Morris Minor Owners Club

Hi there. im having problems with my dizzy at the moment. Its squeeking like hell once the engine warms up a bit. I have oiled it at regular intervals and it has been known to give a squeek after a long motorway run, but now its constant, ive reoiled it with engine oil and WD40 with no change.
Also whilst changing the ignition timing by turning the dizzy with its clamp loose and the engine turning, i keep on get an electric shock from the top of the dizzy cap. Is this a sign of voltage leakage and new leads required?

Hello M,

unusual, where have you oiled?
I would remove the unit and see if it is dry where the dog meets the body. I'd expect engine oil to splash there and lubricate it. Better still, drive the pin out and remove the dog (make a clear note of how the dog orientates to the spindle else you can fit it 180 degrees out and upset your timing) and check if it is dry.
Any sign of the rotor arm contacting the cap at all?
Yes, the shock is leakage and could just be dampness, no real problem if the car runs OK.

Alec

...but not a good idea to keep touching it, there's lots of amps flying about down there, and it doesn't take many to stop your heart

There's barely any amps at all...

The 20,000+ volts is more likely to cause a tingle though ;)

In that case, I take it back - 20,000 volts is about the same as a static shock, it's the amps that would kill you.

Aye - high volts and very low amps - wakens you up though ! Best to stop the engine - then turn the dizzy - then restart. To be honest - I advance in lumps till the engine kicks against the starter, then take it back till I can get it started - then road test with further advancing until I get some pinking - then back off slightly till just the lightest of 'tinkles' when flooring the throttle. Without a dynamometer it's about the best way I know.

I have oiled the central spindle and the side of the cam and for good measure a little bit lower into the dizzy bowl. Can anyone confirm which dizzy should be fitted to a 1098 1971 saloon high compression engine. At the moment its a 25D4 but looking through some of my technical data it might be a 45D? What is the difference between the two?

One of the ways to test for a good spark seems to be to get someone (usually me) to remove a plug lead, then before the someone (ie me) has had chance to get a pair of pliers to hold it, turn the engine over. That one's about as funny as sounding the horn with someone's (me once again) head under the bonnet directly below the pointy latch thing

25d dizzies have a knurled nut on one end of the vacuum advance assembly, 45s don't. Also 25s have a rounder shouldered cap, and the condensor (under the cap, capacitor with a lead) wire is held in place by a small nut, rather than a push fit terminal.

There's also a difference between the points, but I can't remember one from the other off the top of my head.

Oh, and as to what should be fitted, I don't know - But my 72 and 74 cars have 25d's, as does every Minor engine I keep falling over. Well, other than the one I put a 45d on as it was there and we had a good cap for it (was easier to fit another dizzy than pop down the road to buy a new cap)

A good way of remembering the volt/amp thing----------
Volts give you the jolts, Amps put out your lamps!

Generally the 1098s have the 25D4 and the 1275s have the 45D4

Hello all,

"Volts give you the jolts, Amps put out your lamps!",

don't believe it, voltage is a killer, as long as there is a large enough capacity that is what lets the amps flow. There have been rare cases of lethal shocks with double figure voltages. Industrial power tools use a 55volt to earth system which is generally considered safe.

Alec

That's true. And think about having 20,000v rapidly firing across your chest, and what's also in your chest.

However, in general a car ignition system isn't going to do for you, but I'm sure under certain circumstances it can

I don't like it when it happens simply because it flippin hurts!

Alec, in that case, expain how when you put your hands on a van de graff generator producing about 250,000 volts you dont get killed, however if you short out the 240v mains supply....

its the amps that kill you!

Matt wrote:Alec, in that case, expain how when you put your hands on a van de graff generator producing about 250,000 volts you dont get killed, however if you short out the 240v mains supply....

its the amps that kill you!

Well, it's all to do with the potential difference across you coupled with your impedance across the path.

So, when you are standing on an insulating block and touching the VDG generator you have virtually no PD across you as you have a very high impedance to ground thanks to the insulating block. Of course the moment you touch the earth you get a shock, but it does not kill you as you have disconnected from the source! The VDG generator also can't produce much power and the only reason the voltage gets so high is that it's output is floating. If you connect it to any 'load' then it won't produce much voltage at all.

When you connect yourself acrosss the mains, it has PLENTY of power behind it so can maintain the voltage when you are drawing current through your internal impedance. It's REALLY not recommended, but GENERALLY for healthy individuals, mains won't kill you. If it did I'd not be sat here typing this (many times over!). In fact at one point I got totally reckless and used to test if a wire was live by quickly tapping it with my finger! I stopped that though when I got a direct to earth mains shock from one arm to another with damp hands and it felt like someone hitting me at the back of the neck with a piece of wood!! Since then I've had a bit more respect for the 'ol elastic-trickery.