: Pertronix Ignitor conversion...

Swedish DeVille Dude
06-15-10, 12:54 PM
I'm just about to make a conversion from points to Pertronix Ignitor in my 1968 Cadillac DeVille. I've read a bit about it on the internet and I think I have figured out how to go about it.
One thing, though, which people seem to have different opinions about is whether you should increase the spark plug gap when using the powerful "Flamethrower"-coil (which usually comes with the Ignitor when you buy it at Ebay). Anyone who has any experience with this?

Kind regards from Stockholm, Sweden!

06-15-10, 02:03 PM
I run Pertronix distributors and/or modules in all my Olds 455 marine engine rebuilds. Very accurate and faithful.

I use either the Flamethrower chrome or ACCEL yellow coil with no problems. If your original ignition system has a ballast resistor or wire the new Pertronix will still function perfectly well.

Where the original spark gap was .035" I go to .040" and use NGK Iridium tipped plugs.

You can safely open the gap by .005" from original.

Swedish DeVille Dude
06-16-10, 04:03 AM
Thanx for the reply.
I will start the installation tonight.
I read on the Pertronix official site that you have to connect the red wire to a 12 volt ignition source before the ballast resistor (which seems to be in the shape of a wire in my car). I thought I could maybe use the wire that used to run to the air condition (which I don't use) and connect the red wire there?

After I have got it running properly I'll consider opening the spark plug gap 0.005".

Cheers from Sweden!

Swedish DeVille Dude
06-16-10, 03:01 PM
Well, the Pertronix Ignitor and the coil is now installed and it went quite easy.
Though, connecting the red wire to the air condition wire wasn't a good idea since there isn't any power at that wire while the key is turned to start.
I connected a wire directly from the battery to the red ignitor wire and the car fired right up and after a few seconds it idled smoothly.
So, I need to find a spot in the electrical system where I have 12 volts during both start and ignition position...Any ideas?

06-16-10, 06:01 PM
Normally, your ignition switch should have several positions: OFF, ACC, ON/RUN, START.

I wire my Pertronix systems to use a full 12 volts at START and revert to the ON/RUN voltage from the ballast wire when you release the spring-loaded key.

06-18-10, 12:11 AM
I installed a DUI HEI distributor, and also needed a wire with 12V when key is in START and RUN. Their instructions say you can tap into any of the fuses in the fuse box that matches that description, and they also recommend the solenoid, as long as you make sure 12V is only present in START and RUN. DUI and Pertronix may have different requirements, I am no expert. I believe certain circuits are disabled in START so they don't hog current from the starter. I chose to cut the pink wire by the ignition switch and ran that straight through the firewall. This is the same wire that is normally used for ignition. (By the way, yes, the ballast resistor *is* a wire. It is a wire that has resistance built in.) Submariner knows what he's talking about - but I did not know it was possible to continue using the ballast resistor wire once the car is started. I don't believe this was possible for my DUI distributor. Here's what DUI says on their web site:
"Your hot wire for the DUI must be at least 12 gauge and it can be connected to the starter solenoid or a fuse. The solenoid is usually
the easiest place to connect your hot wire to but make sure you use the terminal that is hot only when the key switch is in the start and
run position. Same with using a fuse, just make sure the voltage is present only in the start and run position. In most applications, we do
not recommend using the existing ignition hot wire. It may be too small or a resisted wire thus reducing the voltage. 1974 and later GM
vehicles can use the existing hot wire with the DUI as they were originally set up for HEI distributors."

Swedish DeVille Dude
06-18-10, 02:35 PM
Thanks for your replies, guys.
Well, using the the ballast resistor wire seems to decrease the voltage to 8-10 volts which isn't recommended (according to what I've read) for the Pertronix to work and the Flamethrower coil to use it's full potential.
I guess I'm looking for a fuse in the fuseblock that has 12 volts in the Run position (in the Start position the power is still being fed from the starter solenoid via the wire that goes from there to the coil, right?).
I hope to finish this installation tomorrow. I'll let you know how it turned out.
Cheers from the other side of the pond, Sweden to be more exact!

06-18-10, 02:44 PM
The ballast resistor or wire is supposed to drop the running coil voltage to 8-10 volts. That keeps the coil from overheating - a Pertronix system will run just fine when wired correctly: the START:12 volts is to supply a somewhat hotter spark at start due to cranking voltage drop - there is no reason to run the coil at full system voltage of 13.5 to 14.6 volts - that only leads to early failure of components.

Swedish DeVille Dude
06-20-10, 02:59 AM
Well, I have now finished the installation and the car started very easily. After it had warmed up I checked the timing which was now way off. Corrected it using a timing light but I find that if I place it at 5 degrees BTDC at around 550-600 rpm (according to the Shop Manual) the engine doesn't run as well and there is a big hesitation when I pull off from a complete stop, and then the car really jumps forward!
Any suggestions, guys?

06-20-10, 01:34 PM
When you were working in the distrubtor , did you make sure the weights were not stuck and the springs looked good.. Because if your centrifical advance or vacume advance are not right it will cause problems..Now the next thing that can cause problems is the stock cam timing gear..The teeth on this gear have a plastic coating... After so many years, not miles, the plastic chips and breaks off... This causes slop in the chain and sooner or later jumped timing.. In 1968 to 1973 they were small chamber heads, from 74 to 76 were large chamber heads... If the motor jumps timing with small chamber heads it bends the valves, large chamber does not bend valves... This extra slop in the chain can make it run bad when the timing seams to be set right...If you ever do change the timing set make sure you put in a good set.. Use a Cloyes 9-3139 ... These sets come with 3 timing key slots.. one for -4 degrees and one for "0" degrees and one for +4 degrees... If I was using a stock cam I would use the +4 slot....