Identifying an SU Pump??

[geoberni]

I have no idea which pump model I have, other than it being an SU with a Hump Top Pump Cap, Black with air vent hole. Which is a bit unusual, as both the AUA25 and AUA66 are supposed to be flat top, with no air hole....

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Some time ago it must've been overhauled and the little ID place lost when reassembled.
It's painted all over grey, possibly a Hamerite finish, apart from the cap.
It also has this little stubby fitting on the casing, adjacent to the Filter fitting, which I've not seen on other SU pumps
Another 'air hole' perhaps??

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Anyone recognise the model??

[svenedin]

The caps are interchangeable so it may not be the original cap. I believe the hump type was introduced when a capacitor was placed across the points (later a diode, now a Zener diode) to reduce arcing and radio interference. This was not considered necessary until car radios became common. I’ve never seen that little tube on the body of the pump but there is an air vent hole normally (just not a tube). It must be to equalise the pressure behind the diaphragm.

Here's as very elderly AUA66 of mine (I can tell it's very old because the coil wires are both black).

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[chrischris59]

This pump is fitted on my mgb and the barb is for an air vent most of the upper parts are interchangeable. I've used parts off an mg pump to repair the one on the minor.