Rev Counter Dial

[PeterDraper]

I have been running my71 Sprint for the last 34 years so I am fairly at ease with it. The rev counter works fine some of the time but will fluctuate wildly at others. It has done this for some time now. I have changed to an alternator over the last 2.5 years, but from memory it was the same before the conversion. I am now wondering if I should cheque any wireing before sending the unit to speedy for repairs.
Peter

[Frank Howard]

Peter,

Did you upgrade to electronic ignition? If so, did the tach start acting up at that point in time?

[PeterDraper]

Thank you for your prompt reply Frank, in truth I do not rember when it started but at least three seasons ago. I did no mods to the Electronic ing system after installing the alt. I know it reads at least 500 high when steady.
Peter

[elansprint]

Peter if you electronic ignition fitted that will be the cause the tacho is current driven(RVI) and the current flow in what used to be the points cicuit is a lot less with electronic ignition & gives unreliable operation. You could convert tacho to voltage driven(RVC) i just put up with mine
Ian

[PeterDraper]

Thanks Ian that is just what I have been doing. I will think about an upgrade come the winter
Many thanks
Peter

[Frank Howard]

Peter,

Before you send it out for a conversion, think about this. Practically every car manufactured in the last 25 years came from the factory with electronic ignition. A good portion of them, probably half, have tachometers. Do you have access to a junk yard?

[ElliottN]

If it really is intermittent the problem may be ignition wiring.
I have electronic ignition (Alyson unit - in the car when I got it) and have suffered intermittent misbehaviour of the tacho from time to time. Aside from once being caused by coil failing and once by a cracked plug ceramic, I have always been able to rectify by thoroughly checking, cleaning and securely connecting all leads from/to the solenoid, coil, ignition switch, tach, distributor and plugs.