Series 3 Oil Pressure Gauge

[chris420sa]

I'm thinking of installing a mechanical oil pressure gauge on my 1972 Series 3. The current electrical gauge dial is 0 to 80 psi range which I assume is the originally fitted gauge?
Can a member please advise a supplier of the mechnical gauge together with adapter, tubing etc and having the same 0 to 80 psi range?
Many thanks
Chris

[71 V12]

When I converted to mechanical gauge I removed the face dial from the original electrical gauge and fitted to the new mechanical gauge. Looks perfect and works great.

[ReconPilot]

71 V12,

Easy enough to do, swapping face plates but any idea what the wet gauge calibration is? To my thinking the gauge now just tells you whether or not you have oil pressure - correct? Readings: No pressure, a little pressure, higher pressure and real high pressure. Please let us know what you did to calibrate the gauge to the new face plate.

Cheers,
Dick

[lowact]

Good luck,
The electrical gauge has a 0 – 80 psi scale and a 0-100 psi range (sender).
Note the elec. gauge scale is not linear, i.e. between 40 – 80 psi is smaller than between 0 – 40 psi. The mechanical gauge scale will be linear. To not lose accuracy you would want the scale as per the mechanical gauge with numbers stopping at 80. Any instrument technician could do this for you. Steps would be:

Select an appropriate mechanical gauge, 100 psi, ¼ sweep, with similar white needle and with the face plate depth the same depth behind the glass as yr Smiths elec. gauge. You will not be able to reuse yr Smiths needle because the Smiths needle pivots on a fulcrum, not on a pin:


Reprint the Smiths face to have the same linear scale as the mechanical gauge, stopping at 80. E.g here are original and reprinted faces, albeit for different purpose ... this pic is mainly to give u heads up of what a Smiths face actually looks like:


Note the reprinted text and lines are not as fine as the original, you get what u pay for.

Assemble the gauge using the mechanical mechanism with the reprinted Smiths face and the bezel; how difficult this will be will depend on yr original mechanical gauge selection. Again depending on yr mech. gauge donor, the mechanism may have to be upside down as required for the needle to sweep between the 8 o’clock to 4 o’clock positions. Doesn't matter.

Alternatively, I note that, after many years, the correct type of electrical gauge sender is now once more available, meaning that our electrical gauges may once more be accurate (enough). Without going into detail (ref other posts), the correct type have a double lug electrical terminal at top centre.
The incorrect type, that will be bizarrely inaccurate and short lived, have a single lug electrical terminal at top edge.