Pertronix and plug gap?

I just read some info on another thread about plug gapping in consideration of an electronic ignition. I put new plugs in that were gapped to .025. I run Pertronix with a standard Lucas coil, I also have a Weber 45 MCHH carburetor, which is sort like half a 45DCOE. I am having a problem with the car sputtering when it gets warmed up. In other words, I start the car fine and it runs great and idles great at around 850 RPM, I take it for a run enough to warm up and when I slow down it begins to sputter when i accelerate. Could any of the above factors cause this? BTW timing is set at 18 degrees BTDC.

I've found absolutely no difference with 25 or 30 or even 25 thou gap with my Pertronix.

the sputtering is, to my mind, more likely to be a mixture transition condition than a spark plug issue

Jeff told me to gap them at 30-32 with Pertronix, didn't notice a differance however from the 25 I had them at.;)

Same experience as Mac. I gap mine a bit wider (.035) because I also have a MSD-6A installed.

It's a fuel problem, not an ignition one. There are several components, in the carburetor, that need to be calibrated properly so that they work in unison. RAY

A wider gap only helps under adverse conditions (such as starting in cold weather). Increasing the gap too much will allow the voltages to get higher than the dielectric strength of the cap or rotor.

Besides, I'm with Ray - this sounds like a fuel mixture problem.

Was there a problem before the pertronix?

I ran a wider gap for a while, but quit messing with it as the difference was negligable. Also use Pertronix' 3 Ohm coil. Best thing I ever did was get the HS4's rebuilt & run mid-grade gas. What Octane rating do you run?

Hey Ernie,

No problem before Pertronix.

Hey James,

87 octane.

If it ran better with points (before the Pertronix) then:

1) Check the timing - installing the Pertronix will alter the timing
2) Verify the Pertronix is hooked up correctly.
3) If neither of those solve the problem, revert to points and see if the problem goes away. If it does, you may have a defective Pertronix.

Hi Lew,

I had a pertonix for a year or more... then I began having problems with idle...thought for sure it was air leak or carb problems... so many things contribute to this stuff...

Anyway... eventually the pertronics died. Replaced my old points distributor and it ran great... got the pertronixs warranteed... and then... it would start fine.. as I drove (or idled in shop) and it warmed up, it would want to stall... then a little while later run ok. Never got to the bottom of this... I "suspect" a weird internal problem with the pertronixs but have reinstalled my points dizzy and haven't looked back - Yet.

For what it is worth... I think your problem is in your ignition

Ernie

Not sure why installing just the Pertronix points substitute control head would make any difference for plug gap unless you also used it to trigger some sort of high powered ignition coil/system such as the MSD, Jacobs, Flamethrower, or others that actually work to produce higher voltage sparks. In that case, yes, you should be able to open the points more, because you will have more current and perhaps voltage than a normal points + coil setup. If you have a high energy ignition system, or even a capacitive discharge system, all the Pertronix points substitutes will do is turn their voltage and current on or off, even as they do an ordinary coil. Perhaps you are using a complete Pertronix system rather than just the control head that sits in the distributor??

Keith - the other thing I did was replace the primaries 2 years ago. I had been running the original 38 year old wires (duh!) and when I was in Louisville, KY (humid!) it wouldn't start like it did in Seward, AK (30% - 40% humidity on the average). JDW suggested changing all the wires, cap & rotor and Boy Howdy! did that make a difference!
All under $30.00 @ NAPA.
I used to live in Northern Indiana just West of Ontario and if I recall, humidity is a factor there, too. Can't hurt...

I had the Petonix in my '74 roadster, and , after rebuild, noticed a little "stutter"...I suspected something in the dizzy, and changed to the Moss "super" rotor (the $11 one)...It made a real difference...Some rotors have cross-voltage in the plastic , that will mess with your ignition....This is nothing that you can see, so there's no real way to test it...I will never go back to the cheap Chinese rotors.
By the way, I'm putting the Petronix in my '73 GT, as well.
(soon as I get it back from headliner installation).