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MG MGB Technical - ignition light is on 64 b

My 64 B ignition light went on whil I was driving this morning with the headlights on. The tach started jumping all over the dial.I took out & checked the generator at the auto parts store along with the battery. I put them back in, checked the wiring and started the B. The ignition light is still on. Please help.
aaron

Sounds like the voltage regulator has gone south.
Ken Lessig

Na - it ain't here!
Bruce

Suprised you have not had any good advice so far, If you look in the archives Aaron there is plenty of threads describing how to check the output of the generator and how to set the voltage regulator. It means you need a voltmeter though.
Tatty

Aaron , it is simple to test the gen. on the car , disconnect it and bridge the two connectors , connect a voltimeter to that and then start the car but _don't_ rev. it , see how much it charges , gently rev. it a bit it should immediately go to over 20 volts , don't leave it at this rate as it'll burn it out pretty darn quick . if no charge , check all the connections again and re-try it , still no charge ? gen. is dead . don't waste $ on rebuilding , the brand new ones from India work great and have better bearings . cheaper than rebuilt too .

There are repairs and adjustments you can do to the regulator but since it's acting up I'd just replace it , I bought an original Lucas one from a Ford New Holland tractor parts place really cheap , part # is : C7NN 10505-E .

Beck Arnleyn part # for the Japanese (FN) replacment one is : 177-0213

Have fun with it .

-Nate
Nate

Aaron

64 MGB originally had a rev counter driven by a cable and not a tachometer. This of course goes with the three bearing engine. Does yours have a later engine?

cheers
Ian G Buckley

The tach jumping all over the place is either second problem and a coincidence or more likely to be a bad connection somewhere around the white, which feeds the early electric tach (mid 64) and all warning lights. The battery should be more than enough to run the tach and the engine when not charging - until it runs down. Check the voltage on a brown at a fast idle and minimal electric load. 12v or so is not charging, you should see 14 or so, a bit less with headlights on.
Paul Hunt

Ian, October 1964 was the month that MG began releasing some of the later style 5 bearing cars with electric tach's. I know this because I have one, although they were often tagged as a 1965 model year by dealers.
Aaron Cohick

Aaron,

Thanks, I always thought that 1965 was the beginning of electric tachs and 5 bearings. I think some of the last pull out door handle MGBs had the 5 bearing engine??

cheers
Ian G Buckley

Indeed: 5 main-bearing engine Oct 64, push-button handle Apr 65.
Paul Hunt

This thread was discussed between 04/12/2002 and 07/12/2002

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