MGB rev counter.

[spoodler]

Any advice please? The revcounter needle on the NG swings rather wildly from about 2000 to 5000 under normal driving, and from about 500 to 3000 on tickover. It's purely the revcounter not erratic running. It's an MGB non-cable/electronic type. Any ideas whether it is likely to be a voltage regulator, earth (fibreglass body), or similar or if the gauge itself needs work? It has been like it since I bought the car.
Any one have any comments or suggestions before I go delving as a health condition makes working under the dash unpleasant at the moment.

[manek]

Some help here: http://www.mg-cars.net/mgb-technical-bbs/voltage-s...

[spoodler]

Thanks. They are pretty much saying there what I suspect is going to be the case... it'll have to wait until I feel better. Who needs a rev counter on a B Series lump anyway?!

[spoodler]

Cheers for that, but no it's a good old mechanical points set up.

[v8250]

Do you have an early current sense tach, or the later pulse sense tach? You can tell by the gauge dial type. Once known, check your wiring from the coil and the earth/ground connection, replacing with new wires if necessary. If unsure as to the wiring layout check here for reference

https://www.google.co.uk/search?q=mgb+tachometer+w...GogSjc93n6AXkp-nmYoLM_ITirM%3D&ved=0CDYQyjdqFQoTCKvlkYbptMcCFQaC2wodKAUDJQ&ei=skrUVavEB4aE7gaoioyoAg#imgrc=qZv6aLkp93UcrM%3A&usg=GogSjc93n6AXkp-nmYoLM_ITirM%3D

Also, some MGB guys experience similar problems where there's a resistor wire built into the MGB wiring loom. Check to see if your coil is ballast or not as the ballast can throw up spurious faults.

[spoodler]

Thanks for the comments - I'll let you all know if I sort the problem, not raining at the moment so might get something done.

[Hooli]

What sort of NG? I think I'll be rehoming the TF my dad no longer drive at some point next year.

[spoodler]

Mine's a TA - bought it as a stop gap until I get the hot rod back on the road but it has really grown on me. Tend to use it to make up for the fact that I can't do distances on the bike at the moment (nor camp with minimal kit), so what might have been a biking holiday around the Lakes became an NG holiday and, to be honest, was just as enjoyable.
When you want to get shot of the TF give us a shout as I'm in contact with a few interested folk and may be able to help find a home for it.

[Hooli]

I think we're keeping it as Mrs Hooli likes it, but cheers anyway.