that the alternator might be damaged as a result.

Another question:  I installed a good bulb (Peanut 2V) in the heater console light socket and it shines when I turn on the head lights.  But when I check the voltage at the 1/4" female spade connector which would connect to the exciter spade on this Lucas alternator I get almost 0 current (0.03V).  Shouldn't it be 12+ volts?

The IGNITION light on the heater console should illuminate only when the ignition switch is in the RUN position and the alternator is not providing a charge.  The status of the headlights should not affect this at all.  You may have a previously unsuspected wiring fault.

The bulb itself needs to have about 6 volts across it to illuminate dimly, and 12 volts normally, so 12 volts on one side and 0.03 volts on the other is to be expected.  The 0.03 volts is the alternator's output voltage at this time.  When the alternator begins to function, its output quickly reaches then slightly exceeds the battery voltage.  This normally happens so quickly that the bulb filament is still hot and producing light even though there is very little voltage across it.  And finally, when that occurs, the bulb rapidly cools off and extinguishes.

If all else fails, your local Kragen auto parts store probably has the ability to test it for you.  This is generally free, either as a matter of promoting customer good will, or because  they think you might buy a replacement from them should you need one.