Ignition Issues (cont.)

[Laldog]

I finally had an hour of quality time with my coupe to try and iron out my ignition issues.

With a new coil, Pertronix and the ballast resistor taken out, I wasn't quite sure I had things wired up correctly.

The engine would "catch", but definitely stumble and barely grumble.

Thanks in large part to the advice of MMercury and 61Porsche, a quick turn of the distributor yielded much better results. I haven't fine tuned it with a timing light yet, but things are definitely looking up.

My question is:

The distributor was definitely locked down and the nuts had to be loosened before I could spin the distributor. So what changed the timing to cause the engine to be so "off"?

 

[sfdon]

6 things in a heart beat....

Bad retard vacuum hose
Bad advance vacuum hose
Bad advance springs
Failing cam fork or distributor drive
cam gear/chain skipped a tooth
Torn diaphragm in the vacuum box

Set your engine to TDC at the dampener, the cam gear, the flywheel and the rotor.
Check to see if the rotor is sloppy.

 

[jmackro]

If I understand you correctly, the car was running OK with points. Without loosening the distributor (e.g., without changing its timing) you took out the points and installed a Pertronix. Then you found you needed to change the timing to get it to run OK again. Am I getting it right?

If so, the reason is simply that the Pertronix isn't phased exactly the same way that the points were. The Pertronix interrupts current to the coil a few degrees before/after where the points were opening. That's why you need to re-adjust the timing after making the swap.

In an ideal world, Pertronix could engineer their device and its mounting bracket so that it behaved exactly as the points had. But variations in point dwell, and the compromises involved in fitting the Pertronix module into a distributor designed for points makes that impossible.