myoldjalopy wrote: ↑Thu Dec 04, 2025 9:55 am
Ah, I see! Thanks, Mike. I guess the answer to that was to remove the leads from the plugs, or just take the cap off......
Yes, that's one solution. But the module's instructions warn against running it with no load (ie the plugs).
Once I'd experienced it, there were other ways of avoiding this instant start; reverting to standard ignition (a 10 second job), or putting a bulb between the battery+ and the points, with the coil out of circuit. This also saved having the ignition on, and the petrol pumping.
Oh my! I think I'll stick with my standard points set-up! And to be fair, since using the Dizzy Doc's points, rotor arm and condensor (about 15 years now) I have had no ignition problems. All my faults/breakdowns have been mechanical - broken clutch linkage, broken crankshaft, worn-out steering rack, failed oil pressure switch, broken damper bolt etc. etc.
My ignition has been standard for over 12 years too.
There was one mystery breakdown about 5 years ago, that self-resolved with taps and wiggles.
And two years later there was a full breakdown, quickly diagnosed to a broken wire inside the (1000 mile old!) coil. Probably the cause of the first one too!
Ah well, you can't blame the points system for the coil breaking up....and a 1000 mile coil too! I'm guessing it was a modern replacement. The good old, proper job coils rarely fail, hence the old adage - it's never the coil!
Yes the "new" coil was a shiny, boxed one that come as a spare with my second Minor. So before the MOT to Duravel I diligently replaced the 20-40 year old one with the new one. Fortunately I'd kept the "old faithfull" in the boot.
The new one's autopsy:
Myrtles Man wrote: ↑Thu Dec 04, 2025 1:52 pm
As you obviously have a good understanding of such kit plus first-hand experience you may be interested in pulling apart an SX4000 to confirm/refute Autoshite's verdict; if so you can, for the cost of postage alone, have the one that I bought and briefly fitted to my Moggie, removing it soon after fitting as it made the car run worse!
My time time constraints lead me to offering first refusal to Neil
Some years ago, back when I was a student, I did build a very basic homebrew transistor electronic ignition. It was just a transistor as a switch driven by the points, nothing fancy, so no real improvement over the points, except perhaps less points erosion due to handling a much smaller current. It worked well enough, I took it off because I didn't want it failing whilst my parents were driving it.
myoldjalopy wrote: ↑Fri Dec 05, 2025 9:20 am
Yes, it doesn't pay to throw away a tatty looking reliable old coil for a shiny new one - 'all that glisters is not gold'!
Exactly. If it looks too shabby an old coil can be repainted. It's the internals that count.
Distributor Doctor recommends coils made by Pertronix. These are expensive and they need a new bracket as they are a larger diameter than standard coils. There are oil filled and resin filled versions. Resin filled is said to be highly vibration resistant and so better for mounting on the dynamo. Oil filled dissipates heat better so is better in high performance applications (e.g higher cylinder number, higher revving engines). I have one of these Pertronix resin filled coils and no trouble so far (4 years).
Stephen
1969 1098cc Convertible “Xavier” which I have owned since 1989.
Just in case I forget the figures, I've written on the side of all my coils the measured resistance of the primary and secondary. ISTR it's typically 3 and 10,000 ohms respectively. For this to be of any help in a breakdown, you obviously need to keep a multimeter in the car. But doesn't everybody??
Equally obviously (?), take the wires off the installed coil first; otherwise you'd be measuring other parts of the system (and perhaps getting damaging current into the meter's ohm range).
I had a modern coil fail in around 500 miles, when I took it appart the flexinle braiding between the coil and terminals had beed completley soldered so no flexibility. One of my cars (elan +2) has had Lumentaion for the 30 years I have had it and it was far from new then, its been faultless.
On the minor we went mad and fitted a fully mapped distributorless system, which drives really well.
Sparkrite SX500 &SX1000 6dec2025.jpg (2.27 MiB) Viewed 6910 times
I think these there sort of things that Mike1863 was referring to (originally!), popular "Sparkrite" products in their time.
The SX500 is, I believe, a simple transistor switch that reduces the current through the points that I bought in the early 1960s and ran for many years on different cars without trouble. I've not used it for decades but I hope to test it soon.
The SX1000 claims to be an "inductive discharge" device that I've picked up along the way. I understand they depend on an electrolytic capacitor that are prone to dry out and die and so it'll almost certainly have to be replaced. I'll give it a go, and if it has expired we'll have autopsy and do a capacitor transplant.
Morris Minor, the car of the future. One day they will all look like this!
MikeNash wrote: ↑Sun Dec 07, 2025 2:38 pm
I understand they depend on an electrolytic capacitor that are prone to dry out and die and so it'll almost certainly have to be replaced. I'll give it a go, and if it has expired we'll have autopsy and do a capacitor transplant.
Yes, Electrolytic Capacitors can be a PITA... especially ones that are in Power applications.
There was an equipment that I worked on in the mid 1980s where there were around 8 or 10 such capacitors used, each one about the diameter of a 2p coin and about 10mm thick. If one of them failed, the it could literally blow itself completely from the printed circuit board...
MikeNash wrote: ↑Sun Dec 07, 2025 2:38 pm
I understand they depend on an electrolytic capacitor that are prone to dry out and die and so it'll almost certainly have to be replaced. I'll give it a go, and if it has expired we'll have autopsy and do a capacitor transplant.
Yes, Electrolytic Capacitors can be a PITA... especially ones that are in Power applications.
There was an equipment that I worked on in the mid 1980s where there were around 8 or 10 such capacitors used, each one about the diameter of a 2p coin and about 10mm thick. If one of them failed, the it could literally blow itself completely from the printed circuit board...
Old Kenwood Mixers are notorious for blowing up capacitors on the speed control PCB. In fact I think the Germans call these particular capacitors "bangers". They can be replaced with modern capacitors that are more stable (as I have done with my mother's old mixer from the 1970's).
Stephen
1969 1098cc Convertible “Xavier” which I have owned since 1989.
