Rev counters

[neil parsons]

Gents

Rev counters

When the engine was running on points the aftermarket rev counter worked correctly. Having since fitted accu spark electronic ignition things have gone astray

• Aftermarket rev counter – the engine idles at 400 rpm and its all over at around 2700 rpm
• Cortina 1600e rev counter – the engine idles at 900 rpm but flies up to 7000 rpm. It looks good but the rate at which it gets to 7000 rpm is unreal. If it had a fully lightened and balanced engine with knife edged crank on farndon rods then maybe , just maybe. But its a boggo standard 1.6 cross flow.

Any one got some advice on how to wire up these rev counters , the aftermarket version had wires going to either side of the coil.

Neil

[neil parsons]

the rev counter has a spade terminal and a threaded post. I also have a white looped wire as you describe.

so spade is + and threaded post - , is the white  loop wire in line with negative side of the coil ??

[James Doulton]

Last week I finished my home made rev counter for my Rickman. It uses an Arduino micro-controller and it senses the connection from the coil to the points. When the points are closed the negative terminal of the coil is connected to the earth. When the points open then the negative terminal of the coil oscillates with a peak of 200V briefly, then dropping to 40V. My rev counter detects the 200V spike and measures the time between them. The display shows a bar graph and the actual figure. On the bottom row it shows the corresponding speed in the 5 gears (for my particular tyres and diff ratio).

I was going to make another more sexy version for the Dutton but I have also bought an Accuspark for it, so I might need to re-think the electronics if the Accuspark is different.

The reason for making my own was because the Ford one is pretty inaccurate (see picture) and because the speedo is way out too!