Bouncing tachometer

[T5GRF]

I have noticed that the tachometer needle bounces around when changing up or down the 'box, is there some deep and meaningful reason for this or generally is it a case of perhaps it's a bit worn?

[PH430]

I had it to, but i found it.
Worn exhaustmanifold gasket. The bangs in the manifold can effect the tachometer needle going up and down by the ignition module on the dizzy.

[T5GRF]

Thanks that's really helpful. I don't suppose you had any intermittent idle speed problems at the same time?

[Sardonicus]

PH430 said:

I had it to, but i found it.
Worn exhaustmanifold gasket. The bangs in the manifold can effect the tachometer needle going up and down by the ignition module on the dizzy.

[Chuffmeister]

Have you changed HT leads? Using Magnecores? Try changing or rerouting the king lead. Low resistance leads suffer from more interference, which affects the signal to the tacho.

[PH430]

Sardonicus said:

PH430 said:

I had it to, but i found it.
Worn exhaustmanifold gasket. The bangs in the manifold can effect the tachometer needle going up and down by the ignition module on the dizzy.

When you have the TVR Bible, you will read it on the artical of the tachometer. I was also supriced.

Had also some idle problems at the same time.
Yes indeed i have the magnecor leads

[Sardonicus]

PH430 said:

When you have the TVR Bible, you will read it on the artical of the tachometer. I was also supriced.

Had also some idle problems at the same time.
Yes indeed i have the magnecor leads

Oh I am not surprised I am gob smacked its bks