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MG MGB GT V8 Factory Originals Technical - Alternator Pulley - Factory V8

Hi all,

I've had my Factory V8 for a couple of months now steadily eliminating faults here and there. She runs very well now but I have a charging problem. I purchased a rebuilt alternator but unfortunately it was assembled with the mount for the adjuster bracker on the LHS instead of the RHS so I can't use it. It seems they are rare as hens teeth over here. In the meantime, I noticed that the pulley of the replacement is much smaller than the pulley of my current alternator.. Could someone with a Factory V8 please measure their alternator pulley and tell me it's diameter?

I am thinking that my charging problem could be simply that the pulley is too large! My alternator puts out just under 13V in it's current state and I get a very very dull glow from the ignition light under some circumstances.

I'm off for a trip over to the UK in a week and will be at the MG show on the 18th, let me know if any of you will be there to say hi to! :)

Cheers,
Neil
74 V8
Neil Cotty

Neil,
I just ambled out to the garage and measured my pulley - I have the original Delco alternator on my Factory V-8. The diameter at the outer edge is just about 2-7/8 inches (73mm). This was real easy since I don't have the bonnet on the car yet - that's one of the last bits to be painted and installed.

I put a new old stock Delco alternator on when I rebuilt the engine, and I noticed that it did not begin to charge until I revved the engine fairly high once or twice - when I first started the engine and ran it at a steady 2,000 RPM for initial break-in, the alternator light stayed on. It wasn't until I "goosed" it a couple of times that the light went out. The pulley on both of my Delco alternators is the same diameter.

Do you have the original Delco, or has someone swapped in a Lucas alternator? That may explain the difference in pulley size.

Hope this helps,
Cheers,
Paul Kile
Paul Kile

You can swap the adjusting lug to the other position by undoing the three through bolts and rotating the front cover in the desired direction!
Chris Betson

Hi Neil, Hi Paul.

Mine is also a Delco but I have no idea whether it is original or not. The outer diameter of the alternator pulley is 2.95" and when 'in the groove' the back of the belt is about 0.15" down from the outer rim. It should still put out close to 14v even with the incorrect pulley, although though it may give a lower max output than it should. Dim ignbition warning lights can be caused by bad diodes in the alt, bad connections from alt to the rest of the system (toe-board stud on my 75, not solenoid), or bad connections in the brown - ignition switch - white circuit. If you only measure 13v right at the alt terminals (connector plugged in!) it is the alt.

PaulH.
Paul Hunt

Paul K,

A common issue with 'new' alternators, especially those which have been rebuilt of stored for long periods is that they take a few miles use to 'bed' in before actually reaching optimum working efficiency.

Rog
Roger Parker

Hi all,

Many thanks for the help everyone. Would you believe I haven't been able to measure my pulley yet as having just moved to Ireland I don't even own something as simple as a ruler!!!! <VBG> Ahem! Will report back though, and yes it is an original Delco (but rebuilt) and so is the replacement.

The old alt is putting out just under 13V - at the alternator, so I guess it's on it's way out. Chris - I removed the three bolts the other day before I posted to the BBS, and when I turned it, something broke inside! Even when I put it back in the original position it didn't turn the same again. Unfortunately I have well and truly stuffed it! How I am not sure.

I will try and pick up a new one when I'm at Stoneleigh on the Weekend. Hope to see Paul H./Jeff Z./Roger P. there too! Anyone else from the UK going?

Cheers,
Neil
Neil Cotty

At this rate we will have to design a BBS hat ...
Paul Hunt

This thread was discussed between 10/02/2001 and 13/02/2001

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