Power to coil but no spark

Whats the car?

Id be running the multimeter through the LT system looking for voltage loss from bad connections.

Also have you tried a known good king lead?

Points, I take it? If so, they need cleaning - I too would expect 12V (points open) or 0v (points closed). Up to a volt or so with the points closed is probably acceptable.

We thought (and we obviously don't know a lot about electrickery) that yanking the king lead and shorting it would show a spark if there was energy in the coil OK but before it gets to the distributor thus removing points and condensor from the equation. Or do we suck big hairy balls with that reasoning?

Yup. Energy is stored as a magnetic field in the coil by the current that flows when the points are closed. When the points open, the current stops flowing, and that energy is released. Some of the energy heads towards the points, and causes a small spark there, while the rest heads towards the plugs and causes the big spark there.

When the points have only just opened the gap is very small, so the spark jumps easily. The condenser absorbs some of the initial energy from the coil, giving the points time to open further. This reduces the size of the spark at the points, which a) frees up more energy for the plugs and b) stops the points eroding as quickly.

A quick test of the LT circuit is to turn the engine so the points are closed, switch on the ignition, and flick the points open quickly with a(n insulated) screwdriver. You should see a spark at the points. It should be small and yellow. If it's big and blue, the condenser is at fault. If there's no spark there at all, there's no energy being stored in the coil - this is caused by no (or little) current flowing in the LT side - or no interruption in the current flow.

The normal cause no current flowing is corroded points (especially if the car's been stood for a while - the points often sit open with the engine off, leaving the surfaces free to oxidise). However, it could also be (in order): the feed to the coil (already confirmed good); the wire between the coil and the dizzy; the wire to the points moving contact; or the earth from the baseplate to the dizzy body. Measuring the voltage at various places with the ignition on and the points closed (as you've done already, but keep moving down the chain until you suddenly see zero volts).

No interruption in the current flow is cause by a short between the moving contact and the dizzy body - could be the flying lead from the points, or a bit of swarf across the points. However, as you've got volts between the coil and the dizzy, I don't think that is the fault here.

No, it was broken already.

Its been sat since 2001 so corroded points and so on are all entirely likely.

The red wreck, trying to get it running so it can be moved a bit. Seems like everything works so far except for it not starting. Once it runs I can check the trans and the brakes properly (although they seem OK on testing so far)

^unless the points are corroded allowing only a minimal current to flow when closed which is not enough to sufficiently charge the coil.

^ what was your degree in out of interest, I'm presuming from what you put it would be electrical science? As on my course Beng Automotive Engineering we didn't cover Faraday in any depth until midway through second year. In first year we had the typical explanation of "it does this you don't need to know why only that it does" then they explained it properly in second year.

What you've put is 100% as I remember the electrical science lecturer explaining it as so please don't think I'm trying to say your wrong as your not.

This is as you said one of the reasons why magnetic or Hall effect ignition gives a stronger spark. As a condensor is unessesary the current can drop quicker giving a higher voltage spike and a stronger spark. But if you tried running points ignition without a condensor to slow down this drop in voltage your points would rapidly burn out.

Yes and the condensor is there to suppress the spark across the points. So doing away with both and using an optical or magnetic pick up in their place along with a transistor gives a far better spark.