MGB Roadster 1980
The symptoms are as follows:
ignition warning light not on when ignition turned on and engine off
with engine running light glows slightly until engine revs reach 2500 revs (this value is rising as the days go by)
when light goes out (above 2500 rpm) the clock goes very fast and second hand whizzes round
voltage is around 12.5v at all times dropping to 12v when headlights on irrespective of engine running or revs
have done 200 miles, battery charge seems fine
Is this just(!) a duff alternator?
TIA