Ballast resistor or not - GT6 Mk 3

[dellyend1]

Hi , have a newtronic electric ignition on the 6 that was installed by the previous owner. The current set up is a non ballast resistor coil. The coil is getting pretty hot , which as I understand it is the oil heating as it reduces the incoming supply. I can see the yellow / pink wires that should go to a ballast resistor but I am unsure that if I add a resistor back in am in just fiddling and likely to fry something ? Pics of electronic ignition box and current coil below. Many thanks . Jeremy

[Pete Lewis]

coils get hot due to the energy they handle  the oil is there to cool it down,  on a 6 cly the ccoil is mounted on the block and will get as hot as the engine, or reverse the thought and the coil is cooled to the same as engine temperature

I have not come across the newtronic system but google brings up lots of clues 

you need to copy /download their manual and check out the wiring 

the white yellow would go to the cranking terminal of the solenoid as  the 12v boost when cranking in a ballasted system

is the ballast connected at all    and if not but has a full 12v feed then the coil needs to be changed for a 3 ohm coil  not the 1.5 used for 6volt ballasted .   if thats the case yes you could fry a few things due to the higher amps used 

sorry neds a bit of homework to identify just whats going on    whats the spare terminal hanging around for ???

Pete

[chrishawley]

If you've got two wires coming out of the loom then presumably this is an early GT6 with (or did have) the external ballast resistor. One wire should be white (to the 'in' side of the resistor) and the other should be white/yellow (to the 'out' side of the resistor).  Later GT6s has resistance wire built into the loom so there's only one wire, white/yellow, going to the coil.

The coil for a ballasted system is designed to run on 6 volts and has a resistance across the primary windings of approx 1.5 ohms

The coil for a non ballasted system is designed to run on 12 v and has a resistance across the primary windings of approx 3 ohms

If the coil is getting silly hot then the setup maybe feeding 12v to a  coil  intended for a ballasted setup which ought only to be receiving only 6v.

Proceed with confidence - there's no potential for doing any damage here.

For myself I would

* Check voltage at white wire to be 12v  (i.e. not been messed around with by PO). White/yellow wire will only have volatge when engine cranking)

• Check ohms across coil. If 1.5 ohm then install ballast resistor as a necessity. If 3.0 ohms the either a) leave as is, as a non-ballasted system or b) replace with correct coil and install ballast resistor.

 

By a, modest, margin ballasted systems are better than non-ballasted. Somewhat better starting under cold cranking conditions and more reliable spark at high revs due to lower inductance. But it's not big a deal; there's plenty of pre 1970 cars run perfectly nicely on non-ballasted systems.

 

P.S, If installing a BR the two wires need to be the right way round on the resistor otherwise the resistor will be bypassed and it'll be 12 v all the time.

[chrishawley]

Addendum to prev post.

Only just occurred to me that that the electronic module is getting its power feed piggybacked off the + terminal of the coil. (red wire)  This may well mark out that unit as requiring a 12v power feed - which may be why that ballast resistor was removed in the first place. In which case the power pick up the EM would need to be from the 'in' side of a ballast resistor (12v) rather than the + ve of the coil which would now only have 6v.

 

[JohnD]

As Pete says, some homework needed, and your text  should be the Newtronic Installation Instructions.    But I had a look online, and what is available is confusing.   So, as a service to Triumph, and to you, they are below.

By the way, "The coil is getting pretty hot , which as I understand it is the oil heating as it reduces the incoming supply"       Yes, the coil is a transformer, that works hard to do it, but "reduction"?      It converts your 12V or so from the battery/alternator, to 50,000V or more!

The original "ballasted" system was a bit of either Triumph penny-pinching, or weirdness.       As Pete says, it used a coil for 6V, that was connected directly to 12V  on starting, "over-clocking" the coil to boost the High Tension voltage on the high tension side, but which during running ran through the resistance, to reduce the volts at the coil back to 6V.      The resistance was a length of special high resistance wire, see the wirirng diagram in your workshop manual.    AFAIK, on six cylinder engines this was only fitted to the Mk3 GT6, and was, IMHO, a retrograde step.    Ensure you have a 12V coil as Pete describes, and discard any additional wiring.

Good luck!

JOhn