Volvo 1800 (all) Smiths Tachometer Upgrades - Part II


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So what can be done about all the problems with the Smiths Tachs ?

We at offer a very unique and specialized product and service for modernizing all three generations of Smiths tachs for the 1800. We can also do these upgrades on similar era Smiths tachs from many makes of British cars such as MGs and Triumphs.


What we do is bypass the tired and obsolete circuitry in the 1800 tachs completely by disconnecting the wires from the instrument mechanism itself and wiring them to a brand new circuit board which is placed inside the tachometer so the gauge still looks completely stock from the outside. The old circuitry is left in place so the modification is 100% reversible if ever the owner wants it put back to stock. (It's doubtful that'd ever happen but it can be done if ever that situation were to arise.) In the case of the first generation P1800/1800S tach, the circuit board can either be placed inside the tach itself or placed inside an external box and placed where the original pickup/sender unit is located up near the radiator.

What are the advantages of this new circuit board you put inside the 1800
tachs ?

There are two main advantages to using this new circuit board.

Advantage 1:

The new circuitry is far more accurate than the tired old obsolete circuitry. This will eliminate as much error due to the electronics as possible once the tach has been properly calibrated leaving only error due to inherent mechanical/balancing issues coming from the mechanism itself. Those too can be minimized by proper calibration techniques.

Advantage 2:

The original circuitry only enables the 1800 tachs to be run in current sensing mode. Current sensing tachs haven't been made since 1973 and therefore most third party breakerless ignition systems cannot be used with any generation of 1800 tach. The new circuitry will enable the tachometer to be run in either current OR voltage sensing mode. This means that once we've made this modification for you, you will have a far greater choice of third party ignition systems that you can use in your 1800. Just about any system that's compatible with voltage sensing tachs (which is most of them) can be used. Without this mod, you're pretty much limited to using the stock (points and condenser) setup or the Perlux (Pertronix) or Crane XR3000 breakerless ignition systems.

Is this proven or experimental technology ?

Proven. These circuit boards have been used in hundreds of other cars that use similar design Smiths tachometers and have been proved to be both accurate and reliable. These circuit boards will work with the following ignition systems:

  • Stock Points and Condenser system
  • Points Amplifier Systems (Pertronix, Unilite, Mallory, Allison, etc.)
  • Voltage Trigger Systems, including Multi-spark Computerized Controller Systems (MSD, Jacobs, etc.)

Can the tach be calibrated to maximize accuracy once this modification has been made ?

Yes, we will calibrate the tach to a calibration standard but provision is made so that you can adjust the calibration if you feel there's a discrepancy between the speed you're travelling and the rpms shown on your tach. We highly recommend calibrating the tach at 4000 rpm to maximize accuracy.

Tach Rebuild Service

The tach rebuild consists of:

  • Disassembly and mild cleaning of the inside of the tach;
  • Check of meter movement and current sensor coils;
  • Installation of the circuit board;
  • Drill two holes in the back of the case for the voltage trigger wire and calibration access (optional)
  • Reassembly, calibration, and testing.

Please observe the following precautions when shipping your tach to us:

  1. Tape off any holes on the back of the tach case (i.e. the light hole).
  2. Enclose the tach in a ziplock baggie or similar air-tight bag.
  3. Use foam, packing peanuts, or bubble wrap to COMPLETELY fill the box you're shipping it in. If the tach can't rattle around in there it stands a much better chance of survival.
  4. We are located in Canada. Customs regards anything that comes across the border as something that we've bought, and therefore they reason that we ought to pay GST (6%) of whatever the value of that thing is before we get it in our hands, unless there's clear evidence that we didn't buy it. So by all means, insure your tach for whatever you think it's worth, but label the contents as being "used antique car tachometer", and that the value is "for customs only, no commercial value". The Harmonized Tariff Code is 9029.20.40.80, near as we can figure, or you can try to find a better match in the official doc at:
  5. You can figure out what the return shipment cost will be by choosing your method (Canada Post, UPS, or another courier service), hitting up their website, and finding their rate calculator.

What does it cost ?

Second Generation (1965 - 1969) tachometer (RVI 3410/00) upgrade: $190.00 USD*

Third Generation (1970 - 1973) tachometer (RVI 3412/00) upgrade: N/A - This service is still under development. Please contact us if you'd like to volunteer to be a Beta tester for us.

First Generation (1961 - 1964) tachometer (RVI 1310/00) upgrade: N/A - we're still doing some research on these. Please contact us if you'd like to volunteer to be a Beta tester for us.

* Installing this mod on a second generation (1965 - 69) tach requires R&Ring the chrome bezel from the tachometer which adds at least an hour of labor time to the job versus the 1970 - 73 tachometer. This is why it costs more to install this mod on the second generation Smiths tach.

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