RV1 and RVC Tachometers

SydneyRoverP6B

SydneyRoverP6B

Well-Known Member
Staff member
According to the 3500/3500S Parts Book, there were two tachometers with different part numbers fitted. The first type, although it doesn't specify whether that was an RV1 or RVC, was fitted to all Rovers up to and including suffux D, and for the 3500S, suffux C. The second type was fitted to all Rovers from suffix E onwards, and for the 3500S, suffix D onwards.

Now comes the curiosity, my Rover which is a suffix D has an RVC type fitted, and that is the original factory issue. Warren's Brown Rover has an RV1 type fitted, which if I am reading correctly, should have left the factory with an RVC type.

So what is the intrinsic difference between the two tachometers? Can one or both be used with ignition systems where the ballast resistor has been bypassed?

Ron.
 
SydneyRoverP6B said:
According to the 3500/3500S Parts Book, there were two tachometers with different part numbers fitted. The first type, although it doesn't specify whether that was an RV1 or RVC, was fitted to all Rovers up to and including suffux D, and for the 3500S, suffux C. The second type was fitted to all Rovers from suffix E onwards, and for the 3500S, suffix D onwards.

Now comes the curiosity, my Rover which is a suffix D has an RVC type fitted, and that is the original factory issue. Warren's Brown Rover has an RV1 type fitted, which if I am reading correctly, should have left the factory with an RVC type.

So what is the intrinsic difference between the two tachometers? Can one or both be used with ignition systems where the ballast resistor has been bypassed?

Ron.
Click to expand...
RVI Tachometers work by sensing the current used by the ignition coil, whereas RVC Tachometers work by sensing the Voltage changes at the coil -ve/points connection. I am currently in the throws of adding electronic ignition to mine, and removing said ballast resistor for a new coil as well, and contemplating whether or not I need to modify my RVI tacho :? :? :?

I have read quite lot of information out there, regarding others that have had issues after installing various electronic ignitions, with results like unstable tacho's to others that won't work at all and some that install without issue. Nothing is ever simple is it :shock:
 
Hi Phil,

Yes things are never simple. Indeed looking into it further, it seems so far that my Rover should have been fitted with an RVI and not an RVC type, or maybe it is not at simple as that either. :?

I have been running a Lumenition electronic ignition system on my Rover for over 20 years, and have never had problems with my tacho.

Ron.
 
SydneyRoverP6B said:
I have been running a Lumenition electronic ignition system on my Rover for over 20 years, and have never had problems with my tacho.

Ron.
Click to expand...
It seems problems only arise if fitting certain electronic ignitions to a vehicle with an RVI tacho, so it seems that your RVC has saved you any issues.

The 'I' in RVI apparently stands for impulse, but I've yet to find out what the 'C' in RVC means :?, although it's bound to be obvious once I find out. Anybody :?:
 
codekiddie wrote,...
The 'I' in RVI apparently stands for impulse, but I've yet to find out what the 'C' in RVC means
Click to expand...

Hi Phil,

'C' for Continuous possibly? An impulse is a discrete measure whereas voltage changes at the coil would be continuous (ie analogue).

Ron.
 
SydneyRoverP6B said:
codekiddie wrote,...
The 'I' in RVI apparently stands for impulse, but I've yet to find out what the 'C' in RVC means
Click to expand...

Hi Phil,

'C' for Continuous possibly? An impulse is a discrete measure whereas voltage changes at the coil would be continuous (ie analogue).

Ron.
Click to expand...
Found only one mention of what it stands for so far, and that was..........

.....(C)ontact breaker, as that is where it is hooked up to :)

As I said before, so simple it's probably the correct meaning :roll:
 
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