<VV> Electronic Ignition Distributors

[Seth Emerson]

About 6 years ago, I worked with a company in Southern California,Top Street Performance, to adapt “their” design of a “ready-to-run” electronic distributorto the Corvair motor. It took a while to get them into production. I knowseveral folks at that company. They are mostly marketing and logistics folks.They rely on the design engineers at the distributor manufacturing company foradvice.  And I rely, somewhat, on the people at TSP. TSP sells manyproducts that parallel those made by MSD. (MSD does not make a Corvairdistributor). In fact, many of the MSD products are now made in the same “place”as the TSP products. (Not necessarily in the same factories.) Prior to workingwith TSP, I had adapted 10 of the MSD, inline-6 distributors for the Corvair,making several new parts to convert them. All of those units are still runningin race cars around the country. Those converted MSD units were what theindustry calls “Pro-Billet” units. They have no electronics inside, feeding outa magnetic pulse to one of several external ignition boxes, such as the MSD 6Aor Intellitronix box, or one of a dozen others.

The TSP unit has the electronics package internally mounted andhooks up to the coil, 12V power and ground. Very simple. This design is subjectto some external variables. The voltage fed to the power connection of thedistributor should be 12 volts in regular operation. That means bypassing thedropping resistance wire in the Corvair engine compartment harness. (All excepta few Spyders that had an external resister).  Many folks had already donethat trick to feed a Pertronix Ignitor II, which can also run on a full 12 Volts.The easy method to do this is just feed 12 volts to the coil and hook up thepower to the TSP dist at the coil. However, feeding a full 12 volts to the coilcan drastically increase the current through the coil - that the TSP distributorhas to switch, unless a higher resistance coil is used to replace the OEM coil.Worse, many of the aftermarket coils are even lower in resistance than theoriginal coil. When TSP released the Corvair distributor, they recommendedtheir low-resistance coil. It is essentially a clone of the MSD Blaster 2 coil.When MSD recommends it with their “electronic- Ready-to-run” distributors, theyrecommend adding a resistance in the coil feed to limit the current. Thisresistance isn’t needed with their external ignition boxes, because batteryvoltage is never fed directly to the coil in a “Capacitive Discharge” system.Using the MSD blaster coil – or any equivalent – will increase the currentthrough the distributor switched ignition circuit. Although that will increaseto maximum voltage that the coil can put out, it will severely shorten the lifeof the internal electronics. For a new installation, I recommend using a 3.0Ohm (Primary Resistance) coil, with the standard installation, including thebypass to feed 12 Volts. The higher Ohms rating of the coil will limit thecurrent through the circuit. There is a list of 3.0 Ohm coils at the end ofthis note. (I am sure there are others available)

If you are already running one of the internal electronics TSPdistributors and want to prolong the life of the unit, I suggest this approach.If you already have a low resistance coil – anything 1.5 Ohms or lowerqualifies in this particular instance - (An MSD Blaster 2 is rated at .7 Ohms)I suggest using the factory resistance wire to feed the coil, but split-off the12 volt feed ahead of the resistance wire (at the firewall plug), and feed thedistributor this 12 Volt feed. This way, the coil gets the higher resistancefeed, but the distributor power feed would always get full voltage. This willrequire some minor wiring changes, but it is easy to do.

When the distributor first came out, I relied on the informationfrom TSP and their coil recommendations. Shortly after the distributor cameout, TSP released their own coil. It is virtually the same as the MSD Blaster2coil (.7-Ohms). I added their coil to the list of recommended coils.  I nolonger recommend this coil, or any other low Ohm rating coil, unless additionalresistance is added in the feed circuit.  TSP has provided me withreplacement electronics packages, and they are also available on their web site.The distributor has to come apart to replace it. 

 I have swapped out more than a dozen failed units, and I willcontinue to support units in the field. It has been more than 18 months since Ihave supplied any of the TSP “ready-to-run” units. But several other companiesare supplying them. If correctly wired, they can supply a powerful, reliablesystem. TSP offers a 12 month warranty on the units.

The only distributors I now supply are the racing-orientedPro-billet units – with no electronics inside. These magnetic-pulse unitsutilize an external box and make a great integrated ignition system. If youhave any questions or concerns, or need help with your installation, drop me anote.  

 

3.0 Ohm rated coils:

- Pertronix Flamethrower Coils– Not Flamethrower 2

P/N 45001 - P/N 45011 - P/N 45111 - P/N 40611 - P/N 60130

 

- Standard Motor products P/N UC15 or P/N UC15T

 

- Comp-U-Fire P/N 30352 - P/N 30354 – P/N 30356