10 replies to this topic

[andyt]

Is there any down side to using the ballast resistor type coil? All i know is it uses a 9 volt feed to the coil instead of the regular 12 volt system.

Can you convert to the usual 12 volt coil is there any advantage?

 

Andy.

[richmondclassicsnorthwales]

I suppose you have heard the supposed advantage of this system, but I am not a big lover.

 

You can go to a straight forward 12v all round system, I have this fitted myself, as I did not feel the spark was strong enough from the ballasted system.

 

Really, a 12v feed, via ignition switch to the + side on the coil., It already has it's own earth, so no need to do much more.

 

I felt it had better starting, normally, first turn of the key as opposed to a 2nd bash at starting, that's me, but I thought it was a lot better.

[dklawson]

As above, I assume you have read up on the differences and why the ballast system was introduced.  

 

EDIT:  I wrote a lengthy response and then decided it would be better to ask questions instead.

Are you contemplating changing coils or do you think you need to replace your car's coil?  What is your end goal?

Edited by dklawson, 01 June 2016 - 12:23 PM.

[andyt]

I'm changing my coil as the original had failed and was thinking about the pro's and cons of keeping the ballasted system or changing completely to the 12 volt coil.

[Cooperman]

The biggest downside to having the 9 volt coil is the pink/white resistor wire which goes from just after the ignition key to the coil inside the front loom.

Now that wire has a propensity for overheating and taking most of the front loom with it. The result is a major re-wiring job and the last one took me 6 hours to do and even then I found I didn't have all the correct colour coded wire.

I have done this repair 3 times over the years and I always change to a 12 volt coil when doing the repairs.

Never understood what the perceived advantage of the 9 volt is. After all they 9 volt only ran for a short period.

[CityEPete]

In theory the 9v when running makes no difference to having 12v, but the ballasted version gets the full 12v when starting giving it more oompf when the starter steals the power, effectively around 9v during start the same as running where a non ballast might perhaps only get that same 9v during starting so you get a crap spark just when you need it most.

I'd fit an electronic ignition kit and matching sports coil along with a new ignition wire to suit, set the timing, job done.

[dklawson]

The ballast ignition advantage was not the 6V to 9V mode (which is what the coil operates at during driving).  The advantage was the supply of a full 12V to a lower voltage coil during cranking on the starter.  This creates a hotter spark to assist starting, particularly in cold weather.  The system does work well for other car makes.  The biggest question for me is why some BMC/BL cars got the white/pink resistor wire (with all its problems) while some Triumph cars of the same period used an inline, ceramic, wire-wound ballast resistor that over the years has proven to be much more reliable.

 

AndyT, you said your coil has failed.  How have you tested it?  Coils are often blamed for all sorts of ignition problems that originate elsewhere.  I assume your engine is not starting.  When did it last run, what has changed since then, and how have you been troubleshooting the problem.  How have you determined the coil is at fault?

 

EDIT.  CityPete and I appear to have been typing at the same time.  The electronic ignition option is a possibility.  However, don't make the switch until you troubleshoot the problem you already have.  Get the car running with its factory setup before moving on to additional changes.  Avoid the shotgun approach of replacing everything at once to make the problem go away.

Edited by dklawson, 01 June 2016 - 08:46 PM.

[andyt]

Hi dklawson, when I originally bought the car 8 years ago it had starting issues so a borrowed replacement coil solved this problem but I also took the car off the road at the same time for a major rebuild! Now that i'm nearing the end of this process I found that I hadn't purchased a replacement, now I had heard there were problems with the ballast system and didn't know how or why I should change to the 12volt only system.

[dklawson]

If you have to buy a new coil anyway, most people will change to a standard 12V coil and change the coil wiring rather than retain the ballast coil and its wiring.

[andyt]

Ok thanks, does this involve just running a new 12volt supply from the fuse box?

 

Do I need to cut the pink/white wire out of the loom or cap it off and secure it out of harms way?

[dklawson]

For safety I would remove the white/pink wire at the coil and tape off its terminal.  Once disconnected with its terminal insulated it poses no threat.  

 

And, yes, run a new white wire from the fuse box to the coil (+) terminal.