Rover P5B saloon - correct ign switch for anti theft coil

[ricky8664]

Obtained the electronic distributer and coil but have been unable to get the car to run. Even succeeded in exploding the front silencer, probably due to too much retardation. But that's another issue

However, we seem to be having problems with an intermittent live supply from the ignition switch to the coil. Happened 8 months ago when we tried to start the engine for the first time in a dozen or so years. Ran a direct live from the battery to coil and it fired up. But the next day was working fine from the ignition switch.

However, with the newly fitted electronic distributor we've been having problems again with the live. We are going to run a live direct from the battery again but I'm looking to fit a new ignition switch oif the live feed proves to be the problem.

Problem is my car originally had the anti theft coil with armoured cable. The coil was replaced years ago and I just cut through the armour at the coil and never touched the ignition switch end of the armoured cable.

JRW lists 2 ignition switches. One mounted on the dashboard and one mounted on the "console". No idea what that is. Mine is mounted on the Left hand side of the steering column shroud. Is that the "console"?

I've just written to JRW but have not received a reply (it was only 10 mins ago so not criticising), but thought it worth finding out from here would be likely to identify how many different types of ignition switch there are and which one will fit may car. Do I have to replace the barrel too, into which the key fits?

[enigmas]

Earlier model P5Bs had the ignition key fitted to the lower right hand corner on the instrument binnacle on RHD cars.

I believe later P5Bs had the ignition switch relocated to the left hand side of the the steering column surround.

[lagain]

When you turn the key do the red and green lights on the binnacle go out.
If so you are losing the power, and it will not start. A points set up does not need the power that an electronic system does.
With the armoured coil it is not possible to get to the contact and you may need an external power source.
Strangely some times it will start, but on mine, which still has an armoured coil, I took a lead from a constant power source, which, from memory was the interior lights !
I have an identical switch to the windscreen washer, which is fitted on the other side of the binnacle.
When I took the lead from the interior lights I did not have the knowledge of power draw that I have now, but I don't think that it draws very much.
I also think that I had to have something done to the rev counter, but it was 1979 !

I am only talking about the system on my car and yours may be different.
I am writing this on a tablet which I find difficult, so it may not be as clear as it should be.

[ricky8664]

Think I'm a bit confused after the last reply, particularly the bit that said the power comes from one of the 2 coil connections. Though I may have misunderstood.

On the old points system, the lead that came from the ignition switch (inside the armoured cable) connected to the + terminal of the coil. That is what supplied the power to the coil. THe - (minus) terminal on the coil went into the dizzy and connected to the points/condenser, with the base plate being earthed to make the circuit. Each time the points opened this broke the circuit causing the high voltage part of the coil to generate and discharge its spark via the HT lead to the centre of the Dizzy cap and to distribute  the spark.

With the new electronic dizzy there are three connections on the module outside the dizzy. It came with a connector (a 3 wire to 2 wire connector). The 3 wire bit connects to the dizzy and the 2 wires left, attach to the coil, one to the positive and one the negative. So the new set up leaves the coil with 3 wires attached rather than just 2 with the old points. I don't know how the electronic part works and therefore why there are 3 (LT) connections from the dizzy. But I don't believe I need to know how it works for these purposes.

No spark is being generated as neither my old timing light nor my mechanic's new one would flash at all when connected to the No.1 spark plug lead and the engine was cranked. Whilst it could be a faulty new dizzy or electronic module, it seems most likely at the moment that the system is not getting any power thru the Ign switch, which is where we will resume on Friday (by running a direct live from the battery to the + coil connection to see if that livens things up).

BTW we have fitted the new coil that came with the  electronic dizzy and new dizzy cap and leads, so the fault may lie in one of those, but the plan is to start at the supply of voltage to the coil, and go from there. 

My question was really about what type of Ign switch should I get to replace mine, if it proves the live feed to the dizzy is faulty/intermittent.

[lagain]

Jan 11, 2024 21:13:14 GMT enigmas said:

Earlier model P5Bs had the ignition key fitted to the lower right hand corner on the instrument binnacle on RHD cars.

I believe later P5Bs had the ignition switch relocated to the left hand side of the the steering column surround.

I have adjusted my previous post.

You may need professional help in setting up your electronic distributor. Hometune and Tuneup are usually quite good as the mechanics tend to be older and they have lots of equipment to get it right.

There are only 2 possibilities for the ignition switch

[ricky8664]

Cannot get the engine to run at all with the new electronic dizzy coil and leads.

My mechanic and I have spent 6 hours fitting the new dizzy and trying to get the car to start.. Doesn’t even sound as if it wants to fire apart from one almighty backfire that literally exploded the front silencer.


Checked that the dizzy is in the correct place by No 1 cylinder & there is petrol getting to the engine.


We are getting one thing that does not seem right. With the ignition switched on we are getting 12 volts at the + terminal on the coil (from the ignition switch). However we are not getting 12v across the coil (i.e. between the + and – terminals. Only getting 0.8v there.


However, we are getting 12 v between the + terminal on the coil and the output (HT) from the coil. And this is just with the ignition on, not cranking. Seems like a short within the coil.

Fuel is being delivered BTW. It would not even start with go juice squirted into the carbs, which is how we got it to fire up when first starting the engine last spring. Absolutely dead.




Having taken everything apart twice and re-connected , we took all the spark plugs out and then tested them in their respective plug leads against a good earth. 


All of them were producing a very good strong regular spark. However, in between the strong regular sparks, each plug was also producing repeated small sparks at the electrode several times between each big spark. I have never experienced that before.


Next time we will be substituting a good coil. But I also think it may be the new electronic dizzy that is faulty.


BTW we have also checked the compressions. Whilst a couple were down at 130psi, most were between 160 and 180 psi, below the stated 180 to 190 psi on a good engine, but still not so low as to prevent a start.


And as I said, it has turned over without even trying to fire or sound like it wanted to run apart from the exploding silencer incident.

I have written to the supplier with the problem but have not yet heard back.

Any suggestions?