Awesome!

I FINALLY had some time to dive back into the distributor. 

Pretty sure the original problem was caused by worn out parts or loose connection. Then, when installed new points/condenser I accidentally had one of the wires badly positioned so it was grounding out. Removal and careful reinstallation solved it. 

Thanks for all the advice. One bright side is that I now know the correct procedure for troubleshooting whn there's no spark!

 

 

To test / confirm the grounding is done correctly:

Pull out the HT lead from the centre of the distributor cap and place it in a position that creates a small gap (say 5mm) to a metal part of the engine.

Next, remove the wire that connects to the side of the distributor (normally white with a black tracer) and "flash this to earth with the ignition on.

As you "flash" this wire on and off earth you should also get a spark at the ht lead.

Just for info "flashing" this wire to earth is the same action as that of the points etc in the distributor so if this technique gives you a spark then chances are that the points have been incorrectly installed in the distributor.

Here is a link to a thread that touches on the two most common grounding issues that almost all of us have had experience with, at least once:

//www2.mg-cars.org.uk/cgi-bin/gen5?runprog=mgbbs&mode=archiveth&archiveyear=97_2014.dat&access=71412491004047&subject=97&subjectar=97&source=T&thread=201406212237034927

Norm

If everything checks out, but still no spark, then re-check your points installation - perhaps they are grounded where they should be isolated.

Norm

It sounds stupid, but one time I mixed up the rotors between a 25d and a 45d and had the same problem. Check the gap inside the cap, it would be obvious.

Thanks everyone. I have spark from coil. No time to dig deeper tonight but I'll check rotor tmrw and update with more info about what days leading up to this little issue. 

The trouble with newer coils is that they mark them + and - which means you can't be sure which is the CB terminal and which the SW.

This matters - the primary and sec windings should be commoned at the CB terminal.  If the wrong way round you loose a signioficant amount of spark energy.

Re install the old condenser if you still have it there are a lot of new bad ones being sold along with the rotors. I installed two new ones in my 79 and they both went bad in a very short time the last one on a Mini drive out of town, i ended up replacing it on the side of the road with an old (looks 70's) condenser and it is still working fine 1.5 years later.

There's been a bad batch of rotors floating around for a couple of years now when they get a bit warm the carbon in the plastic that makes them black starts to short out, easiest path to ground then becomes the rotor to Dizzy spindle. easiest check is take off the coil wire from the cap and with the cap removed crank the engine (with Ignition ON) and hold the bare end of the coil wire about 1/4 inch from the top of the rotor if you see a spark It's a bad rotor

AJ,
You've been around here for a while. So, I'm going to assume that the car would run previously.
So, what did you change if anything?

instead of testing the spark plug wires, try your spark tester on the fat wire that  goes from the coil to the center of the distributor.

pull the end of that fat wire out of the distrbutor, attach your tester, and ground the end of the tester to metal, not the top of the distributor.

when you crank, if you now have spark at the tester, that tells you the coil, points, condensor are working and the problem is downstream, ie, either the fat wire, or the rotor, or the cap, or (unlikely)  all 4 plug wires.

 

 

Yes, i've replaced cap, points and condenser. Using a "spark tester" (wire with bulb that you plug in between wire amd spark plug).

The only other item I haven't replaced is the rotor (didn't have one). Rotor looks ok, but could that be the cause of no spark whatsoever?

Pretty sure I have the points gap set correctly  Is it possible to be so far off on timing or something that I won't get any spark?

 

The numbers you measured sound reasonable and coils seldom go bad.

How have you been checking for spark?  Have you set the points and replaced the condenser?

I have a Lucas sport coil connected to a Lucas 45d distributor with points and mechanical advance.

My trusty multimeter shows 12.6 volts feeding into the positive terminal.

Primary resistance is 3.2 ohms.

Secondary resistance is 9,400 ohms.

I'm pretty sure all those readings are within spec, but I'm still not seeing any spark.  Am I missing anything, or is it possible to have correct readings and still have a bad coil?