Talk Morgan Forums Morgan Sports Cars Maintenance & Servicing Alternator For +8

I am thinking of replacing and upgrading the original old alternator on my 94, 3.9 +8. Would like to put in a 120amp alternator does anyone have any recommendations?

Sideways recommendation

Access on mine was dreadful so I cut a matching vertical hole in the inner wing. Made the job significantly easier, have Pic if you want it

Is there need for such a large capacity alternator Bruce? If you have unusually high electrical loads I can maybe understand otherwise not. For example I had two nominal 12 volt alternators on my narrow boat totalling 250 amps but they had to re-charge a total battery capacity of over 900 amp hours (nearly twenty times your battery capacity) most being the service bank in use in the evenings when engine not running and no shore power.

The ideal charge rate in lead acid batteries is C/10 for greatest longevity, where C is the battery capacity in amp hours and charge rate measured in amps. Expediency can justify higher rates up to C/3, being a balance between reasonable longevity and limited re-charge time.

Another example is my 60 year old diesel Land Rover which manages with it's OE 22 amp dynamo, it's 10 year old battery still going strong. I admit this is marginal though and a sop to originality

A modern alternator suitably geared to charge at fast idle close to a max output of 50 amps would be more than adequate surely.

Richard; thank you for the advice you are correct I was over thinking the capacity needed, I'm sure there is a medical term for that or maybe it's because I'm slowly becoming American!!!!

Wise decision. The MMC stock alternators were complex, expensive and feeble. Most importantly, they are too hard to find, too much
so for a regularly used Morgan with a modern draw. I agree with you, one needs at least 100 amp and up. IMHO

I match such components to the mogging area. I chose one-wire Densos in North America and Bosch for UK/Europe. These units can
be found at any roadside mechanic's on a slow Sunday. There is no reason to ruin your Morgan day. They are super reliable and cheap.
They are also more compact and metal rather than plastic covered.

If you are in the North America, buy a rebuilt Denso, which is a better choice than new, and can be found.everywhere. JEGs, Summit,
eBay for a 1/4 of the price of less worthy fare. You will need to have a small bracket fashioned and I have the designs up on gomog

Many people have trouble removing the alternator. It becomes easy if one removes the Morgan bespoke bracket and the alternator together.

Good luck!

Lorne
.

Cheers Lorne

Similar topic or question but:

There is a malfuncton in the alternator in my plus8, 3,9l from 2001 resulting in that the voltmeter shows null and the battery is not charged.

Any idea about the reason and how it can be fixed?

Any suggestion about a replacement alternator and if so manufacture and model/type

BR. //.  Haakan in Sweden

Hi Bruce!


Hello Haarkan, Firstly, are you sure your Plus 8 has a 3.9 (Hitachi Hotwire) rather than a 4.0 (GEMS). This will be cast into the top left of the plenum chamber, the big mushroom thingie atop the engine and what colour is yours? It can also be confirmed by whether you have a distributor or not..front left of the engine block Looking from left hand side of the engine bay.

Additionally, can you check the tightness of your fan or serpentine belt? It could be old, loose and slipping. Quite common.

Lorne