Coverting points to electronic and looking after dizzys.

[History]

Distributors are called dizzys because it spins and gets dizzy.

It seems as a matter of course to fit electronic ignition to old cars.
The sellers of the kits claim better starting betting running better mpg more power and more reliable.

I have found that the claims to be not quite true.
My car has points it starts from cold with a 5 second burst from the starter motor in 26 years of ownership it has never failed to proceed as Rolls-Royce say. Thats reliable enough for me.

Once warm the engine is seriously smooth and loads of power. The generator light is the only indication that the engine is running.

MPG is 11 mpg and 18mpg cruising on LPG.
Rolls Royce used to test engines on LPG because petrol washes oil from bores when cold. LPG needs no choke to start. I don't use any petrol.

max speed 118mph at 4500 rpm. O to 60mph 10 secs.
Bearing in mind that 70mph is max speed and 10 secs to 60 is not slow.

Fitting electronic ignition is of no use.

Plus points can repaired with a screw driver and I usually know whats wrong within 5 mins of checking. Electronic ignition does go wrong and when it does it resists fault finding and more than screw driver will be needed.

Looking after dizzys.

They are simple Machines.
First step fit and gap new points. Oil under the rotor arm and squirt engine oil under the base plate over the weights on the centrifugal advance. There is usually a small drain hole in the dizzy body so the oil will drip out, so too much oil won't hurt.

A 4 cylinder engine fires every 180 degrees (angle).
Opposite TDC mark on pulley make another mark.

Start engine run at 1000rpm set timing to TDC. Then check no 4 cylinder which should be the same as no 1. 2 and 3 should be the same but opposite TDC on the mark made.

They should all line up. If they do the dizzy is not worn and fit for service. Allow + or - 3 degrees max. This is called timing scatter.

The centrifugal advance.
The weights don't wear and don't change weight. Lack of oil can cause the pins to wear but providing the wear is slight it will be OK. The springs are often different from each other and last well but are not expensive so fit new ones and forget for 30 years.
The centfrigual advance senses rpm only it cannot sense engine load. This means that the makers specification is an educated guess because the designer doesn't know how the car is going to be driven.

My Shadow has no vacuum advance.
The vac advance does sense load. At idle an engine has about 21 inhg. This pulls the vac fully advanced as the throttle is opened the engine vac goes down and the vac module retards the ignition so that the engine can accelarate without pinking.
To check simply suck and if the base plate moves and holds until vac is released, then the module is good to go.

The rate is controlled by a spring. This spring does not move a lot and doesnt get particularly hot so last well. Oil again is good.

The function of the condenser.
Most professional mechanics and nearly all diyers get in to a tangle on this.

The ignition coil primary windings have resistance. The condenser is a capacitor. The values of the resistance and capacity form a capacitor resistor tuned circuit.

When the points open the primary discharges and charges the cap. The cap then discharges back though the primary windings. This happens 5 times. It is called ringing and because of 5 times tau 5. This appears on an oscilloscope as a 12kv spike then 5 small spikes at about 500 volts and fadding. At the spark plug the 12kv starts an arc which allows the condenser to maintain for 5 spikes at a lower voltage. In electronic circles they call this the RC time constant.

The spark plug starts the fire it does not add power.

Modern engines are designed to take advantage of electronic ignition. If a modern engine were to have its coil packs replaced eith a points dizzy then it would probably run not very well.

Old cars that have points were not designed to take advantage of whizz bang modern ignition.

Timing the spark.
My method is to warm engine. Set idle to 1000rpm. Advance dizzy till engine runs rough then retard till smooth plus 1/2 a degree for luck.

Drive a mph in a high gear and floor the gas. Any pinking retard 1/2 degree.. if no pinking advanve until it does then retard.

when refitting dizzys set engine tdc with no 4 on valves rocking.. turn dizzy so the points are fully open. This should give a bit of advance to start the engine. If the engine kicks then retard.

[Toledo Man]

Electronic ignition is not affected by timing scatter unless the dizzy shaft is seriously worn. It is generally more reliable than points and condenser and is virtually maintenance free. There are plenty of poor quality ignition components (points, condensers and rotor arms) so it is no wonder that plenty are converting to electronic ignition.

[kevin]

My Singer had been converted years ago to a Lucas electronic set-up, the fact that it was slowly breaking down caused no end of running issues as it always gave a good spark in the garage!.
Luckily it gave up totally on the drive. The quick solution was to try the accuspark set up which was fitted in minutes and to be fair, for £58 delivered for the complete distributor, gives superb results.
A bit of luck got me a brand new, old stock, conventional distributor which is on the shelf awaiting fitting.

To be honest, I think the items from accuspark and co offer a good solution where the original distributor is beyond economic repair.

Kev

[History]

Electronic ignition can indeed make timing scatter less. It wont cure it entirely but due to the absence of the side load of the points the rotor will run truer if the brgs are worn.

I am aware of bad quality points etc. I use genuine lucas stuff on my Shadow the points last for years.

Incidently the condenser is quiet reliable.

If a points system is working well then I don't fix what isn't broke.

Key thing is to keep dizzys well oiled and they will do many miles with out trouble.

My first car was a 100e ford esquire estate car 1172 cc side vavle. I drove that car for 10,000 miles with no points adjustment. That's quite reliable to me.

The point I trying to make is that in cases where points are working fine the gains in fitting electronic is not a lot.

Pun intended.

Note I was expertly informed that the points ignition on my Shadow was inaquate for lpg and I need a sports coil electronic ignition and special plug leads. My car runs fine on lpg on the 41 year old standard ignition system.

Regards
Bob Reddington.

[JPB]

Edited as I don't really wish to be sued by the purveyors of what passes for quality ignition spares these days - the chiselling badstarts!

I've had both good and bad experiences with electronic ignition. An expensive Lumenition Optronic system failed once in one of my most competitive autotest kittens. I always carried a spare distributor, ready to fit with its points set to the correct gap and its own clamp so that it simply had to be popped into the hole and matched up with the marks I'd made for the purpose.
A slightly cheaper Pertronix Ignitor system failed in a Rebel, that car also carried a spare, ready to go, stock distributor in its luggage compartment.
A standard, factory issue Lucas electronic distributor in my '88 Metro died in the middle of nowhere during a blizzard and I had no such spare conventional distributor.
My Morris Oxford, 4388DG, never had electronic ignition fitted but that was fine because its contacts seemed to last between services without any fiddling, this I put down to my habit of NOT oiling the sponge that lubricated the heel, which meant that the heel wore at a slower or similar rate to the contacts themselves and kept the gap satisfactory throughout the life of that set of contacts and no, 25Ds didn't usually have that sponge, it was more a late 45D thing, but I fitted one in a DIY forky thing just so that I could then not use it.

[History]

My jeep is electronic and the coil went £46. The Shadow coil is £15 and is 41 years old.
As I said electornic ignition does go wrong. Road side repairs are easy and possible with points whreas electronic hard and usually not possible at road side. Been there done that.

The choice to convert is up to the owner I am just pointing out the pitfalls that waste time and money. Simply points do work and advantages of electronic are over stated.

However there is a new kid on the block. There are dizzy which have a programable electronic advance. They are also bi directional so one model fits lots of cars. They come on 4 6 and 8 cylinder version. Fine control over advance is very useful and set right can give more power and better mpg. The mechanical advance just cannot fine control advance.

Carb and dizzy is like a mechanical engine management system that works better than one might think. A Minor is about 26% effefficient modern cars at a guess 29%.

Bob Reddington.