[Trailboss71]

I've got a 55 chevy belonging to a friend.For some reason he changed the ignition switch?Don't know why.Since ,no spark.They got the car running by jumping power to the + side of the coil.Then it just stopped running.I tested the coil ,it was shorted out.Replaced it with an msd coil.I put a test light from the - side to ground got a real weak light no blink so replaced the pertronix unit,bright light and blinking.Still no fire.Any help?

[red65mustang]

test the new coil primary and secondary ohms resistance against the msd published spec's for that exact coil per attached...
and test the ohms resistance in the coil wire...

hard to tell from your info but:
it is possible the old pertronix was not getting a good ground source thru the mount screw is why the test light was dimmer,,,but it was working and will fire the coil down to about 8V minumum input to the module itself...

so do confirm there is 12V at the module on the red wire...

(a worn starter and low battery/bad cables can pull down the volts below 8 at the module=no spark because there is not enough volts to turn on the module itself)

[hp246]

Which Pertronix series?

[Trailboss71]

Thanks red,I found an older post that gave me some additional info.I tested the original coil,the replacement coil,and a really old coil that I found under the bench.All three tested good.The first was cracked and leaking oil,so I know when it gets hot it stops working.What I did finally was drop in a swap meet dual point and resister.Fired right up.Just don't understand the pertronix not working.

[hp246]

TrailBoss, He may have burned out the Pertronix unit while installing the new switch. The early Pertronix units had a tendency to burn out if the ignition was left in the on position for a prolonged period of time without starting the car. I believe they corrected the problem with the Pertronix II,

[red65mustang]

weekends miles only,,, mild motor hwy cruiser,,,points are fine (with a .034 plug gap)

at idle you want to see just 6-9V at the coil for decent points life span to prove there is enough resistance in the circuit for whatever the idle initial V supply actually is (13.4 to 14.4V)

when the rpms go up the alt amps output overpowers the circuit resistance and the coil does operate with approx 11V+,,,points are now moving fast enough that arcing is not a problem....

PS:ANY 5V solid state operating device (like a pertronix) has to have a rock solid overkill electric ground source supply connection...it's operating at such a low V potential that the slightest bit of added resistance will drive it nuts...
(copper wire ground direct to batt neg is best)

ya should have tested with a jumper from the pertonix base mount screw direct to the batt neg post,,,to know there is adaquate constant supply available...

slim chance to none but the module gap to the magnets could have been changing due to the cent plate????

picking up the electricity thru "only" the dist cent plate is not a rock solid simplest circuit...
(many oem point's dist had a ground wire points base to the motor)

my $.02:
it is so worth the effort of learning how to deal with troubleshooting SS ign (it's not rocket science),,,there are so many actual spark event performance improvements by using it...
EX: points only induces about 250V in the coil,,,SS can induce 400V to convert to Kv and wicked milli-amp "heat" so there is always lots of "reserve" spark capability for poor cylinder conditions...

PPS: ign on problem with the original pertronix was amps heat build up from the coil neg supply "fried" the IC chip buried in the heat insulating epoxy module body if the ign was left on,,,only way for the module to stay cool is the teeny tiny metal base surface area "heat sink"....
fried chip=no blinking test lamp

how they solved that lack of heat sink on the pertronix II I'm not sure,,,could just be a more "robust" IC chip,,it doesn't require the 3ohms/4 amps heat limiting that the original does need

[Trailboss71]

Thanks again red.That is a lot of good info.I put an old dual point mallory with a resister so problem solved.I will use the pertronix set up on another project.I think that i had a grounding issue. Points vs electronic it doesn't really matter to me as long as it works ,right. Thanks again

[Trailboss71]

Oh yea,they burnt out the first igniter jumping the the coil off the battery.I'm pretty sure that's what did in the coil too.I'm also not to sure there was anything wrong with the ignition switch either,lol