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Ballest resistor ignition


Andrew
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A std 12volt coil has a primery resistance of 3 ohms and coil runs at 12v all the time

if your car has a ballasted system it has a resistive feed which drops the running voltage to 6-8 volts these have a resistance of 1.5ohms

when you crank the engine it feeds 12v to the coil to give a higher HT only when starting

this feed comes from the starter motor solenoid terminals with a white yellow wire

the coil may have a seperate ceramic dropper or a coil feed with a white /pink trace

 

if you run a 6 v coil with 12v feed you make very high HT more than our dizzy will take and burn points or blow the electronic unit as the current is now doubled

 

if you run a 12v coil with a balasted 6v feed you get weak HT and elec units likely to missfire

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Hello to all

I need to purchase a new ignition coil which I will purchase from the club shop as I believe in supporting the shop whenever I can. Can someone explain the difference between a ballast resister ignition/coil

and a system without.

Regards Andrew

 

Hello Andrew,

 

A coil that uses a ballast resistor operates at a voltage lower than 12Volts. On starting, a second feed provides 12Volts to the coil which gives a stronger spark. Once the ignition key returns from the starting to running position, the coil feed reverts to the lower Voltage. So if you have only one wire on the +ive terminal your coil will be non-ballasted and if two, ballasted. Unless of course you have an electric tacho which is connected to both contacts. Another way of checking is by putting a meter on Ohms between the +ive and -ive contacts of the coil. It should read 1.5 for a ballasted coil.

 

Beat me to it Pete!

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A bit of thread drift, I have a ballasted system, it has a resistive wire rather than a resistor. There must be a fair bit of current going through it, keeping the loom nice and warm! I wonder if I should replace it with a resistor, or am I worrying unnecessarily? Where are my worry beads?

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A bit of thread drift, I have a ballasted system, it has a resistive wire rather than a resistor. There must be a fair bit of current going through it, keeping the loom nice and warm! I wonder if I should replace it with a resistor, or am I worrying unnecessarily? Where are my worry beads?

 

Why not replace the resistor wire with a normal cable and fit a 12Volt coil? This opens the way to electronic ignition and all the benefits. Just a thought.

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Ive just been out to help a local area car wonderful spitfire 1500 been owned for a few months , someone put alot of time and money into this car but.....it failed and AA could find the problem other thana aweak spark guess what...

it has a aldon electronic fitted, a ballasted feed , a 3 ohm 12v coil and some nasty resistive plugs with an R in the suffix and the coil reversed polarity

so it has all the wrong things going for it , add a choke not returning and no wonder she faulted

easy to fix , add an12v feed use the 3ohm coil fitted add some std spark plugs, and connect the coil rightway round

and bingo ,, she runs

 

pete

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Ive never come across a  built in  resistive  wire give any trouble . if you left ign on with points closed for ages i guess it warms a little

 

 

you keep the ballasted coil it may benefit the aldon to give it a 12v positive feed

 

they used to specify their operation voltage range but cant see it now, used to be like   6 -18 volts I have seen cars when the battery state is low in  the cold that the thing misfires as its dropped below the low end of the range ,  giving it a 12v feed to the ignitor solved it all 

 

I  am going to re wire this Spit as its got 6v to a 12v coil  and they dont want to buy a coil either ....its catching  Ha!

 

so  its snip snip  crimp time 

 

Pete

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  • 4 weeks later...

My 13/60 is fitted with a Magnetronic ignition system and the coil recommended to go with it. The coil is fed via a ballast resistor, provided in the kit. On no account must the coil run without the resistor. The car starts instantly whatever the weather and runs well. The system has been on the car for about 3 years now, with no problems. Cheers, Dave.

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some nasty resistive plugs with an R in the suffix

"R" suffix or prefix...?

 

Nothing wrong with using R prefix plugs in one of our cars - and a few benefits if you're using electronic ignition/radio/satnav/etc.  They just have a resistor built in to reduce electrical noise that can interfear with other electical systems in the car.  About the only factory/dealer-fit item that could be helped is the radio but many of us have added more than that these days.

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Down to preferance but from problems i have had to solve its cured running problems on many cars misguidedly fitted with plugs with a Resistive R in the title

Most resistive plugs need a modern coil with 32kv+ when running on our stuff at 22kv they

dont fire properly

 

been proven to cause many a misfire and weak performace , you need all the Ht we can get without sticking your finger in the dyke.

 

if you run megajolt youre in a better place to use them

 

pete

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At vast expense I bought the Aldon electronic ignition kit that goes with what I have. So, I aint  buyin' no new coil! :lol:  No, I just thought I'd replace the resistive wire with what went before. I'm not keen on having a heating element embedded in the wiring loom.

 

Sorry Doug - didn't see this before now. The point of the resistance wire is that the same amount of heat is spread out all along the wire. So there's hardly any heat in any one place - find it at the coil end (engine running) and see if it's even warm! This means that it's a relatively low-stressed component and therefore fairly reliable. Compare this with a power resistor which would dissipate all the heat in one smallish component - possibly bolted to the bulkhead to try and get rid of it. Big(ger) temperature rise generally means less reliable. The other advantage for the manufacturer is there's only one component (the wire) instead of 2 (plus connectors, plus mounting) so it's cheaper.

 

Having said that, my Dolly ignition failed - wire high impedance - fortunately at one end so I just shortened it a couple of inches.

 

Cheers, Richard

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Down to preferance but from problems i have had to solve its cured running problems on many cars misguidedly fitted with plugs with a Resistive R in the title

Most resistive plugs need a modern coil with 32kv+ when running on our stuff at 22kv they

dont fire properly

 

been proven to cause many a misfire and weak performace , you need all the Ht we can get without sticking your finger in the dyke.

 

if you run megajolt youre in a better place to use them

 

pete

 

 

Pete,

 Would you also recommend using copper cored spark plug leads as well as non R plugs in a non electronically fueled and fired OEM system?

Running an engine with copper cored cable and non R plugs will produce a lot of interference, locally and remotely i.e the house you drive past.

 

I suspect R plugs would "lose" less than you think. 

I have EFI, so non resistive plug and leads is not a route I would take.

 

Cheers,

Iain.

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since MW stations disappeared and VHF became the norm  Ive never ever come across interference from anyone, any car or vehicle not even the odd crap motorbike that does 60 up our 20mph street.  , you can remove all the aftermarket suppressors and it makes diddly squat change.

copper went out with the arc even triumphs would have in most of their years would have used carbon cored HT leads

 

I base my finding on the experience of cars that turn up with me for some magic fix and the misfires are transformed when you remove the  'R'offenders

i dont suspect it makes little difference I know it does , got plenty of Tee shirts for this problem 

 

I stick to basics  they work and are proven by years of developement,  we all like to play about and reckon 'thats better' but in most cases of aftermarket twiddling the result is actually lesser,  but we dont admit or test against the clock to prove or disprove,  

 

what we cannot do is replicate a  car manufacturing experimental and development and test recording facility like Triumph and all outhers had in their day.

the testing might be 40+ years ago but if you stick to the spec it works ....for another 40 years  

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The ballasted ignition system was produced to prolong the life of contact breaker points.

 

The original 12V through a 3 Ohm coil meant that the points were carrying about 4 Amps, when that type of contact is really only fit for less than 3A.

It hadn't changed in the fifty years since Charles Kettering demonstrated points ignition to Cadillac, and required a points check every 1000 miles or so.

6V through the coil and points enabled a much longer maintenance period, as the amps were halved, but would have led to a weaker spark, if the coil resistance had not also been halved.

 

Then, later, Transistor Assisted Contacts ignition used a semiconductor, triggered by the points, to switch the coil on and off, enabling even less current at the points, and then pointless (!, better 'breakerless') ignition came in, and kits like the "Magnetronic" (also Lumention, Optronics etc) appeared that allowed previous types to be upgraded.  All in the search for longer points life and less dwell variability. 

 

So care when mix'n'matching coils and modified ignition modules.    The ballast, either in a wire or a resistor was a stop-gap, and can be (should be?) removed, as better and more reliable ignition  is available for our cars.

 

John

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Pete,

 do you think that the ~5000 ohms resistance of the R type plugs was reducing the power or output voltage at the plugs, and this was causing a problem? I doubt it.

When you have swapped out R plugs for non R plugs and the engine ran better; maybe it was for another reason?

 

John,

 the running current thru a ballast system and a non ballast system is (about) the same. The points switch the (about) same current. But during starting, the ballast system switches a higher current and the non ballast system switches a lower current.

 

Cheers,

Iain.

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Iain,

Quote me, "6V through the coil and points enabled a much longer maintenance period, as the amps were halved, but would have led to a weaker spark, if the coil resistance had not also been halved"

 

So, yes, the current would have been the same.  And  Triumph's use of a ballast resistance and low resistance coil was ONLY to provide a hotter spark at start-up?

 

JOhn

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Hi John,

 Yes as you said. The ballast system coil would be supplied with an "over voltage" all the time the engine was cranking.

 

If anybody has or wants to run points; An improvement in output voltage will be realized if the points condenser is matched to the coil. The telltale that the condenser and coil are not matched is seen when looking at the points contact surface prior to replacement. Both contact surfaces will look the same on a matched system. One contact will have a "nipple" and one will have a crater, when the condenser value is not matched. increasing or decreasing the condenser value will correct this. I cant remember which way.

 

Cheers,

Iain.

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