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Where is the ignition ballst and drive resistor?

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cokerart Avatar
cokerart Bob Coker
Atlanta, Georgia, USA   USA
1973 Triumph GT6 MkIII "Spit-6 Or Dr. Frankenstein"
I have a 1973 GT6 engine in a 1980 Spitfire. After rebuilding the engine, I can't get spark out of the coil.

12 volts are feeding into the coil. In fact, I have 12 volts at both the positive and negative sides of the coil. I have a Crane X700 electronic ignition and have spent a great deal of time trying to figure out why there's no spark coming out of the coil.

A friend has offered to lend me a spare TR6 'points' distributor to see if, by reverting to the OE style, we can get it to start.

Now, I need to reconnect the Pink/White wire to an ignition ballast and the 'Drive Distributor' to complete the circuit. But where should I look for these?
http://www.triumphspitfire.com/images/wiring/78diagram.jpg
This wiring diagram shows the 'Drive Distributor' in line with the ballast wire and the distributor. What does it look like and where should it be?

-Bob

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TDHoward Tracy Howard
Radford, VA, USA   USA
1971 Triumph Spitfire "Was "rusty", Now "Spitty"
1980 MG MGB MkIV "Emma Peele"
The ballast resistor on my stock 71 is physically located below the coil mount, on the fire wall.

A ballast resistor is essentially a wound resistive wire enclosed in a ceramic case. They are usually natural (off white)color ceramic, unless it's burned then it's brown.

They are a stock item at any FLAPS, and should be used only IF the coil requires it.

If you have a coil that says "EXTERNAL RESISTANCE REQUIRED" it uses 6 volts to run, but 12 volts to start and during the start cycle the resistor is bypassed.

IF the coil says "NO EXTERNAL RESISTANCE REQUIRED" you don't need it.

CAUTION on some cars the resistor is in the form of a resistive wire. But it's necessity is ALL dependent upon the needs of YOUR coil.

cokerart Avatar
cokerart Bob Coker
Atlanta, Georgia, USA   USA
1973 Triumph GT6 MkIII "Spit-6 Or Dr. Frankenstein"
I have an ACCEL 12v coil. No mention as to whether it would require a ballast. A mechanic replaced the gold Lucas aftermarket coil with it. I tested both coils with the same result. Do you think I could forgo the ballast wire altogether?

I'm starting to think there may be a fault with the electronic ignition unit, though it worked fine (Or so I thought) before the rebuild.

-Bob

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TDHoward Tracy Howard
Radford, VA, USA   USA
1971 Triumph Spitfire "Was "rusty", Now "Spitty"
1980 MG MGB MkIV "Emma Peele"
If its a 12v Coil there is no need for a ballast resistor.

BUT, somewhere on the coil itself, it should say something to the effect of No external resistor needed.

I know Accel makes both kinds.

spitfire50 Avatar
spitfire50 Paul Mugford
Rochester, N.H., USA   USA
Bob,
Try using a multi-meter on the ohms scale on the primary coil terminals with the coil disconnected. If you get a reading of about 1.5 ohms it is a 6V coil and needs a ballast resistance. If the reading is about 3 ohms then it is a 12V coil and can connect without a ballast resistance.
Good luck,
Paul

landrover Avatar
landrover Michael Loiodice
Upper Marlboro, MD, USA   USA
Bob..

That pink/white wire should be a resistive wire - it is the ballast resistor.. And, I believe it would normally be the white/yellow connected to the coil.

If you are using the Crane setup, doesn't it have a pickup in the distributer? (Mine does). If so, you don't need the drive resistor as that is part of the original electronic ignition.

Check the coil with an ohmmeter as mentioned in the previous post - or research it through Crane.

Connect the Crane unit according to the Crane instructions. Assume for the moment you have a 12V coil and don't need a ballast resistor. Do NOT connect any of the car's wiring harness to the coil just yet. Run a wire from the battery + terminal directly to the coil + terminal. See if it will start. If so, then you need to pick up voltage from the WHITE wire circuit and forget about that pink/white.

Going back to your Previous Post from a few days ago - you said your solenoid did not have the connection for the white/yellow wire - so hopefully you have a 12V coil there.

If you do have a 6 V coil - the white/yellow should work - BUT - you do need to get the correct solenoid.

Cheers
Mike

cokerart Avatar
cokerart Bob Coker
Atlanta, Georgia, USA   USA
1973 Triumph GT6 MkIII "Spit-6 Or Dr. Frankenstein"
Mike, as you might guess, I've been doing a lot of reading on this subject.
As I understand it, and from your post above, the ballast resistor IS the Pink/White wire. (Is it unusual that I'm getting 12 v from both the [+] and the [-] sides of the coil???)
Dan Masters provides an excellent explanation that reinforced what you have been telling me:
http://www.vtr.org/maintain/ballast.shtml

The coil is definitely 12 volt:
http://www.accel-ignition.com/ProductDetails.aspx?MajID=505&MinID=5056&productID=6985&txtSearch=8140
It was installed by the previous mechanic (PM), who was certain that the existing Lucas gold coil was bad. I now have my doubts about his judgment, but that's an entirely different issue.

The Crane ignition system was installed by the PO before I purchased the car and seemed to work fine until the rebuild. My 5.0L buddy's plan is to install a spare TR6 distributor with the OE points set-up. The idea being just to see if we can get it to run the Old School way. If it will, then it would seem that the Crane unit might be fried.
We'll know today. Wish me luck.

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rhitee93 Avatar
rhitee93 Brian Dougherty
IN, USA   USA
Bob,

If you are getting the same voltage on both sides of the coil then no current is flowing through it. Did you check the ground side?

landrover Avatar
landrover Michael Loiodice
Upper Marlboro, MD, USA   USA
In reply to a post by cokerart Mike, as you might guess, I've been doing a lot of reading on this subject.
As I understand it, and from your post above, the ballast resistor IS the Pink/White wire. (Is it unusual that I'm getting 12 v from both the [+] and the [-] sides of the coil???)
Dan Masters provides an excellent explanation that reinforced what you have been telling me:
http://www.vtr.org/maintain/ballast.shtml

Yes, pink/white is the ballast resistor. It is a resistor wire.

+12V on both sides of the coil suggests that you are putting +12V on the coil and you have no ground.. If you had points, you would see a +12V potential on the (-) side of the coil if the points were open. When the points close, you have a ground on the (-) side of the coil and would read zero volts there.

With the Crane ignition connected, I don't know off-hand what you should see on the (-) side of the coil.

I don't have a whole lot of experience with the Crane. I bought my car as a non-runner - electrical system all disconnected. The Crane has Red, Yellow and Black wires. Red is marked "Coil+", Yellow is "Coil-" and black is ground. That looks pretty straightforward. I don't know it has to have +12V or can function on +6 volts.
Check this reference on installation in a Jag.
And this reference which shows installation in a spitfire.

Both use a ballast resistor.. I would be contacting Crane and asking if you need the ballast resistor with their unit if you have a 12V coil.

In reply to a post by cokerart The Crane ignition system was installed by the PO before I purchased the car and seemed to work fine until the rebuild. My 5.0L buddy's plan is to install a spare TR6 distributor with the OE points set-up. The idea being just to see if we can get it to run the Old School way. If it will, then it would seem that the Crane unit might be fried.
We'll know today. Wish me luck.

At this point, that sounds like a good plan.

Of course, we are looking a real obvious duhhhhh point.. Do you have your timing all set up correctly?

Cheers
Mike

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rhodyspit75 Avatar
rhodyspit75 Ernie Connor
Cumberland, RI, USA   USA
I am not sure about Crane but one of the great destroyers of electronic ignitions is leaving the key on without the engine running.
In your posts about your oil and ign lights being on all the time you had actually been providing power to the coil the whole time the yellow/ white wire was plugged into the spade on the solenoid. It is possible that at some point the pickup was in the position to cook the electronics.
It seems more likely since it ran previously.

landrover Avatar
landrover Michael Loiodice
Upper Marlboro, MD, USA   USA
Good point, Ernie. I had not even considered that.

Yeah Bob, try out the conventional ignition if you can and get the car running. You still are going to need to sort out power going to the coil but for testing you can still just bypass the harness wiring and wire 12V to the (+) terminal on the coil.

Cheers
Mike

younggene Gene Young
Huntsville, AL, USA   USA
This is my first post.

I am putting together a 1979 Spitfire given to me by a relative-in-law if I would come and get it (150 miles round trip). The Commission number is Fm99906 U. It was mostly yellow when I got it with rust and some Carmine Red (original color) showing through. It is now painted with a late Ford truck color close to Carmine Red but with a metallic. Looks really good. A photo will be provided a little later.

The body and the motor/gearbox were separately on the ground in a shed when I picked it up. The motor has been mostly restored. I still need to mount fuel pump, water pump. input and exhaust manifolds, carburetor, alternator and miscellaneous. Four speed gearbox is mostly rebuilt (been difficult).

The carburetor is Zenith CD with automatic coolant driven choke.Both metal coolant pipes feeding auto choke and heater are unusable. Can obtain the long one (from water pump) from SpitBits. Anyone have suggestions?

It's my understanding that it was originally equipped with a Lucas electronic distributor. I have a distributor with a broken case that is Lucas that I think originally had electronic ignition; missing parts inside.

I have had trouble interpreting the ignition system schematic with respect to the ballast resistor and the Drive resistor functions. From my interpretation of their functions, it appears to me that when the starter was engaged, the electronic ignition was powered through the ballast resistor; and when the ignition switch was rotated to the drive position, power was applied to the electronic ignition through the Drive Resistor. Comments appreciated.

Thanks for reading, Gene in Huntsville, AL

Doug in Vegas Avatar
Doug in Vegas Douglas D
Las Vegas, NV, USA   USA
People tend to power their external electronic ignition module to the power for the coil.

If you do this you will be powering a 12v circuit at half power.

If you have an external module power it off a white wire.

TheZster Avatar
TheZster Steven Z
SAINT LOUIS, MO, USA   USA
1978 Triumph 1500 "BLK-BRY"
[quo The Crane ignition system was installed by the PO before I purchased the car and seemed to work fine until the rebuild. . If it will, then it would seem that the Crane unit might be fried.
We'll know today. Wish me luck.
[/quote]


No such animal as chance... this is a matching coincidence.... Something (god knows what). happened when you reconnected....

I'm thinking - if you're getting 12 v to the coil Plus side.... and your distributor is hooked up properly... and the coil is properly grounded on the - side.... Your coil might have issues....

I've got a 12 v pertronix... but - if I leave the original resistor dropping to 5.5 volts on the positive side - it still fires - though a bit lethargically.... Naturally, I dropped the resistor - but point being... it still fired.....

Z

spitfire50 Avatar
spitfire50 Paul Mugford
Rochester, N.H., USA   USA
In reply to # 1510895 by younggene This is my first post.
I have had trouble interpreting the ignition system schematic with respect to the ballast resistor and the Drive resistor functions. From my interpretation of their functions, it appears to me that when the starter was engaged, the electronic ignition was powered through the ballast resistor; and when the ignition switch was rotated to the drive position, power was applied to the electronic ignition through the Drive Resistor. Comments appreciated.

Thanks for reading, Gene in Huntsville, AL

Gene,
The ballast is cut out of the circuit when cranking. It only works when the ignition draws power through the run terminal of the ignition switch. When cranking the solenoid switches a line from the battery directly to the coil bypassing the ballast.
The drive resistor is a separate part of the electronics mostly mounted to the distributor. The drive resistor either took up too much space to fit, or it rejects too much heat to share the box on the distributor.
The ballast allows a 6 V coil to run on a 12 V system and gives a boosted voltage when starting.
The drive resistor is part of the circuit which switches the coil on and off to make the spark.
All the best,
Paul

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