Had a quick look at the coil on my car, and it has 2 wires running frm the
positive terminal, so I guess I have a ballast resistor working through a 12
volt coil
I think I will swap over to the correct one, and see what happens!
Cheers
tim
"alemen@pop.ftconnect.com" wrote:
> Tim, on later cars there is no obvious ballast resistor as it is part of the
>wiring (not sure when that was started but it could well be on your 75). I
>believe the +ve coil terminal will have 2 wires running to it if it does and
>by memory the one with the ballast resistor is or has pink/white and the one
>from the starter solenoid has yellow/white or gray - I'm going by memory
>here). If only one wire then there is no resistor. With the ignition on and
>the -ve side of the coil momentarily shorted to ground mmeasure the voltage on
>the +ve side of the coil. (disconnect the HT lead or take if of the
>distributer and short it to ground. I normally just leave if off so I don't
>fire a plug.)
>
> For a ballast resistor (nominally 1.5 ohms) and a 6v coil (also nominally 1.5
>ohms) the voltage will be about 6 volts (i.e. half battery voltage).
>
> If the voltage is about 12v (i.e. full battery voltage)then there's no
>resistor.
>
> If the old coil is truly a 12v coil (3 ohms I believe) but there is a ballast
>resistor in the wiring then it would be about 8v (i.e. two thirds battery
>voltage)on the +ve side of the coil. This is an incorrect configuration as it
>should be one of the other two above. It would work, just less spark than you
>hoped for.
>
> Should be relatively simple to figure out.
>
> Hope this helps.
>
> Alan
> '76 spitfire (with hidden ballast wire)
>
> Original Message:
> -----------------
> From: T. .R. Dafforn td214@cam.ac.uk
> Date: Mon, 17 Jul 2000 12:43:46 +0100
> Subject: Which Ignition coil & spinning distributors..!!
>
> I order to rule out all possible factors as per why sophie pops and
> 'kangeroos' when warm, I decided to change all bits of the ignition (the
> stuff which is on the car currently is of indeterminant age and quality
> Anyhow before doing this I ran the car to temperature just to check the
> temperature sensor (another story).
> As I was running it I heard a rather unhealthy grinding noise then
> normal tappety engine noise, another grinding noise, and the distributor
> spun in its seat, and the car stopped.... Well frightening...
> Investigations shows that the screw holding the condensor to the
> baseplate had come loose and jammed between the distributor shaft and
> the body... Stripped down the distributor, no damage except for a
> knarled screw. replaced the condensor and scew, and things seem fine.
> Should I be worried about any lasting damage?
> Also I was going to replace the coil, and so have bought the one listed
> at the part store (1975 1500 - 6v coil)...
> However i have noticed that the one I am currently running is a 12v
> coil. SO I guess I have no Ballast resisitor and hence a 12v coil...
> is this right?
> As to the Kangerooing, I found the manifold bolts were only finger
> tight!! So have tightened them and retuned and will see what its like
> tonight!
> cheers
> Tim
>
> --
> Tim Dafforn
> Structural Medicine
> Department of Haematology
> CIMR
> University of Cambridge
> Wellcome-MRC Building (Level6)
> Hills Road
> Cambridge
> CB2 2XY
>
> Tel. (01223) 336829
> Fax. (01223) 336827
> http://smokeroom.cimr.cam.ac.uk/
>
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--
Tim Dafforn
Structural Medicine
Department of Haematology
CIMR
University of Cambridge
Wellcome-MRC Building (Level6)
Hills Road
Cambridge
CB2 2XY
Tel. (01223) 336829
Fax. (01223) 336827
http://smokeroom.cimr.cam.ac.uk/
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