How to fix a wayward rev counter?

[big h h]

any ideas how to fix a wayward revcounter that has a mind of its own.

[ph1l5]

Have you changed your Y piece recently ?
My rev counter was jumpy and I found that after I had refitted the Y piece to stop a blow it cured the rev counter issue.

[blitzracing]

Running Magnecores by chance? If so throw them away and replace them with normal resistive HT leads, or fit resistive plugs.

[gruffalo]

Do the Chims have a 100amp charging fuse, if so take that out and have a good look, on Cerbera's it is a common cause of erratic tacho's.

They crack with age and heat, look ok until you take them out.

[QBee]

gruffalo said:

Do the Chims have a 100amp charging fuse, if so take that out and have a good look, on Cerbera's it is a common cause of erratic tacho's.

They crack with age and heat, look ok until you take them out.

Yes, they do. It's due south of the alternator, fixed near the chassis rail under the car in a holder. Small socket spanner, 8 or 10mm from memory, and the Gruffalo is right, you need to unbolt it to make sure it isn't cracked.

On the plugs front, any 6 or 7 plug with an "R" in the description will do. I went to BPR6IEX, which are iridium, so last a lot longer. Car runs better on them and with a 6 plug there is less risk of them fouling if you don't use the car for regular long blasts.