A Curious Conundrum.

With the ignition switched on, the indicators work perfectly. Add the lights – no snags. Switch on the fuel pump and the right hand indicators flash away merrily but the timing on the left indicators slows to zero and they stay on or off depending on which instant the indicator was applied. The fuel pump is obviously the culprit and I understand from my researches that they can generate considerable amounts of electrical noise, thus interfering with the electronics in a car. What makes the problem more curious is the fact that the wiring for both left and right indicator circuits runs past the fuel pump but the left indicator only is affected. I’m now reading up on ferrite core sleeves. In similar vein, the rev counter continues to indicate twice the revs the engine’s doing. It was from a Rover P5 – 6 cylinder, negative earth – so I would have thought it would work correctly. But it doesn’t and the addition of a ballast resistor was a complete red herring. The only good thing about the rev counter mis-reading is that about 3000rpm indicated, happens to coincide with roughly 30mph (the speedo’s reading double as well and needs a 2:1 reduction gearbox in the cable).

Inspection

A trip to my local garage for what amounted to an MOT, found everything in order except a bit of play in one of the track rod ends that I shall address. It was very nice to get under the car, have a good tug at a few bits and pieces and check for leaks around the engine. And, when we got home, I remembered that the Austin and the Hillman had never been formally introduced…

Specials 2

The Austin looks a bit naked without its wings…

Specials

And on reflection…

Reflection

The Hillman is still running very rich. At the local garage we once again put it on the exhaust gas analyser and the hydrocarbons were again very high. I’ve booked the car into Wilshers Garages’ rolling road but meanwhile I’m going to swop the standard needle for the weak one and see what happens. Weakening the mixture by screwing up the jet nut does help with the emissions but I can tell that the mixture’s too weak and that’s as bad as too rich – possibly worse. To eliminate all my shooting in the dark, the rolling road should be the answer.

Horn Bracket

A few small jobs that dot the ‘i’s and cross the ‘t’s continue to occupy me  – the horn trumpet bracket and re-torquing the cylinder head nuts. Whilst the cam cover was off, I checked and re-set the valve clearances, all of which were between 4 and 5 thou too tight. The Hispano valve adjustment is an absolute delight; it’s simplicity itself – one spanner to stop the valve from turning, a second spanner to wind the clearance in or out , 1 click either way equalling 1 thou. The worst bit of the job was turning the engine over with a box spanner and tommy bar on the crankshaft nut. There’s not a lot of room between the radiator and the front of the engine but, on the other hand, using a starting handle you wouldn’t be able to see the cam lobes because the radiator’s in the way, presenting something of a conundrum, what?

Advertisements

3 comments on “A Curious Conundrum.

  1. Sue Wilson says:

    Great to see the Austin lined up with the competition! Onwards and upwards, you’ll get there.

  2. Hi Nigel,
    Back from the Pays Basque.
    About “What makes the problem more curious is the fact that the wiring for both left and right indicator circuits runs past the fuel pump but the left indicator only is affected. I’m now reading up on ferrite core sleeves.” The left/right discrepancy is maybe that the wiring on the left is collecting more of the spikes generated by the pump. You can think of it (the wiring from the indicator lever to the lamps) as an antenna receiving radio waves generated by the coil of the pump. When you action the lever you effectively connect that antenna to the indicator electronics; hence troubles… Ferrite core sleeves right at the pump input could help, or not… A capacitor too between the pump input and the pump ground. Or both. Try to get some help in situ from somebody who knows his strawberries. It’s difficult to give advice from so far away!
    Good luck.

    • Clever chap! The capacitor and an iron core at the pump input is exactly what I’m going to try. Awkward put me on to it and I would have done it last week but I had to go an inspect an aeroplane at the last minute – as you do… Thanks Renaud, the bit about the antenna makes it very clear.

Leave a Reply

Fill in your details below or click an icon to log in:

WordPress.com Logo

You are commenting using your WordPress.com account. Log Out / Change )

Twitter picture

You are commenting using your Twitter account. Log Out / Change )

Facebook photo

You are commenting using your Facebook account. Log Out / Change )

Google+ photo

You are commenting using your Google+ account. Log Out / Change )

Connecting to %s