Alternator

The alternator in my MGB is pretty much stock - a Lucas model that generates about 35 amps. The alternator is not the original, its been replaced at some point, but alternators don't last forever.  Recently, I have suspected that my alternator was on its way out.  The ignition light would stay on after the engine had started and then go out only once I started driving.  A steadily burning ignition light indicates that the car is drawing from the battery - and the alternator is not generating enough power to supply the car's needs.  

I have two voltmeters - the in dash meter which although it looks nice, is slow to register and not very precise and a plug in voltmeter that plugs into the cigarette lighter.  The plug in meter is digital and very precise.  
You can buy them at Walmart - they're really cheap and well worth getting. The voltmeter was reading for 12.3 V up to 13 V although occasionally it would hit above 13, but never over 13.5 V.  Most of the time we were in the sub 13 V range.  This is pretty good evidence that the alternator is not doing too well.  So I decided to replace it.

There are several choices for replacing an alternator.  The basic choice is a refurbished Lucas model.  This is the simplest solution, but not the best.  The basic Lucas model generates about 35amps - a charge rate that is pretty low compared to model alternators.   

The first commonly used alternative is from a 1980 Ford Fiesta.  This is in the 60 amp range and bolts on pretty easily by all accounts.  Finally, you can use a 1991 Saturn alternator that generates 96 amps and will power anything that you could ever want to run in your car!  The problem with the Saturn alternator is that it needs a different pulley and slight mods to the wiring.  But free enterprise is a wonderful thing and where there is demand, someone fills that demand and makes a buck and that's exactly what the owner of http://www.mgccars.com/ did.  I bought my new alternator from him - here's the link:  http://www.mgccars.com/96_amp_alternator_upgrade.htm.





The alternator arrived quickly and was nicely packaged with clear instructions.  
The alternator bolts on and there are just two wires to connect.  
I charged the battery and installed it this afternoon.  
When I started the car up, the voltmeter showed close to 14.5 V charging.  
When the lights were on and I taxed the system, the volts were still 14.3.

This is a great upgrade for your B and well worth doing.