Pertronix ignition upgrade - Experiences? Reccommend or not?

[TroutMD]

I am thinking of upgrading my 72 280SE 4.5 to a Pertronix ignition (Part ref 1885)

Curious what other members who have done this upgrade think. Worth it? Would you recommend it or not? If so, what were the most noticable improvements or issues after the fact?

Also, I read somewhere that you have to be careful leaving key in position 2 after upgrade - Is this true?

Thanks in advance for any insights.

[97 SL320]

Get a hold of the guy in this thread.

http://www.peachparts.com/shopforum/vintage-mercedes/378150-w108-question.html

[Mike D]

Running my '74 280C on one. No problems so far.

Two things to be aware of.

Yes, you should not leave the key in the "run" position if the engine is not running. If the igniter happens to be in the "on" position in relation to the distributor cam lobes it will overheat and possibly damage the switch/trigger gear.

The same thing can happen if you "jump start" your engine or use a battery charger to "boost" starting voltage. Personal experience.

It is usually not a permanent fault and the igniter seems to recover after the module cools down.

Pertronix recommends suppressor plug wires and your car has solid core with a resistor on the plug end. I converted mine but other members have used their existing wires with no problems. YMMV.

[Graham]

Above is all correct.

I have had a Pertronix 1885 in my 350SL 4.5L djet for about 8 years. Never any problem. Only used to replace points so far.

The issue with leaving key in run position is true, but it is an unusual situation. If you do it knowingly, just disconnect the red lead. Changing to a Pertonix II apparently overcomes this problem, but then you need to make other changes such as suppressed plug wires which moves you further into non OE territory. Some have apparently done this, but not a great deal of experience recorded.

A Pertronix can just replace the points, or it can replace the points and the ignition module (MB call it switchgear). As a points replacement, it really doesn't do much more than eliminate need to set points gap/dwell. But it is more forgiving of distributor shaft wear/wobble.

The 1885 will work fine with copper core plug wires that are standard on our cars.

If you bypass the switchgear, you should also change the coil. But no need if switchgear is still working.

This link provides wiring diagrams (Ones that came with my Pertronix were generic and not much help)

http://www.benzworld.org/forums/r-c107-sl-slc-class/1714668-pertronix-install-without-switchgear.html

Definitely a good upgrade.

[vandor]

I installed the Pertronix ignitor on my '72 about 3 years ago. I bypassed the ignition module and connected it straight to the coil. The coil turned out to be the wrong one and the car had no power at higher throttle settings. I replced it with a Pertronix coil and all has been well since.

[JMela]

Recommend highly. You'll notice a real difference for relatively short $$.

[Tony H]

My coupe ran poorly when I bought it. It would miss badly when cold and at high RPM. The seller let it warm up for 20 min before he let me drive it-trying to hide the condition. The PO had obviously put lots of parts on it trying to fix it. I cleaned the trigger points and installed a Pertronix ignitor with their coil and it was like a whole different car.

[TroutMD]

Thanks guys. I went ahaed with the install this week, and my reaction: WOW. It is like a completely different car. Starts in an instant, idle is much smoother and runs cleaner and leaner.

Definitely worth every penny.

[fever]

I have run the Pertronix II along with Flamethrower II coil for two years in my 71 280SE 3.5. It has been fantastic with one exception. My RPMs read ~3 times the actual number at idle. Any thoughts on how to correct this?

[Graham]

Originally Posted by fever

I have run the Pertronix II along with Flamethrower II coil for two years in my 71 280SE 3.5. It has been fantastic with one exception. My RPMs read ~3 times the actual number at idle. Any thoughts on how to correct this?

The Pert II is not usually recommended for our cars. This because they say it is not suitable for cars with solid core copper ignition wires. Did you change the wires on your car?

Regarding the tach, that happens if the existing switchgear is bypassed. The incorrect reading can usually be corrected by installing a resistor in the tach wire (green with black stripe). 8kohm 1/2 watt resistor should work. Installing a potentiometer on a temporary basis may help determine the optimum resistance. (This works with Pert I - no experience with Pert II)

[fever]

Resurrecting an old thread. Finally, after years of fixing various items I found the problem on this. Number one it needed the proper resistors in between the setup after the bypass. Pertronix now provides these instructions. Number two, after replacing the alternator with a 60w for a little more juice I was still having intermittent charging issues. We took out the voltage regulator (original alternator has the voltage regulator built in) and it fell apart as we uninstalled. Installed a new voltage regulator and now the 3.5 is turbine smooth. Not quite inline six BMW but incredible.

Goes to full redline and rpms read perfectly. Second gear lays down a half second scratch. Full power.

[fever]

Just wanted to add I went with Pertronix II and Ignitor coil for maximum spark.

[Graham]

Originally Posted by fever

Just wanted to add I went with Pertronix II and Ignitor coil for maximum spark.

Still interested to know if you used original copper cored type ignition wires or changed. This because Pertronix say to not use copper cored wires with Pert II.
With the Pert i Ignitor, we just used original wires.

[fever]

Originally Posted by Graham

Still interested to know if you used original copper cored type ignition wires or changed. This because Pertronix say to not use copper cored wires with Pert II.
With the Pert i Ignitor, we just used original wires.

I had all of the wires and plugs changed a few years ago and was told they are not solid core. Car is in the shop now getting a new slave cylinder and some other attention. I'll find out and let you know.

[napster]

Originally Posted by fever

Just wanted to add I went with Pertronix II and Ignitor coil for maximum spark.

How did you get the tach to work correctly.

Thanks.