09-03-2025, 09:45 AM
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...
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...