Long Post!
I wanted to revive an old post regarding my Pertronix setup. I am very pleased with how my car is now performing with this setup and wanted to share my history.
When I bought my car, it had the Pertronix installed, along with the original MB Ignition system still hooked in.
I am now running the Pertronix with a Bosch Blue Coil with NO ballast resistors. Have run this setup now for approx 1000 miles and my plugs have a nice brown/gray color and I seem to have little to no "spitting" out of the tail pipes anymore. Car is running great at all speeds!
See history below:
I did the following test, per the Pertronix website:
To determine if your systems coil is compatible with the Pertronix Ignitor, some measurements should be taken prior to installation of the Ignitor. Caution… While performing this test, never leave the ignition switch on for more than 30 seconds at a time.
1. Set your voltmeter to a 15 or 20-volt scale. Attach an 18 or 20 AWG jumper wire from the negative coil terminal to an engine ground. Attach positive (red) lead of your voltmeter to the positive side of the coil, and the negative (black) lead to an engine ground. Turn the ignition switch to the run position. Now read the voltage at the positive coil terminal. Turn the ignition switch off. If the voltage measured is approximately 12 volts, no resistance wire is present. A typical resistance wire will provide 9 - 6 volts.
2. The next step is to determine the resistance in the primary ignition. Label the wires attached to the coil terminals and note their appropriate location. Make sure that the ignition switch is off and disconnect all wires from the coil. Adjust your meter to the lowest ? ohm scale. If you are using an analog style meter make sure to zero the needle. Measure from the negative terminal to the positive terminal. Write your measurement down.
Now the maximum system amperage can be determined, divide your voltage measurement by your coil resistance measurement. This will give you the system current or amperage.
Four cylinder engines should not exceed 4 amps. Six and eight cylinder engines should not exceed 8.5 amps. If the total amperage in your system is higher than the amount recommended for your application, you should install a ballast resistor.
1. Example Voltage 12
2. Resistance 1.5
3. Total Amperage 8 (12 / 1.5)
NOTE: Total amperage 8 (this number must not exceed 8.5 !)
My reading was initially as follows (with MB Electronic Ignition):
1. Voltage 3.48
2. Resistance 0.8
3. Total Amperage 4.35 (3.48/0.
I then removed the MB electronic ignition and the 0.4 ohm ballast. Installed the 0.6 ballast in it’s place
The reading was then:
1. Voltage 4.80
2. Resistance 0.8
3. Total Amperage 6.0 (4.80/0.
On March 25, 2006, I removed my Bosch ignition coil (silver in color with a red label) and replaced it with a new Bosch “Blue” coil, pn 0-221-119-027-740 (thanks Dennis!). I also removed the 0.6 ohm ballast. So in summary, am using blue coil and no ballast resistors at all.
My reading is now:
1. Voltage 11.92
2. Resistance 3.3
3. Total Amperage 3.61 (11.92/3.3)
Also note: I am using Bosch Spark Plugs W7DC (default gap out of the box = .032). I Increased the gap by +.006, as per Pertronix suggestion.
bpossel (Memphis, TN.)
'71 280SL / '97 E320