Tachometer

[Peter Bell]

The rev counter on my car is playing up, it is the 'old' type with a feed and return to the coil. It started showing the wrong revs as I was driving and now shows 7000 at tick over. I tried fitting a different one (not sure if it is a good one) with a single feed from the coil and it does the same thing. The engine runs fine, anyone any ideas of what is going wrong?

Thanks Peter.

 

Should have added it has a bosch dizzy with the hall effect trigger. and been running ok for 6 years!

[Guest Ant]

it is the 'old' type with a feed and return to the coil.

 

I could be wrong, but I didn't think any rev counters ever had a feed and a return to the coil. My rev counter is of 60's vintage and it has a negative feed from the negative side of the coil, a 12v feed which is permanently live as long as the ignition is on, and then another earth for the casing.

 

What make of rev counter is it, and what to the connections look like?

 

Ant

[Guest TerryBarry]

The early Smiths electronic tachometers had a loop wire from the coil which went round a little plastic block. This was held in place by a metal clip - this formed the primary of an induction loop. The plastic block and metal clip were held in place by a knurled brass nut.

This was probably very early 60's

Enough history for today

Terry