Pertronix install GONE BAD !!

Brad Roberts · 07-24-2002, 01:05 AM

A buddy of mine who owns a certain Black 74 2.0 (who also happens to be leading the SCCA SF Region CSP autoX points series) decided awhile back to install his own Pertronix ignition after his tach failed and the MSD fried his first Pertronix installed by our shop.

He left our shop this evening (midnight or so) and returned about 15 minutes later with a car popping and backfiring out the exhaust. This only happened when you came off idle slowly. I knew it was ignition related and timing related. We went through the normal checks and found nothing. I popped his cap and rotor off and noticed that the wires for his Pertronix where extremely tight. I pulled the vacuum hose off the throttle body and applied a suction to the hose and watched the vacuum plate move and stretch the wires. I told him to give the wires some room to move. He pulled out some long needle nose pliers and started to move them around. I told him to be careful not to stretch them but to actually move them in the holder. Anyway... he broke one of the wires internally. He removed the dizzy and slapped in yet a third Pertronix unit. I examined his second (which was causing the backfiring problem) and found the signal wire for the coil had a rub mark in it where the vacuum plate was rubbing it causing a short. This explained the off idle problem. As soon as you come off idle the plate was moving and grouding out causing the backfiring. It would stumble and the plate would see vacuum for a second and then ground again repeating the backfiring until we moved the throttle.

Here is pic. Please becareful when your trying these installs at home.

Va914 · 07-24-2002, 03:52 AM

Sorry to hear about the bad luck.

When I did my install I thought it was a bad design to leave the wires loose like that. I just tucked them down and am STILL hoping for the best.

I guess I shoud keep a set of the old points and condenser in the boot.

Later
Kerry

Rouser · Rouser's Garage

Like I've said in the past, "... when installed properly, the Pertronix unit will provide many point-less miles ..." There has to be some level of patience and common sense applied whenever installing any electrical/electronic device in an environment like an engine, engine component, or engine bay. The same rule applies when installing stereos and electrical gadgets of any sort.

Hey, I'm not trying to insult anyone's intelligence here; I believe 914 (and early Porsches, for that matter) owners are some of the most resourceful people out there. But you gotta pay attention to the details, even if they are/aren't all spelled out in the installation instructions.

Details … it's always in the details.

Brad Roberts · 07-24-2002, 01:49 PM

I think sometimes you have to beat it into people.

The only reason I post this drivel is to show people what mistakes can be made by the home wrench.

You should see the size of his muffler after backfiring that bad boy a few times.. LOL

Thank God he is a GREAT driver... his detail is lacking..lol

B