Ignition Warning Light Suddenly On - Alternator?

No, shaft diameter is 15mm on Lucas, 17mm on just about everything else (including Marelli used on Land Rover, and GM). Look up my post on Marelli 100A that I installed recently; GM pulley works with minor lathe work on hub to clear the Marelli case. You need to match diameter to Lucas to maintain charge at idle.

WAI 13697N; brand new on Amazon for $112
The pivot bolt is correct diameter, may require adjustment of the pivot ear to bracket shim thickness to align belt. Comes with a serpentine belt style pulley (17mm shaft); I replaced it with a WAI single groove 67mm pulley (2411001) which is for Delco and Ford alternators- had to cut about .020” off of the hub OD and .050” off of the rear face on the lathe for clearance. Adjuster will require shimming where is attaches to timing cover, because adjuster ear on the alternator is thicker; also will need a longer bolt in that location. Had to also trim the output wire eyelet to clear the plastic terminal divider. Works great, pulley is slightly smaller than the Lucas, so alternator is turning about 50RPM faster at idle.


70mm for 10mm belt is OE Lucas.

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Thanks so much Robert. I have ordered it. Very close to original Lucas. And I can say my Jaguar has a Pontiac part on it! :wink:

Well, late to this party, but I was gonna recommend you go with a size larger diameter than the minimum. You really don’t need the alt spinning that fast; these modern alts charge very well at low RPM, much better than older alts. And a larger diameter doesn’t bend the V-belt as tightly and has more contact area for less slippage, meaning you don’t have to keep it so tight.

I’ve gone ahead and ordered this one too, exact same dimensions for belt and bore, but it’s 74mm (2.91") instead of 67mm (2.64"). Original Lucas is 70mm (2.76").

Which ever one fits the best.

In the reality of it, we’re talking about 1/8" diameter difference either way, which is only 1/16" radius. Can’t believe that would make much difference??

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So I did a bit of research on the GM CS130 that The Book and many here have adapted for their V12s over the years. I’m starting to wonder why that one?!

Seems that the CS130 has a bad rep for overheating too easily and prematurely going bad. I assume putting it under the hood of a V12 would only make it worse. There IS the Iceberg update, which improves cooling and also increases bearing size. Maybe that is all that’s needed? Then there is the CS130D, but that has the regulator that will shut off charging if too hot. Not an issue? It also looks a bit bigger, so may not fit as easy?

I like the idea of finding a better alternator as a few did here with the Land Rover. I’ll be installing that where OE Lucas is next weekend. One day, I may see if i can fit mine to smog pump bracket once i put back A/C compressor.

There’s gotta be more reliable choices than GM CS130?

Got the Land Rover alternator (100 amp beaut), and a GM V-belt pulley. Looks like inside disc on pulley that fits inside alternator casing needs about 1/16" taken off for it to clear housing. (Just like @RGK20m3 Robert mentioned) Oh to have a machine shop!

I’ll be getting the slightly larger diameter Hitatchi pulley Monday. Will report how that fits then.

Oh, and I “think” the OEM of Land Rover alternator is Marelli?!

Correct, original LR alternator manufacturer is Marelli - one that I bought was WAI replica (US distributor for made in China). Seems well enough made and working well.

It won’t. I was suggesting going for one perhaps an inch larger. I had no idea they’d be available in such tiny increments.

I understand, but the serpentine pulley that usually comes with this Land Rover alternator is about the same size as the Lucas one and the one I’m buying. I would think it’s more important to stick to the pulley diameter that the alternator was designed for.

Question about fitting V belt pulley to this alternator.

The disc bit sticking out of pulley needs about 1/16" or less taken off circumference so it fits inside housing hole around shaft. But if big side pulley then rubs with housing, do i simply put a couple washers in there to push it out a bit?

What exactly did you end up doing @RGK20m3 ?

You will have difficulty finding 17mm shims; I checked McMaster-Carr, on line, and the local hardware places. I did buy some alternator pulley spacers online (OE Delco), but they space the pulley too far out (.200”).
I had the pulley machined; about .020” off of hub OD, and .050” off of pulley face if I recall. Ended up with good pulley alignment fine tuned by adjusting washer thickness between alternator front ear and bracket.
By the way, pulley diameter is critical if you want it to charge at idle. 2mm difference is about 50 rpm, 3” would result in no charging until 1500 rpm.

Not really. We don’t know the size of the crank pulley on the Land Rover. And we don’t know the redline of the Land Rover engine.

One of the first things racers do is replace the alt pulley with a larger so the alt turns slower. Racers generally have the engine revved higher than street drivers, so there’s no problem with turning the alt fast enough. And the electrical loads are typically pretty low in a race car.

Certainly not true in the case of the CS130. The pulley I used was at least 3" because it was being driven by a 5/8" V-belt, not a 1/2" as an alt typically sees because it was in the air pump position and served as an idler for the A/C compressor. Charged just dandy at idle. That’s one of the great things about modern alts, they charge much better than older alts at idle. A couple of the earlier Delco designs were famous for not charging at all at idle, and modifying them to produce more amps at speed made them even worse at idle.

Alternator belt on the Lucas equipped V12 is 10mm wide; pulley that I used is for a 10mm belt, so diameter difference directly affects alt RPM. I know on mine that the alternator keeps up with the condenser fan and HVAC blowers right at 650 engine RPM- if it drops 50 RPM, the rate falls off and can be seen on the voltmeter (and heard in the blower speed).

I could probably find 17mm alternator pulley shims, but the width has to be quite narrow which may be hard to find. I could stack enough to equal your 0.05". That would put pulley out a bit further than yours, but didn’t the alternator bracket need to be shimmed to push out pulley a bit anyways to fit belt?
Machining back face of pulley seems like a good backup plan if its only 1.27mm (0.05")

Thanks for your info, much appreciated!

Seconded, you beat me, Kirby////


I recall Hoppy AAron’s dirt track racer. Did not bother with an alternator. Actually a generator at the time. Just brought two fully charged batteries to the track/ 1/4 mile/ One for hot laps qualifify trophy and heat. The other for the main. His 35 Chev coupe turned roadster powered by a hot Mercury was hard to eat. Hoppy was a durn good chaufer. One time motorcycle flat track racer. Hence his nick name . Real name, Ezra…

Another alternative that I considered was to disassemble the alternator and grind the case for clearance to alleviate the need to machine the pulley; problem is that the stator wires are crimped then silver soldered…

Unlimber the grinder and gently grind away the small amount. with care so as to not disturb any balance.

Or older tech. Flat file.