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Discussion Starter #1
I have a 1966 Mustang with a 289 CI 2V, stock and in excellent condition. I installed an Ignitor, Pertronix and their 40,000-v coil about 2-3 years ago. The miss-fire accrues from idle through high RPM. I have changed sparkplugs and wires, distributor cap and rotor, as well as fuel filter, coil and checked the voltage to the coil (8 volts). I also performed a compression check looking for a leaky valve; compression ranged from 158 – 163, no problems here! I have not removed the Ignitor system and installed the standard points, Pertronix tells me that the Ignitor unit either works or doesn’t.

SORRY….I also forgot to mention that I removed the resistor wire and hooked the coil directly to the battery!

Any ideas?

[email protected]
 

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Perhaps searching the archives using Pertronix as a keyword can unravel the mystery. I've seen numerous posts about intermittent ignition problems with the unit in my 3 years here.

Take a peek and maybe you'll get some tips...re-installing the points is one sure-fire diagnostic.....oh, and make sure the Pertronix is getting 12 volts...

Good luck!
 

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Yes, definately hook it up to a 12 volt supply. I spoke with Petronix tech. He told me that the Flamethrower coil will work with a resistor, but if you do have a resistor and you have a misfire, disconnect the resistor and run it on 12 volt.
 

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I had the same problem with my Pertronix a while back. I thought the unit was going bad as when I replaced it with points, my car would run fine. It turns out the 'gap' between the unit and the rotor shaft?! was a little wide. I setup mine as close as possible without touching and now it runs just fine.
 
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Discussion Starter #6
SORRY….I also forgot to mention that I removed the resistor wire and hooked the coil directly to the battery!
 
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I will try to reduce the gap, mine looks wide also, almost a 1/16".
 

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IIRC, the gap should be 0.030".
 

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If the coil is hooked directly to the battery then it's receiving power all the time isn't it? If so, might it be overheating and intermittently shorting out? Just a thought, good luck.
 
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Discussion Starter #10
The hook up to the battery was only temp, for diagnosis! Didn't change, still a miss.
 

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Have you put a vacuum guage on it yet?
 

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When did it start misfiring, how does it misfire? Does it seem to miss on the same beat every time or is it sporadic? If its sporadic I would say replace the coil and or coil wire. You may have a short somewhere. Yes also do check the gap on the points. Are you getting buildup on the rotor?
Brent
 
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Started missing a few weeks ago. I have not checked the vacuum; have changed the coil and wire. The miss is sporadic, not like that of a bad plug.
 

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Discussion Starter #15
Thanks, I’ll give the vacuum test a try. I may have a sticky valve. Come to think of it, I started to notice the roughness in the idle a short time after I changed to Valvoline MAXLife 20W50. Didn’t have a miss prior to this. Also the oil pressure gage does not show pressure for about 15 – 20 seconds after a cold engine start-up, once it is up the needle it goes about 1/16” past center. Could this oil be a contributing factor?
 

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Probably not, just coincidentel. The delay is probably a weak or sticky sending unit. Try a little Marval Mystery Oil in the oil and gas, it could help clean things up.
 
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Discussion Starter #17
I just checked the timing, OK: reset the carburetor, OK; checked the voltage (tried 12 volts directly) and the clearance setting of the Pertronix Ignitor, OK; all of this resulted in very little change, still have a miss. SO…I drained a Qt of oil and added a Qt of Marvel Mystery Oil. I should know more after I drive the car to a show in the morning. I sure hope the oil works! I plan on doing the vacuum test in the next few days, I’ll report back.
 
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