Rev Counter blues on MGB

Wired back to front at the pickup.

What model does it have a pre engage starter ?

I have not touched the pick-up, not as far as i know. The counter works ok after 10 mins, it's just the 1st few miles.

The car is a 1966 MGB GT, as far as i know the starter does not look pre-engaged, I have not had it out, but it looks very much the same as the one connected to my old mk2 cortina which engaged when the starter was being turned by way on an inertia setup. I'm not sure how the starter would affect the rev counter...

Why I asked about the model is that the early models do not have a ballast resistor coil. The power to activate the 12V is usually from the engagement of the solenoid to the coil after that it runs on 7V.

the second part is there maybe a dry/loose joint in the wiring, interference till it warms up. or

You may find its just the coil, substitute the coil with a non ballast resistor type would be a good idea.

Make sure the wires are correctly positioned on the coil - positive wire off the coil, goes to the distributor on a Positive earth car. Your car (standard)is a positive earth.

If your car has been modified to a negative earth then the Negative wire will go to the distributor.

Hello Rob, the car has been converted to negative earth. The wires from the 123 distributor, red to pos & black to neg as you would expect. There is one other wire to the pos on the coil, one which runs to the solenoid. regards, Jim

should this be running to neg on the coil...., what's more if i do change it, could i damage something else?

So if I have this straight there are positive and neg wires which feed the electronics within the distributor.

There is a third wire from the distributor which is the feed to the coil to energize the coil to make it spark. This wire should go to the negative terminal of the coil. (negative earth car)

now the tricky bit - off the positive terminal of the coil there is a white wire which actually goes through a loop on the back of the tacho (for the pulse trigger )and then to the ignition switch.

As far as I know there should not be a wire off the solenoid to the coil.

if you send me an email address Ill copy the wiring circuit and send it.

photoptic (at) gmail (dot) com

rob

Hello Rob, there is only 2 wires coming freom the distributor, one red the other black.

I have double spade on the coil + terminal, other than the red one going to the distributor, the other goes to the solenoid.

I don't want to change it if i am in danger of causing damage somewhere.

regards, Jim snipped-for-privacy@wlv.ac.uk

Hi there

I see a similer thing (just fitted 123), although I just see a high reading (say plus 2000rpm) for about 5 mins after start up. Then every thing settles down.

I have the sports coil fitted but no ballast (just a surpressor).

I am gogin to try removing the surpressor.

I also notice that the voltage reg is not really working, and the rec goes mad when the indicators are truned on. I used to see this untill i fitted a new volt reg, but a run in with an inductive time light caused the problem to reappeer.

My current guess is somthing is pulling extra juice to start with 9say guages warming up and this coupled with a poss fryied volt reg is causing the problem.

I plan to change the volt reg and see what happens.

regards

Chris