120amp altenator

I have fitted a single v belt 120 amp altenator, as others have on this forum, it shows 14+ volt on my volt meter on occasions, could this cause ecu problems as mine has just devoloped a sort of limp mode and takes many attempts to start it up.

According to the net:
Most alternators that are charging properly should produce a voltage of about 13.8 to 14.2 volts at idle with the lights and accessories off.

With mine 120A alt I see around 13.8v.on my calibrated gauge.
Check with a voltmeter, the gauge if not calibrated could be inaccurate.

I think your problem lies elsewhere.
To begin with, check if you have good spark while you are trying to start.

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I recently fitted the 120amp alternator, and I get about 14.2V at idle with everything off on my voltmeter. The car’s gauge reads about 14-14.5V. My previous alternator was around 13.8V, so I don’t see how the slight extra voltage could hurt the ECU?

Gotta be a coincidence with starting issues. Make sure nothing got accidentally disconnected in the area of the alternator.

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My lump enjoys a big old 140 amp alternator.


Anything is better than the original Lucas 80Amp!

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The last thing I did when the car was running normally was change the head light washer resovoir filler hose under the fender. So I moved the wiring of the multipin plugs and a grey box with a wiring plug going into it, and it started first turn when I tried it. Could this resister thing DAC2044 have anything to do with the car not starting.?

The resistor pack is for the injectors, so yes, if something is not right. About the only thing I would suspect would be the connector. I would at least remove connecter plug, clean the little metal prongs, and put back together.

If you were working around reservoir, isn’t that up near the starter relay? Perhaps a wire is disconnected there? On my 1988, there is a black plastic cover next to windshield wiper reservoir. Underneath is starter relay and a lot of wires. I’ve had to replace my relay already for a bad start. They get old. They aren’t too expensive new, about $80. Lucas only part. part # C36611 If yours is original, it may be worth doing even if that’s not the problem.

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Generic 30 amp relays do that job just finme.

Thanks Greg, my washer bottle I moved to under the right hand headlamp and fitted (ages ago) the vaccum tank where the old washer tank was. I will give the wiring a good clean

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Has anyone got a part number for a 120V alternator? My factory one is about to frag on me.

Thank you!
Solo out…

The one I got was from e-bay.uk and it was called ALT319
Be sure to get one that has the V-pulley included, your old one will not fit (@gregma can attest his troubles with that matter…).

Also can be found with these part numbers:
LRB00367, LRB367, 714/32200, 714/40154, 185046522, 20130212, 63320312, AL2912, AEA2291, 214120852, LRB00291, 20130195, VAP319ALT

It is also brand new, manufactured by Rollco (Rolling Components based in England). Highly recommend.

No idea about longevity, we shall find out.

Another alternative, if you’re short on time and/or wanna save money, is this starter relay used on millions of Chryslers in the 60s-70s-80s


Easily adapted to an oldie Jag. About $15-20 at most any auto parts store. NAPA number SR5



My 79 IHC Scout II used a cassic big Delco starter. No relay, Teh power came from the ignition switch directy to the solenoid. As many chevvy’s of the era, it sufferd a hot crank issue.

I swiped a relay from my son’s derelict MOPAr jalopy racer. soldered it in. No more hot crank issue.


It’s in my car for four years now and still works perfect, albeit I have only done about 3.000km.

I had installed the 100A version (Chinese Marelli clone sold by WAI); voltage regulator failed after a couple thousand miles. Put the repaired Lucas back on, works fine.
On a side note, my V8 MGB alternator voltage regulator failed (GM 10SI 37 A); priced a voltage regulator and brushes as more than a reman 63A from RockAuto-$42 less $9 for my core!
Reman GM 10SI from China, looks nice with a new pulley, replated fan, and shot blasted case. We will see if it lasts…
How can they rebuild it, replace the pulley, shot blast it, replate the fan, new case bolts (butter, one broke when I reclocked the cases) and ground/ tensioner bolt, ship it to/from China, for $33?

$33 dollars US converts to $330 dollars in China ?
Seriously, there is a reason that business move their manufacturing to China. Labor is dirt cheap. I suspect Chinese works have few if any rights, no options and no unions.

I am sure that is part of it; also I believe that the shipping is underwritten by their government so that they can compete with (read eliminate) our competition.
Problem is that most of their stuff is junk in my experience.

Also, not sure if it matters, but when I put in the 120AMP alternator, I replaced the original cable from starter to alternator (I believe it was 6 AWG?) with a 4 AWG cable.

The main reason was I went with the smaller gear driven starter, which required a slightly longer cable. Figured I’d up it to 4AWG while there.

Thanks for the input, gang!