Mur,

Did you "...throw some work into a pertronix/1-2-3/ electronic ignition FAQ?" (your post from Oct 4, 2011).  I have a Pertronix Ignitor and an MSD Blaster 2 coil and the coil gets hot in a hurry.  I do not know if a ballast resistor is needed and if so what resistance.

Thanks, Keith

I am heading out the door to the hot rod shop that carries pertronix and thought I would do a search on coils before I left.  

I'll throw some work into a pertronix/1-2-3/ electronic ignition FAQ.

A Lucas sports coil, gold, maybe a recently manufactured unit, failed on my 1300 equiped 1990 car yesterday.  The car has had a 1-2-3 for a long while, though it isn't driven too often.  The coil failed while the car was running; I was literally climbing into the car when it shut off.  It is nice when a coil dies fully dead like that; instead of sort of hanging on. 

I am not familiar with there being a blue or gray wire with red stripe on coil (+).  The white wire on coil (+) indicates that your wiring is for a standard ignition system with a 3 Ohm coil.  However, you can use a ballast coil as long as you include the resistor in series with the white wire... as it sounds like you did. 

The ballast resistor will not affect the tachometer. 

I checked the two wires to the + of the coil.  One was white, the other was a light blue or gray with a red stripe.  I will admit that the previous owner has done some rewiring so not sure if the colors really mean anything anymore.  Anyway, I put both in series with the resistor, installed the new distributor and the car so far runs great! (knock on wood).  The coil doesn't get hot.  The only problem I see is when I start it or if I have the idle below ~800 rpm, the tach needle starts bouncing and fluttering a little (actual rpms are steady, just the tach needle going crazy).  This goes away as soon as I get the rpms above ~1000.  I know one wire from the - side of the coil goes to the tach, so wondering if the resistor is doing something to that circuit.

I'm going off memory and will double check tonight, but I think one is a white wire and the other is red/black.  Probably the white is coming from battery and the red/black went to my old points.  since I don't have the points anymore, I don't think that wire is even needed.  But will check to make sure.

 

Tell us a bit more about the two wires with one connector that are on coil (+).  What color(s) are the wires?

If the wires are both white, yes, you can connect the ballast resistor in series between the coil (+) terminal and the two wires in the harness.  If the wire colors are not white, then the wiring probably needs to be different.

Simple series wiring of the ballast resistor will not give you the easy starting of a ballast ignition system but it will still work.

Ok, just to be on the safe side, I bought a 0.7 ohm ballast resistor to add to my 2ohm coil.  Do I just put it in series between the + wires coming from the harness and the + of the coil?  There are actually two wires that attach to the + of the coil from the harness.  I was thinking I just plug that connector with two wires to my resistor, then make a wire from the other side of resistor to the coil +.  I realize this puts the resistor in play both at startup and while running, but I'm thinking its a pretty small resistor so it shouldn't hurt if I have it for both.

I ran an IGNITOR with with an 0.6 ohm coil and a 1.75 ohm ballast ressitor without any problems. I'm now using the same coil and ballast resistor with points also without issues. However, when I tried the same coil with a 0.75 ohm ballast resistor the points burned out within a few minutes.

dklawson

My goof, it was the GLC143 and not a 103. When I replaced the 998 engine with point ignition in my wife's Mini with a Metro 1275 with Lucas electronic ignition I replaced the coil with the GLC143 (Unipart) which didn't last 8,000 miles. I don't know if it failed because it was junk or burned up or what. I replaced it with the Petronix 40501 and everything seems to be running just fine. That is of course the few times I've braved the Texas heat to take it for a spin. Maybe tonight the Mrs. and I will take it out for a quick ride and get us an ice cone before heading out to watch the fireworks. Happy 4th of July y'all!

Mur... if you are reading this... how about writing a FAQ on Pertronix, electronic ignitions, and coils?

EDIT:
Geo, you can run a ballast ignition system using a Pertronix.  What you have to do differently is connect the Pertronix red wire to a switched, full 12V supply.  The black wire goes (as usual) to the coil (-) terminal.  AND you must continue to use the ballast that your ballast your car has installed.  I believe Cup Cake said he has run Pertronix units with coils rated as low as 2 Ohms without a ballast and without problems.

Mad Dog, when I searched for information on the DBL103 coil I did not come up with an electronic ignition coil, just a ballast coil.  If your Mini has OEM Lucas electronic ignition, it is supposed to use GCL143.  While that coil has low resistance and should measure similar to a ballast coil, it is my understanding that it does not use the external ballast and is only used with Lucas OEM electronic ignitions.  If you were using the DBL103 WITHOUT the external ballast on something like a Pertronix module, either the coil or the ignition module was bound to burn up. 

I had the wrong ohm coil and the engine was cutting out under load up hills in top gear. An Expert (capital E - Marcel) simply put his hand on my coil, felt that it was quite hot, and told me I had the wrong coil. So, that's my experience, but as you say, you're not running Pertronix, so your experience may be different. (Full disclosure: I had not determined ballast/non-ballast when I ordered the Pertronix and coil, so it was my fault.)

My understanding is that the igniter cares about what current is fed to it.  If you have too much, you will burn it out.  If you have a 1.5ohm coil, that doesn't mean you can't use it.  It means you can use it as long as it is ballasted so that the current is reduced.  The way you check if it is ballasted is to measure the voltage in the on position across the primary.  If it is 12V, then it is unballasted.  If it is 9 or less, then ballasted.  The current is determined by V/R.  So in my case I'm a little borderline (10V/2ohm=5 amp).  The literature I read on the petronix igniter said anything under 4amps is fine for a 4cyl car, anything under 8 is ok for a 8 cylinder car.  I don't actually have a petronix igniter, so I'm going to double check exactly what it is for mine, but I'm thinking I'm probably close enough. 

 

With Pertronix ingition, you'll want a 3-ohm coil, not a 1.5ohm one.

Actually, I think I goofed on the measurements.  The 12V I was reading was with the car running.  With the key just in the on position, I read ~10V.  Now I'm thinking I already have a ballasted setup, and the coil is the right one for the car.  10v/2ohm=5amp to the igniter, which shouldn't be too far out of range.  Anyway, I'm checking with the distributor merchant to see if I'm compatible.

 

Would like to also hear from others who have electronic ignition what type of coil they use.  Is it just the coil resistance and input voltage that affects igniter reliability, or can too much output voltage from the coil also fry the igniter.  The Petronix 40501 outputs 40k volts.  I think the 40K should only influence the HT components (rotor/cap and spark plug gap) but just want to make sure. 

When I went from point to electronic ignition I ordered the DLB103 (Unipart) coil which is suppoosed to be the coil for Mini's with eletronic ignition. That piece of junk coil didn't last a year before it left me stranded on the side of the road. I have since bought the Petronix 40501 coil which is a 3.0 Ohm coil. So far so good.

I think I might need higher resistance.  How do I add a ballast resistor, or is it cheaper just to get a higher resistor coil?

Ask the seller of the electronic distributer what coil resistance is required, 2 ohms might be too low. With the engine running the over 13v (alternator voltage) across the terminals or 12v (battery voltage) with just the ignition on has nothing to do with it.

I ordered an electronic distributor and now am wondering if my coil (Lucas DLB102) will work with the new distributor.  I measured 12V across the +/- terminals of the coil, with engine on, and 2 ohm resistance across the terminals with everything disconnected. I read somewhere that if the resistance is too low, a ballast resister would be needed.  Is that the case, and if so, how would I add the ballast resister?