Spark Plug Spark Question/Problem?

CobraSix

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Currently I'm running Pertronix in a 68 Dizzy, vac hooked up to carb. MSD Digital 6+ through a Petronix Flamethrower coil.

Okay...starting yesterday, my car would intermittently have a very bad hesitation. Like a cylinder not firing. It didn't happen consistently until this afternoon. When it happens, it is definitely a steady miss, so I figured it was one cylinder missing. The miss is rythmic and dependent on engine speed, not load (though under load, it is more noticable that something isn't firing)

So when I get home, I check for spark by pulling a wire off one at a time. All have a nice strong park if I hold the wire about 1/4-1/3" away. not bad being that the boot cover is comes down about 1/2" or so. All fire nicely except #2 cylinder. At first I figure it was dead. No spark at all. So I swap wires with #1 cylinder (the entire wire, not just the plug end). Still no spark. So I take the pertronix and rotate it so a different magnet should be tripping the sensor for #2. Still no spark. That is until I go to put the plug end back on and I can hear it arcing across, but not until the plug end is almost completely on. Not like any of the other wires. I pulled plugs yesterday, but didn't find too much stuff, but #2 had a little build up.

So, is the non-strong spark a probably cause of my misfiring? It is extremely rythmic, and dependent on engine speed for it's frequency. If the weak spark is the cause, where do I look? Is it my cap? The cap looked fine, and so does the rotor. both less with 1 year old. I guess I could put the points back in and see.

Maybe it is time I just finish my conversion to DS2.

Thanks.

Slade
 
I guess I'm just going to go ahead and swap to DS2 tomorrow morning. All I need is the cap, adaptor, rotor, and wires. Might as well do it since i have to replace the cap.

Slade
 
You will notice a difference when you install the DSII...
I ran the petronix setup prior, but was surprised how well the DSII runs with the MSD box... get the Ford adapter and run that... it was the easiest in wiring the thing... simple plug and play.

but I had a much more even power curve with the DSII... more mid-range and a smoother accel... it was the best under $100.00 mod I have done.
 
Take your DVM and check for continuity through the plug. I had the same problem once and found that the brand new plug had a very high resistance reading.

Good luck, Ric.
 
CorbaSix,
Have you checked for a vacum leak on the intake around your carb's? I have found it to be very easy to get a leak, just enough that it diesn't fire at low rpm but then fires at higher rpms, much like you discribed!
 
It turned out to be a bad cap. #2 wasn't getting a good spark. Switched to DS2 since I was doing a basic tune up. Problem is all set.

Vacuum leak was the first thing I looked for though.

Slade
 
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