Keeping it original.

[Ray White]

Thanks Tony. I certainly don't have any 5BA hex head screws!


I shall order some today.

[Ray White]

Here we go again!..........or NOT as the case may be!!!

No spark.  I checked the condenser by substitution and thought I had solved the problem as I got a spark from the king lead against a head stud when I flicked the points ...but I hadn't noticed that I was opening the points to far and earthing against the body of the distributor; this produced a spark from the king lead  which I mistakenly thought was HT .....but it couldn't have been.  

When I opened the points more sensibly I didn't get a spark.  I guess it is evidence of a defective HT coil winding? ...unless I have two duff condensers?. Even so, I would have expected to get a spark of some sort.

I checked the rotor arm and there is no spark there so I presume that it is O.K.  There is no evidence that the distributor cap is cracked or has been arcing and the HT connections are sound and free from corrosion. There are no frayed wires and I have cleaned the points with fine sandpaper.

I am getting the correct primary coil resistance  - 1.4 ohms  (same as always ) and when I tested a wire from the CB terminal on the coil with the points open I witnessed full battery voltage, so again the primary circuit seems O.K. 


With the points closed I believe the reading should be zero volts; however, I am still getting full battery voltage which sort of implies that the points are dirty...but  I have cleaned the points. Perhaps I need to do even more cleaning.? The cam is definitely opening the points...

Here's the strange bit.  I half expected the coil to be the problem as it is possibly original to the car ...but when I tried a brand new coil I still get no spark.  Not a glimmer of one.  

Surely I must be going wrong somewhere?  ...or could it be the new coil is faulty.? Just to be sure, I removed the CB wire and the king lead from the distributor and then tested them to earth. By occasionally glancing the CB wire to earth I had expected a good coil to produce a spark from the king lead to earth . The result was nothing from either coil. (and yes, the ignition was switched on!)

Any ideas?

[A G Wood]

With the points closed, however, I am still getting full battery voltage which sort of implies that the points are dirty.  I have cleaned the points with fine sand paper as usual but it makes no difference.  Perhaps I need to do even more cleaning.?

Whats the earth path on those distributors Ray?
 Not familiar with the CAV unit, but if it has a Bakelite action plate, like the contemporary Lucas ones, is there a link buried in the bakelite which connects the fixed (non-coil) point to the metal of distributor body somewhere (Lucas use one of the action plate securing screws and a tiny copper washer to do this) that may be open. Also make sure the distributor is earthed to the block (and by extension the grounded battery terminal). 
Later distributors use a flexible (and visible) wire to do this ofc.
If you do decide to check the distributor ground circuit, I suggest using a test light between the battery live and the fixed point, you do need to load the circuit to approximate coil primary current, which in your case is I=V/R: 6/1.4 = ~4.2A, so you would use W=VA: 6 x 4.2 = 24W globe. Checked with the points open.

I don't have an answer for why you don't get any HT action touching the CB wire to earth, other than to suggest checking continuity (you should have something in the 6-12K ohms range) from the HT terminal in the coil tower to (either) primary terminal to make sure you dont have an open circuit. Also maybe check for short circuit between the HT terminal to the coil can while youre there.
 If it's a conventional coil you should have continuity to both-one has the primary circuit in series and one doesn't. But, and a big but, once again I am not familiar with CAV idiosyncracies,  if electrical system is of a certain age it may be necessary for the coil can to be earthed (some of this era US product uses this system, as did insulated return vehicles).

Also any capacitor in the 0.22 microfarad/ 450v range with clip leads will do for testing purposes. Connect it at the CB terminal on the coil (disconnect the OE one first)

Apologies if you know all this already...

[Ray White]

I checked the primary coil circuit for resistance with the meter (set at 200) and got 1.4 but when I checked the HT (set at 20K) I only got 2.7

I guess from this I must have a faulty coil.?

My (spare) coil (set at 200) reads 1.7. Ohms primary and 7.3, KOhms secondary (set at 20K) which I guess is O.K.?