Electronic ignition choice[s]

[Dono]

New Years Greetings from MT,
I have a '65 TR4, and rebuilding a 71 Spitfire. I want to put electronic ignition on both. Recommendations / suggestions?

Thanks much! Don L.

 

[prb51]

Many pertronix fans here, I've an MSD6 with points...crane etc...

 

[tdskip]

Hi Don - +1 on Pertronix, just make sure you get the correct coil for it and don't leave the ignition switch on.

 

[TR3driver]

I ran a MSD6 with points on my TR3A for many years. Had a "teething" problem a few months after initial installation, where it literally burned away the RFI suppression resistor in the cap (along with some of the cap itself), and then burned a carbon track through the coil tower. But I was able to limp home by fabricating a replacement center contact from a paper clip. Carved a non-resistor contact from the center of a flashlight battery, new cap & coil; and it ran great for many years. Module died once, but the factory sold me a 'reconditioned' replacement at a reasonable price.

But I was worried about all the spark scatter I could see with my timing light (which in retrospect may or may not have been "real"), so I eventually switched to a Crane XR3000 (and moved the MSD to another car).

The XR3000 was a royal pain to install properly, but worked reasonably well once I finally figured out that my rotor was hitting the pickup and causing problems; plus I had to modify the bracket to get things to fit right. Well, except that time the ground connection got corroded and the unit just quit working, while driving home at night in the rain. And the engine just never did seem to run quite as well with the Crane. Started great, just kind of sluggish at part throttle & mid rpm, compared to either points or the MSD. Anyway, I won't be buying another XR3000.

This time around, I'm going for a Pertronix. (Just installed it Sunday night in fact, but haven't taken a test drive yet.) When the "hot rod" motor is completed, I'll likely add a MSD box again, see what difference it makes.

 

[70herald]

I have a crane XR700 on my Herald. I choose it over the pertronix partly because I was told that Pertronix does not like covering warantee issues for overseas buyers. The other reason is that the crane shuts it self off if the engine isn't running unlike the pertronix.
Started up first time and seems to work just fine.

 

[MGTF1250Dave]

Aloha Don,

I have a Pertronix in my TR3A and am pleased with it. The car also has the original distributor manufactured in 1958. I had it rebuilt by Jeff at Advanced Distributors because of badly worn shafts and bushings. I noticed how bad the wear was while trying to set the points gap and discovered I could open and close them by pushing against the rotor. The point of my story is, make sure the distributor is in good working condition because any electronic ignition will only work as well as the distributor it installed in. The one advantage of Pertronix over points is the gap doesn't need to be checked and reset periodically.

Pertronix units are specific to the either positive or negative ground so match it to your car's electrical system. If you decide to replace your coil make sure you get the same type, either external reistor or internal resistor.

 

[TR6BILL]

The Crane XR3000 is the only unit that you can leave the ignition key on without the engine running and not have the unit burn out. For what it is worth.

 

[TR3driver]

The Crane XR3000 is the only unit that you can leave the ignition key on without the engine running and not have the unit burn out.

I disagree, Bill. The later XR700 (with the LED on the box) is also safe; as are the MSD units. In both cases the power portion of the unit shuts down when the engine is not turning.

A Pertronix used to trigger a MSD should also be safe, since the current through the Pertronix module will be much less than when it controls the coil directly.

I have also inadvertently left the Lumenition on my Stag on for several hours, with no ill effects to the ignition module. Lumenition offers no caution against this, nor does Crane (even for the early XR700).

To the best of my knowledge, only Pertronix cautions against leaving the key on.

 

[Mark Jones]

I have used both the Pertronix and the Crane XR700 in my Spitfire and I prefer the Crane over the Pertronix. I found the engine ran much smoother with the Crane compared to the Pertronix and the LED on the Crane's ignition module makes it so easy to statically time the ignition system.

I do carry the Pertornix as a back up (my Spitfire originally had the OPUS electronic ignition unit which failed just a couple years ago).

 

[KSIS]

I have run a XR700 in my 72 MG and an older Allison in my 64 Spit. I was happy with both. Ran a petronix in my 62 Bug seemed to sputter and miss. Ran a MSDS in a 65 Mustang, idled nice but would miss at high RPMs.
I likes the allisons.... easy install, quick starts, smooth idle and smooth acceleration.

 

[SkinnedKnuckles]

I ran the Crane XR700 for several years then upgraded to the XR3000 5 or so years ago as it's capacitive discharge. This allowed the plug gaps to be opened up to around 0.04". Never has any trouble with either. Way back then Pertronix had alot of problems with the sensing units which scared me off.

 

[TR6BILL]

The Crane XR3000 is the only unit that you can leave the ignition key on without the engine running and not have the unit burn out.

I disagree, Bill. The later XR700 (with the LED on the box) is also safe; as are the MSD units. In both cases the power portion of the unit shuts down when the engine is not turning.

A Pertronix used to trigger a MSD should also be safe, since the current through the Pertronix module will be much less than when it controls the coil directly.

I have also inadvertently left the Lumenition on my Stag on for several hours, with no ill effects to the ignition module. Lumenition offers no caution against this, nor does Crane (even for the early XR700).

To the best of my knowledge, only Pertronix cautions against leaving the key on.

Years ago, when I ran an early Crane XR700 on my first TR6, I burned out three units. Finally, an engineer at Crane sheepishly admitted this would happen by leaving the key on. He told me at the time that the 3000 unit was internally protected against that. They must've changed, as you said.

 

[70herald]

Years ago, when I ran an early Crane XR700 on my first TR6, I burned out three units. Finally, an engineer at Crane sheepishly admitted this would happen by leaving the key on. He told me at the time that the 3000 unit was internally protected against that. They must've changed, as you said.

The XR700's with an LED are internally protected. They are the latest version of the Crane / Alison unit. the older ones were not and of course burned out like yours did. Of course Crane learned and modified the design something which Pertronix hasn't done yet.

 

[prb51]

I ran a MSD6 with points on my TR3A for many years. Had a "teething" problem a few months after initial installation, where it literally burned away the RFI suppression resistor in the cap (along with some of the cap itself), and then burned a carbon track through the coil tower. But I was able to limp home by fabricating a replacement center contact from a paper clip. Carved a non-resistor contact from the center of a flashlight battery, new cap & coil; and it ran great for many years. Module died once, but the factory sold me a 'reconditioned' replacement at a reasonable price.

I've had great experiences with MSD6/pts in two diff '50's era cars Randall. never burned any rotors or caps and the points lasted forever...changed them out at 10k when I figured the spring was tired.
I know you are a mechanic so what do you attribute the prob too...a bad box?

 

[TR3driver]

I've had great experiences with MSD6/pts in two diff '50's era cars Randall. never burned any rotors or caps and the points lasted forever...changed them out at 10k when I figured the spring was tired.
I know you are a mechanic so what do you attribute the prob too...a bad box?

The Lucas distributors used on the TR2-4 use a resistor for the center contact in the distributor cap. I believe that resistor is simply incapable of handling the higher spark current caused by the MSD. It was literally burned nearly white (showing just how little carbon was actually in it).

The MSD 6 produces such high voltage that a spark WILL happen, wherever the shortest path to ground is. Hence when the resistor quit conducting, the voltage simply went high enough to drive the spark around the resistor, which in turn eroded the center tower of the distributor cap (the part that normally supports the movable button). Once the gap there was large enough, the spark started jumping from the center terminal of the coil to one of the side terminals; which eventually burned it's way through the coil tower to form a more direct carbon path.

I was able to see some of this, as I did pull over several times to investigate why the engine was running poorly. When it would not run at all, I could crank the engine and see the spark jumping through the coil tower to the side terminal! Fortunately, my paper clip substitute for the center terminal on the distributor cap made that a shorter path, so was able to get me home.

So, I don't believe any component was actually defective, just the stock cap cannot handle the high spark current produced by the MSD 6. But honestly I didn't try burning up another cap, so maybe there was a problem with the old one. Certainly nothing wrong with the MSD box, as it continued to work fine with the new coil & cap.

I've seen similar problems on other cars; for example I had a MSD 6 on a Plymouth slant-6 for awhile that apparently had a bad connection between the coil wire & dizzy cap. The spark started jumping from the conductor to the cap terminal and eventually eroded the cap until the wire simply fell out! The bad connection also explained why that engine did not like rainy weather (which was why I put the MSD on in the first place).

 

[swift6]

The XR700's with an LED are internally protected. They are the latest version of the Crane / Alison unit. the older ones were not and of course burned out like yours did. Of course Crane learned and modified the design something which Pertronix hasn't done yet.

I must be super lucky. I once left my ignition switch on overnight. This happened a few years ago so my Pertronix had been performing flawlessly for about 6 years at that point. I had heard all the horror stories about leaving the ignition on for as little as five minutes with a pertronix, as well as the factory reccomendation against it. I realized that the key had been left on overnight when I got in to start the car the next morning. I figured I had nothing to lose so I twisted the key that slight little bit from "on" to "start" and the engine roared to life. No issues at all. Still have the same Pertronix in there and its still working just fine.

BTW, I realize this is anecdotal and appears not to be the general experience.

 

[TR3driver]

BTW, I realize this is anecdotal and appears not to be the general experience.

I think there is a certain element of chance involved. For example, if the engine happens to stop with the virtual points open, then there is no current to overheat the Pertronix module. Since your battery was not run flat, I'd guess this was the case in your example.

It probably also depends on how good the thermal connection between the module and the mounting plate is, as the mounting plate can also help dissipate the heat. I added some heat sink compound to the joint, in hopes that it would help (since I'm almost certain to leave the key on eventually).

 

[swift6]

BTW, I realize this is anecdotal and appears not to be the general experience.

I think there is a certain element of chance involved. For example, if the engine happens to stop with the virtual points open, then there is no current to overheat the Pertronix module. Since your battery was not run flat, I'd guess this was the case in your example.

It probably also depends on how good the thermal connection between the module and the mounting plate is, as the mounting plate can also help dissipate the heat. I added some heat sink compound to the joint, in hopes that it would help (since I'm almost certain to leave the key on eventually).

I added the anecdotal part because it seems that the overwhelming opinion amongst British Car owners is negative towards Pertronix. That mine has performed flawlessly, it seems to be in the minority. I've left the key on for extended periods several times, only once overnight. The only time I have had a current draw with the ignition on but engine not running was when I was using the Jacob's Electronics Ignition system (very much like an MSD box, but more expandable).