Hi John ,Specific to your tale, there might have been a larger gap between the fixed contacts and rotor tip on the aftermarket parts ,( mechanical tolerances) causing a longer arc there and so more RF noise . There should be a second capacitor from the coil + terminal to ground at the coil ( RF bypass) . This prevents radio noise from getting into the harness and + 12 . Also FYI, hood closed or open impacts it , Hood must be grounded ( usually is ) to shield rf . All the parts in the original hemi distributor stock are beautifully engineered and are often replaced for no real reason with often inferior stuff . Left alone , no problem . However once someone “pulls a plug wire” and tries to arc it to ground by hand to “ test spark” the voltage —which -with a plug connected there is under 20kv -may go to 40 kv —breaking down the cap or rotor or worst of all , the coil insulation internally . This coil breakdown can then be intermittent . a skip forever that comes and goes . If testing for spark use a tester with neon bulb or connect a plug and ground it thoroughly so unloaded volts do not jump way up . While on this , be sure coil tower is spotless and greased. Good tool to make , spark tester , a plug with attached 2 foot ground wire and clip . Even old points are fine —all will show burn marks in 1000 miles ,— normal- what matters is dwell meter reading . Dwell ok, spark energy is ok . ( with a good coil ) .
The real problems come in my experience with changing all this to , say, NAPA parts , especially the capacitor . The aluminum aftermarket can one with an X or line stamped into end of can is the bad one . But any with a rubber cone around exit wire are suspect . I took two apart , after much grief , the rubber cone is used as a push spring to press the aluminum foil of the capacitor winding against the aluminum can end . That is the only connection develops . Aluminum forms aluminum oxide , an insulator —over a period of months to years . Soon an intermittent connection . In mine , visible evidence of arcing happening there , every single burn spot through oxide reflects multiple episodes of weak spark . With no capacitor in circuit , kv drops drastically from strong 20-30 to maybe 5 . That means hard starting high speed miss etc and you think it is carbs , plugs , wires or points etc . And comes and goes (!!!) Drives you crazy .—-
once I knew this ,I bought a bunch of e bay NOS mopar caps , with the copper straps . Can’t do this !! Old Mopar Caps rarely bad ,well made, easy to test with analog ohmmeter ( digital useless) . Do not change unless really definitively bad. Had same issue with same cap on Kohler RV generator . Sometimes no start. Other times fine. “ Can find nothing wrong” I even have replaced them with epoxy sealed radio caps ( EE hat on) Panasonic .27 uF about 1 kv ) . Japanese quality , Panasonic only. same issues with junk cap parts on market . Note that putting in another junk rubber cone cap will fix it — for a while !!!
Also Note that Pertronix will also fix the problem you may have brought on yourself . the original stuff is great ! As designed . Set the records. So, one chooses between check dwell every 10 k miles or “no maintenance” . However you also choose fix at side of road in ten minutes points) or tow/ you walk with electronic . ( happens a lot) personally , as EE I think RF from plug wires has nothing to do with dead silicon device failures . Would still work when interference goes away . Instead , Heat and stress kill silicon transistors . Lack of heat sink. Wire story sounds like pass the buck . Just sayin . But also very true should be resistor wires in a street car. Sent from my iPhone not by choice On this same topic, had a 57 C with nice sounding radio and HiWay HiFi until I changed cap, rotor, points, condenser. Did not change plugs or plug wires, but had a lot of ignition noise after replacing the parts in/on distributor. I put back the original cap and rotor and 90% of the ignition noise went away, but not back to the quiet it was before I started. I did have to 'pull' the wires out of the old cap to put on the new, and then 'pull' on them again to go back to original. Did I cause that 10% problem by moving the wires twice? Why so much additional noise with new cap and rotor? (from Rock Auto- parts labeled made in Mexico and USA, not China)
i thought the original 57 at least wires were resistor wires ? carbon type ? actually ok if not pulled on ? i say that as way back , I had misguided idea ( from an “ expert” ) that copper was better and I made a set of Packard 440 wire ( copper ) for my 392 using the beautiful early hemi white porcelain insulators . then the question of resistor plugs or not ? the thinking at the time was the “ wires lost power , a step back “ but today we know they are about 20 k ohms ( varies) and with 20 kv an amp can flow . ignition corrects are in 50 milliamperes range ,so ohm drop is not an issue .Carbon wires are more effective at RFI reduction than a spiral .. But can break .. easy test with ohmmeter . A hemi with copper wires was probably a period “ upgrade” —- like I did . that said , = good info re pertronix . i have in general kept points . The 300 records were all set with points . And — yes, they are difficult to set , have to have a dwell meter imho . But then ok for 10-20 k miles . easy to check in a minute with dwell meter Problems today in my experience are more likely the junk chinese capacitors with black rubber cone and black wire . So, save the mopar ones with copper strap . they are almost never bad. interesting thing .... thank you Ray Sent from my iPhone not by choice
Hello Group -
During restoration of my late father's 1957 300C, I installed a
Pertronix Ignitor II electronic conversion kit (no more
miserable-to-adjust points in the inaccessible distributor!) along
with their "Blaster" 0.6 Ohm 45kV coil. Pertronix instructions
say their unit wants a steady 12 volts, not the reduced voltage
from the ballast resistor, so I just filled in the backside of the
original ceramic ballast resistor with solder (no a NO-resistance
resistor!) so it gets constant 12 volts while maintaining
completely stock appearance. I also wanted to use modern
stainless steel spiral-wrapped plug wires for RFI suppression to
get best sound from the radio and Highway Hi-Fi; I had to have
those specially made because those wires are not ordinarily
supplied in the original black color and 7mm size to fit into the
long spark plug connectors (but there are lots of 8, 9, 10mm
diameter SS-spiral-wrapped wires available in gaudy red, blue,
yellow, etc.). The new setup looks perfectly stock and works
very well, especially when coupled with modern fine-wire
Iridium-electrode spark plugs (long life and foul-resistant) -
usually starts within 1/2 second! The starting and running have
been quite reliable for the last two years.
HOWEVER, It turns out that my combination of ignition components
may have been serendipitous....... I just now talked with
the Pertronix Corporation about an application for one of my
Porsches, and learned some startling information about their
products, which may have great impact on the reliability of the
conversion! It turns out that the Pertronix kit is NOT electrically compatible
with the usual copper-core plug wires we are accustomed to; the
representative cautioned me that their unit will usually fail
within two years or less because the RF interference from
copper-core wires will FRY the electronics!! That plug-wire
incompatibility is NOT mentioned in their installation
instructions - Maybe that is why we have long heard about spotty
reliability from the Pertronix conversions! I told the rep that
the failure to highlight that admonition regarding plug wires in
their instruction was a major oversight on their part and was
probably hurting their reputation because of reliability
experiences. He agreed and said he would forward that
recommendation to upper management.
BOTTOM LINE: The Pertronix factory says: DO NOT USE the usual
copper-core wires with any Pertronix conversion unit!! I had my
special-order black 7mm RFI-suppressed bulk plug wire made by
Kingsborne Wire Werks (www.kingsborne.com) 800-642-0375, and
also bought their distributor-end terminals to fabricate my own
set of custom-length plug wires. They were reasonably priced
with quick turnaround.
Ray Melton Las Cruces, NM
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Posted by: John Grady <jkg@xxxxxxxxxxxxxxxxx>
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