Under-reading rev counter - what can I do?

[V8Symphony]

My Chimaera 500 struggled to pass the MOT emissions test and the testers suggested the rev counter was under reading.

ON Saturday my unmodified car failed a noise test at Bedford because it recorded 103dB at '4000' RPM. My garage told me to check the rev counter by driving the car at 40 MPH in fourth, which should equate to 2,000 RPM - it does 1550 RPM on the clock.

The noise testers will test 'according to what they see' so trackdays will be impossible as long as this fault continues.

Can anyone help? The dial is in yellow to match the bodywork....it will be a nightmare to find an exact replacement.

Guy F.

Edited by V8Symphony on Thursday 22 August 06:22

[Discopotatoes]

Ring speedy cables

[TV8]

Not sure where you are in Surrey but you are welcome to pop around to mine and plug my rover Guage into the car and that will tell you what is going on, including accuracy of gauges. I am in Hayes near Bromley.

[QBee]

I am a little surprised it is that noisy, even at what must be 5300 rpm or thereabouts. Mine is only 101dB at 4500/4800 (I often over-rev it at noise tests - grrrr!), and it is fully decatted, which is much noisier than standard. IIRC it was only 96 at 4500 before I decatted.

Sorry you failed the noise test. I did notice that Bedford's meter read high when i was last there. FWIW Cadwell's was reading low last time I was there, if you are signed up for the TVRCC track day on 9th September.

Simple solution for TD purposes is to get some track day silencers from ACT. They are about £140 including VAT and P&P. They take about 6 decibels off mine and soften the sound, which the testers like, so I have not failed a noise test anywhere with them on.

If you want to try before you buy and live in Surrey, contact Phazed - he has a set of the ACT cans and is one of the most helpful guys on here. Download a free Iphone app called Decibel 10th, which I have found pretty accurate, and you will be able to test the noise levels

[V8Symphony]

Guys....thank you all for the help.....you've given me plenty of food for thought.....someone has also said that cleaning the connectors on the counter might help.....I'll let you know how I get on!