Technical Tips for the 346 and Star Page 5

Advice and guidance for the maintenance of Armstrong Siddeley cars. If you have other technical advice for Armstrong Siddeley owners you would like to share here, please contact sphinx@siddeley.org

Please note, technical tips are given by individual members and ASOC Ltd does not warranty the accuracy of them or endorse them in any way.

More tips can be found by using the links to the right.

Sapphire Reserve Fuel Pickup Wiring - Brian Watt

One reason many of these units fail is the rubberised insulation on the two wires breaks down and the wiring shorts out. It is not too difficult to repair.

To access the unit you may have to lower the front of the tank slightly. It is best to do this when the tank is empty as a full tank can be quite heavy. Once the car is on stands, remove the nuts holding the bracket on the front of the tank and loosen the nuts on the rear bolts. Remove the fuel pipe from the unit and unclip the two wires from their push-in connector in the loom.

The reserve tap is held in by two 2BA set screws. These had a screw head on my car but may be hex head so it pays to check. Be very careful removing these as if they snap off the tank has to be removed to drill the broken item out and rethread the tank. Gentle persuasion is definitely called for. I use a product called Reducteur H-72 to spray on rusted nuts and threads that are difficult to undo.
Remove the unit from the tank. Inspect for broken and damaged insulation on the wires, damaged or broken mesh screen on the bottom of the pipes and any cracks in the top of the pipes themselves. These pipes are subject to the weight of petrol sloshing backwards and forwards and some have been known to crack. If this occurs the pump will suck air not petrol. New pipes are available from the Stores if your pipes are damaged. The mesh is available and new material can be soldered on if damaged.

To repair the wires, the first step is to use a wide blade screwdriver to gently prise off the cap covering the coil. It is best to do this by twisting the blade in several places around the cap. Once it is removed slide the coil off and lay the coil and wires on the bench. There is no need to disturb the insulation material around the coil unless it is badly damaged.

Using a small sharp blade, slice the insulation on the two wires lengthwise. You can do this in short lengths rather than slice the whole length in one go. Break the insulation off with your fingers. It is generally quite crumbly once you start and comes apart fairly easily. The two wires are multi strand so be careful not to break the various strands as you work along the wires. Once all the insulation is off separate the wires particularly where they enter the coil. Slide a length of shrink wrap over each “wire” making sure you get them as close as possible to the points where wires enter the coil. This is a little difficult and I find you are best to separate the two wires carefully as this point using say a very small screwdriver and then put a small amount of mastic or silicone over the wires where they enter the coil so they cannot touch.

Heat the heat shrink using a heat gun and then to be doubly sure, put another length of larger diameter heat shrink over the two wires and shrink it.

Replace the coil and tap the cover on (I place a socket over the end of the cap and tap it on with this). Test the unit on a battery and if it is operating correctly, refit it into the tank. Smear the 2BA set screws with NEVERSEIZE or similar grease before fitting. This is a good practice for all bolts on our cars as it makes subsequent disassembly much easier.