ballast resister

[Deleted]

Hi, does anyone know where the ballast resister (separate, not aniti-their lock) is located in my 1970 P5B, and how I can get to it for replacements?

Dennis.

[Phil Nottingham]

Yout 1970 model has the ballast resister wire in the loom - its PINK and increase in resistance as it heats up (slightly) . They are not required with these engines anyway and were dispensed with on the ballsst from Holdens as fitted to early P5B's by the coil but wiring mods are needed and you will need a starter solenoid cap with a ballast shunt terminal as well.

See SEARCH for more deatils

[Deleted]

Thanks for this information Phil. The trouble is I'm not an electrical wizard but a mechanical engineer, so I don't fully understand what is meant by needing a 'starter solenoid cap with a ballast shunt terminal as well'. Again, when I follow the links on the board I don't fully understand what to do.

I am fitting a Mallory Unalite with their maching coil and ballast resister, and it's the wiring of the ballast resister that plagues me. In simple laymen's terms what do I do? I am familiar with the wiring diagram and can see in principle where the ballast resister should be replaced, but how do I do it in practice (run replacement lead from ignition switch, or from starter motor connections???).

Secondly, what is the easiest way to replace distributer with the same timing position? I thought about setting No 1 cylinder to just spark by manually turning the distributer body round by hand, then doing the same with new electrinic distributer, checking it for 6 degrees BTC in the process. But I need the new coild wired up first.

I don't know whether a timing light connecting -ve side of coil to distributer connection would work on an electronic dizzy.

Dennis.

[Phil Nottingham]

Its unwise to connect anything to electronic kits unless the manufacturer tells you how. The best way is how you suggest except mark the sides of timig case and dizzy as well as noting the position of the rota-arm. Do not turn engine again until its refitted.

As to the ballast this is where you may have a problem. It does not matter where you mount it except it is best practice to mount it on or close to the coil. You must then run a new ignition feed from the unfused side of the Ignition Control of teh fuse box, or if you wish direct to the actual ignition switch (the white cable) but its more difficult.

Use 28 strand cable and run it in sheathing behind the heater box to the coil position which I am assuming you will mount where the old one (or should be) is on the nearside wing near the top? This goes to one of the terminals on the ballast (it does not matter whch) another cable then goes to the Coil. + terminal from the other Ballast terminal

The next stage is to run the "SHUNT" wihch is another similar sized cable safely out of harms way from the the coil + terminal to the solenoid on the starter motor. This will bypass the Ballast when the starter motor is energised.

If you are lucky on the solenoid on teh side of the starter there will be a unused Lucar spade terminal on it in addition to the large batter one and a smaller to the starter relay. If you are not lucky there will jst be a blob of solder! You can eutehr remove the motor and repace the solenoid cap with one with the extra Lucar male terminal on it or if you are handy with a soldering iron solder one or. You can even just solder a fly lead direct to it and use a bullet connector to conet up to the Ballast shunt cable.

Its best to test all this first with out connecting the coil -ve to the blacl box/dizzy. If you have a meter use it but if not use a 12 volt test lamp. Connect one lead (+ve if meter) to the + coil terminal and sitch on the ignition but DONOT turn to start. It should read 6 or 9v approx or the bulb will glow at 1/2 or 3/4 brightness. Then assuming you have ALREADY refitted the dizzy (or better still do all this before converting it) try the reading when turning over on the starter. The meter should read just about 12v or the bulb should be bright.

If you have not converted the dizzy you can use the old coil and it should start and run as before.

Make sure you tape the old coli feed out of the way. Be also very carefull to keep the new cables clipped well away from the spinnin/hot parts and very importantly from the HT leads which will blow the black box

You can dispense with the solenoid cap terminal if you use the realy/diode method described in an earlier thread but this is the "correct" and simplest way.

Also do not be tempted to use the new or old coil without the ballast, you can however use both without shunt with the new Ignition feed via the ballast and engine will start on the low voltage in most cases especially with the black box.


Make sure you follwo the manufacturers advice if anything is contary to mine though as you follow these instructions at you own risk

[Deleted]

Cheers Phil, that's very clear. I will follow that advice, I think, and use their suggested setup. Incidently, in the Mallory installation instructions it does say, 'If your vehicle is not equiped with an ignition ballast resister, instal a Mallory Ignition Ballast Resister, ' suggesting that I could utilise my resister already in the loom. I know I have a voltage drop to 6-9volt when leting go of the ignition key and the engine is running. And in RPI's (who supplied the kit) information sheet under 'Questions and Answers' it says, 'In case of an intact factory V8, with the ballast wire still in place, you will not need to install this external resister.'

I suppose, in the end, it all boils down to liability if the parts become faulty - what do you think?

Dennis

[Phil Nottingham]

You can therefore use the standard set up without any wiring mods at all as per factory instructions

[enigmas]

Dennis I just took a look a their recommended wiring diagram www.v8engines.com/faq-mall.htm#Wiring
The ballast resistor on cars originally fitted with points ignition was devised to go with a 'ballasted coil'. The reason was that during initial cranking (especially in winter) the starter would draw considerable current from the battery to the detriment of the ignition system...there would be a drop in voltage. A ballasted coil has a higher output. During cranking the ballast resistor would be bypassed (the starter is drawing a heavy load) and the feed would be direct to the coil. As soon as the motor fired (you automatically release the key activating the starter) power is directed to the coil through the ballast resistor.

You've spent quite a bit of money on this system and if it were mine, I would use their specified ballast resistor as its matched to the coil. If something then goes wrong you have recourse for a replacement unit.

If your having trouble finding the wires...run a fresh set.

The circuit diagram is not clear in identifying the purpose of the other wires to the coil positive terminal. One of these may still feed a full 12 volts to this terminal on cranking, although the instructions state that 12 volts should not be connected to the coil (i.e. restrict current flow to the coil). Since the voltage output is higher with this system and with a good quality battery I would leave the other wires disconnected, especially if you can identify one as a feed from the starter motor.

My Piranha optical ignition system runs unballasted using a standard coil. The 'Newtronic' module requires a 12 volt feed (no less than 9.5 volts during cranking).

Their web page also illustrates that some customers find the instructions lacking in detail.

[Deleted]

As a final note, Phil, I rechecked my voltage reading on the +ve side of the coli with a meter. Disconnecting the -ve connections on the coil there was 12volts with ignition on and with engine running, and 10.5volts when starter was engaged. A 1.5volt drop is accountable to the load through the starter motor, I expect, which means that, if my theorising is correct, whatever ballast is in place it cannot be very affective now. I will, therefore, rewire using the whole Mallory package.

Dennis.

[Phil Nottingham]

It's probably the best bet - old wiring and new electronics do not go together

[Warwick (Ozcoupe)]

Dennis,

Have you got a copy of stevem's simplified (and e-mailable) wiring diagram?

[eightofthem (Andy)]

Just to add on to this topic I am also fitting the same system to my motor.Does the dwell angle still have to be set with this system??. And do i just plug the vacume pipe?

[Deleted]

Hi Phil,

Having got my Mallory distributer working fine, with the ignition timing now set with a strobe gun, I have found the tachometer not working. Looking at the wiring diagram I'm not surprised - having put in a new feed supply for the ballast reistor on to the +ve connection on the coil etc., the original lead which has the tocometer attached is left disconnected.

I rang RPI Engineering and they said 'attach the original lead not to the +ve but to the -ve side of the coil. The more I thought about it, however, it doesn't seem right (surely it would mean a current, having original pink ballast in series, would be in contact with the lead to the distributor, thereby bypassing both the low tension circuit of the coil and the new resistor?).

Any ideas how I could get tachometer working on my new setup, i.e., by use of my disconnected original +ve from the ignition switch and my new lead from the unswitched fusebox to resistor and coil etc?

Secondly, on a general note: when engines fail through fuel vapourisation when too hot, what happens to make them difficult to start till they cool down?

Dennis.

[Phil Nottingham]

The rev counter wiring works by induction - I did not realise you had a coupe so what you must do now although I have not trialled this as I have not tried your set-up (an dsome systems will not work inductive Rev counters) is that you must loop the new feed you have fitted(?) via the rev counter in place of the existing loop which feed the ballast wire. Just unclip it and tuck well away as it is insulated. Use SEARCH if you want to see the pictures.

As to your fule vaporisation point the mechanical pump is just not up to coping with modern petrol especially when the operating lever wears slightly so reducing pumping capacity. The fule lines do get warm particularly when low tank level (as it has a spill return system that contatntly ciculates the warm petrol. The pressure is just too low to clear vapor. The diaphragm also becomes porous

Some have gone to endless trouble rerouting and insulating fuel lines without success

The only sure cure is to fit fit a high capacity Facet electric pump low down at the front of the engine bay (as these are noisy and constantly tick because of the spill return system) This also retains the reserve function. also check the reserve changeover valve is not partially blocking the lines if semi-seized.

Again both vaporisation and ekectric pumps have been covered endlessly in the past so see SEARCH

[eightofthem (Andy)]

I have fitted the mallory dizzy and coil (unilight) today but may have a problem.I have run a feed wire from fuse box (removed wire for under bonnet lights and used that terminal) to one side of the ballast ressistor supplied with the kit, also fixed one wire from dizzy to same side(red one).Then from other side run a wire to the coil +. However upon checking with meter i have 12 volts at both sides of ressistor and both sides of the coil. Is this correct if so whats the point of the ressistor?? I have not tried to start it

[johnwp5bcoupe]

May 17, 2008 16:45:56 GMT eightofthem (Andy) said:

I have fitted the mallory dizzy and coil (unilight) today but may have a problem.I have run a feed wire from fuse box (removed wire for under bonnet lights and used that terminal) to one side of the ballast ressistor supplied with the kit, also fixed one wire from dizzy to same side(red one).Then from other side run a wire to the coil +. However upon checking with meter i have 12 volts at both sides of ressistor and both sides of the coil. Is this correct if so whats the point of the ressistor?? I have not tried to start it

Have a read of what ozcoupe posted a few days ago if may help you understand there is 12v everywhere because nothing is under load

On a standard Kettering ignition system, the spark is produced by the coil which is two coils (windings) of wire in a canister and in essence, a tranformer. It increases the battery voltage of about 12 volts up to many thousands of volts. The points are the switch that applies the 12 volts to the primary winding of the coil. If you switch on a 12 volt supply to the coil, the magnetic field it produces in the primary winding induces another electric current in the secondary winding. This is the current that is fed to the spark plug.

However, if the points were closed whenever a spark was needed, the electric field and resultant magnetic field takes time to build up and nothing would happen in the time required. Therefore the whole thing operates in the reverse manner to what you may expect.

It's the changing magnetic field that induces the second current so it is created when the field is rising when the 12 volts is applied to the primary winding AND when it collapses when the 12 volts is removed from the primary winding. If the field is given time to build up it will reach a higher "strength" and when the primary (12v) current is turned off, the field collapses suddenly and this produces a large pulse in the high voltage secondary winding connected to the spark plug via the rotor button and distributor cap.

So when the points close the field starts to build up and when the engine needs a spark the distributor cam opens the points, the magnetic field in the coil collapses and a big high voltage pulse is generated and sent to the spark plug.

The longer the points remain closed, the more the magnetic field is able to build and the bigger the pulse sent to the spark plug. The dwell is the time that the points dwell in the closed position. Since dwell time is not constant - the lower the engine revs, the long the dwell time - dwell is expressed as an angle. That is, how many degrees out of the 360 available as the distributor spins through one revolution.

Since a V8 has to fire 8 cylinders in one rev of the distributor, then the dwell angle must be less than 360 divided by 8 = 45 degrees. You also have to allow for the points to move open and closed and all this "uses up" available degrees. So in the end we have about 25 to 30 degrees available for the points to remain closed for each spark plug on a V8.

Capacitor discharge ignition (CDI) or transistorized ignition modifies the Kettering system in the following way.

The points are used to operate a remote solid-state switching device (SCR - silicon controlled rectifier) which does all the heavy work. Only enough current is passed through the points to stop them corroding or oxidizing. This is called a wetting current and it keeps them clean without being strong enough to burn them or pit them. Therefore they last a long time without needing adjustment since the contacts don't get "eaten" away.

The 12 volt supply that is normally fed through the points is used to charge a large capacitor. This is a bit like a short-term battery and it holds an electric charge. This charge can accumulate for the entire time that the spark is not required. In other words it's like being able to extend the dwell much closer to 45 degrees. When the points open, the SCR dumps the big charge into the coil quite suddenly so the speed of the rising magnetic field is as fast as the previous collapsing one and a hefty spark is delivered to the plug at a much higher voltage and duration than before. The coil is now operating in reverse, so to speak.

Because of the higher voltage and current produced, it is possible for the pulse to jump through insulation that is marginal therefore if CDI is fitted, spacing between plug leads is important so as to minimize the risk of cross-fire by the "spark" jumping through the lead's insulation and firing the wrong plug. Cross-fire can be a problem on early Range Rovers, even with standard ignition, and you can burn a hole in the top of a piston. Also, if a plug lead becomes disconnected and that spark has nowhere to go, it can jump through the internal coil insulation and burn out the coil.

The next step beyond this is to replace the points themselves with an electronic switch using an optical sensor (Lumenition) or a Hall effect device that sense a rotating metal lobe.

The final evolution is to use a coil for each spark plug and have the blackbox fire the appropriate coil and its plug thereby eliminating the distributor.
« Last Edit: May 7, 2008, 1:27am by Ozcoupe »

[eightofthem (Andy)]

Thanks john, but thats far to much for my tiny brain to understand!. Electrical things are not my cup of tea.I was under the impression reading other threads on this subject that 12 volts into ballast would come out other side at 6-8 volts.I am just worried about damaging an expensive kit by putting to much voltage into it.

[johnwp5bcoupe]

Ok Andy if the suppliers say 12v at the input to the ballast you can't be wrong as the circuit draws current the voltage will drop accross the ballast etc and will go up and down every time the dizzy needs to produce a spark but you will not see it on a DC meter very well a scope this is the pulse the rev counter sees if you have followed the instructions you can't go wrong Good Luck

If you can scan in the connection details email them to me