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C130 Alternator Upgrade

June 06, 2020 10:31 AM | Bob Chalker (Administrator)

by David Terry

The Problem

Driving my MGB at night using either the auxiliary lights, overdrive, or fan would cause the ignition light to glow, indicating that the battery was augmenting the alternator to power these items. Resolving this issue would require an alternator that generated sufficient power in excess of what the original Lucas 18ACR could provide.

The Remedy

First, I needed to charge the battery. Since the previous owner (PO) had reworked much of the engine bay with nonstandard wiring colors, I had to trace the wiring against a wiring diagram.

I ordered a CS 130 alternator from 123ignitionusa.com and removed the Lucas alternator. On installation, I cut the plug off of the existing alternator (I cut it about two inches below the plug), then connected the brown and yellow wire from the loom to the brown wire on the new alternator plug. The next steps were:

·       connect the medium brown wire from loom to battery post on alternator

·       connect the red wire from new plug to battery post on alternator

·       connect thin brown wire from loom to battery post on alternator.

Finally, I installed the fan belt and tensioned it appropriately and started the car. The PO had connected the wires from the ignition relay to the Lucas alternator rather than the battery post on the starter. Once I was able to address this anomaly, connecting the wiring was easy. The new alternator now generates sufficient electricity to power the headlights, overdrive, wipers, and aux lights at night without causing the ignition light to glow. My headlights have never been brighter.


Upgrading from the Lucas alternator to the CS 130 was an easy project that took about thirty minutes to complete but resolved the power issues I was experiencing. If you are interested, order from Ed Madak at 123ignitionusa, LLC. The unit comes complete with pulley and ready to install. You may have to adjust the spacer provided to align the belts but, again, this is straightforward and easy to accomplish.

A big THANK YOU to David Terry for submitting this article. It will be a benefit to many of our members and followers.  If you would like to submit an article to the ROARS, either technical or social, please do, we are always looking for content.  Don't worry about your writing capabilities our editors, Dave and Linda Renner, will work with you to make it stellar.  You can submit articles by sending them to HoustonMGCarClub@gmail.com

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