>Hi all,
>
>(the real question is in the fourth paragraph)
>
>I experienced an eventful Easter weekend in which my Voltage
>Regulator blew (again), my generator broke down and my batterie got
>empty, so I was left at 2.00 a.m. in the night needing 'SOL roadside
>asistance'. (For the first time I was happy a was a member of the
>Dutch 'Roadside Assistance')
>
>After reloading the batterie (a single 12 V, that is) I still managed
>to drive 200 miles to my destination (carefully not using lights,
>wipers etc.).
>
>I replaced the VR and checked my generator according the Haynes
>manual and found out that it didn't work at all. So I'll need a
>rebuild generator (the bearings were shot anyway).
>
>But apart from this slight nuisance ;-) , I encountered some other
>thing. When the engine revs above, say 4000 rpm, the tach starts to
>swing wildly up and down sometimes reaching 0 and then again to 6000
>rpm. This happens with O/D engaged or not engaged.
>The engine performs flawless with these high rpm, at least I don't
>notice any sputtering or an indication that my ignition is not able
>to supply sparks to the engine.
>What is the problem?
>
I had exactly the same situation 3 years ago. Hopefully it is the same
problem. It was simple to fix. Even though I had just had my engine
professionally rebuilt, and the mechanic, whom I still trust, claimed it
couldn't be an issue, the problem was a narrow point gap. Your tach reads
off the frequency of the coil, and if the gap on your points narrows down,
you get goofy readings in the upper rpm area. Usually won't jump around
under hard acceleration though, and I don't know why. Even if you just set
the points, go back and check them, and if you have one use a dwell meter.
Good Luck!
Phil Bates
67 MGB
75 Jaguar XJ12C
52 MG TD replicar (VW)
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