Pertronix experts?

[47convert]

My friend's '34 Cabriolet has a stock 305 Chevy with a Pertronix distributer. He tells me it was running but all of a sudden it won't start. There is 12.5 volts going to the Ballast resister and 12 from there to the coil. The timing seems to be OK but there is no spark at the plugs. If I pull the coil wire from the distributer and hold it very close to ground, I can see a very very small arc to ground but certainly not enough to fire a plug. You can barely see it in the dark. The coil is a new Pertonix unit and the distributer is a stock Chevy that someone has converted to Pertonix. My plan is to change the coil and then substitute the distributer for a stock point one if the coil doesn't work. I've never used a Pertronix, but I hear they're good and quite reliable. Any ideas would be appreciated. Do you need a resister with these distributers?

[Okiedokie]

Have you checked to see if maybe the screw holding the module in posistion may be loose creating excessive gap? I have ran the one in my 46 without a resistor for a long time with no problems. Joe

[wayne petty]

i would make a new ground lead from the movable breaker plate that the base of the ignitor mounts on... to one of the hold down breaker plate hold down screws that go into the distributer housing...


why...

12 volts from the key supply the + side of coil... and the red wire on the module..

the black wire from the ignitor module pulls the (-) side of the coil primary to ground to complete the circuit...

the ignition module is grounded through its base... but since its sitting on the moveable upper breaker plate... and that is sitting on plastic wear pads...

even GM put a little braided ground strap...

why is this even important.... for the coil to get full power... the ground side of the control circuit has to be perfect...

there have been racers that have installed cylinder heads with so much sealer.. that all 4 spark plugs in one head would not fire...

ground wires from the back of both heads to the distributer housing cured the spark return circuit..


here is a picture of it...

http://images.wrenchead.com/smartpages/partinfo_resize/STA/DDL21_FULL.JPG

from standard igniton... #DDL21  

make one your self.. with a pair of #10 ring terminals..  but use wire that flexes... and put a bend in it...  as the breaker plate has to move...


http://contentinfo.autozone.com/znetcs/additional-prod-images/en/US/c11/30-1835/2/image/8/

here is a view of the top of the distributer...  you can see the ground strap under the vacuum advance hold down screw... and looped to the end of the points hold down screw...  i normally have to use a piece of vacuum hose and apply some vacuum to the advance to get the breaker plate to move enough to remove the screw...

[47convert]

Good info. Thanks. I haven't even looked inside the cap so I'll do that next. How much of a gap is reccomended?

[kb426]

One of my friends is an industrial engine supplier. They used to sell lots of Pertronix units. They had a fairly high failure rate.

[57larry]

I'm using 3 of their units, no problems, guess I'm lucky?

[kb426]

These were in irrigation engines that run for months at a time. If anything would give it the test, that would.

[Okiedokie]

I can't tell you how many Pertronix conversions I have done on mine and my kids cars over the years. I have never experienced a failure. Joe

[wayne petty]

i don't think he has a total failure.. but a bad ground inside...

movable upper breaker plate to housing..

housing to intake...  (painted or coated housing or hold down clamp)

intake to head...

bad ground wire to the battery cable.. but then it may crank slow..

[enjenjo]

We had hundreds of these in lift trucks at work. The failure rate was near 50 percent, but they failed in the first few hours of use. After a day or so, if they had not failed, they never had to be touched again. Pertronix replaced all failed units no charge. So we continued to use them.

I have not had that good service on cars. Every one I have installed has failed within the first 100 miles. The last one failed in such a manner that it blew the coil up, spraying oil all over the engine, causing a fire. So I no longer use them. Even with the free replacement.

I have had zero problems with Mallory conversions in Delco bodies. So that is what I use.

[wayne petty]

ever hear shot gun going off noises coming from under the hood of a gm car.?   equipped with a coil in the cap HEI?

i bet that when closely examined...  that the little ground strap that fits into the cap before the coil goes in..  got left out..

that ground strap...  connects to the center wire of the 3 wire harness and grounds to the housing through the strain relief hold down screw...

since the frame of the coil has the windings attached... via the black wire out of the coil...

the coil frame can build up tremendous amounts of voltage...    with quite a few amps of power...  enough to usually blow the wires off the coil when it finally goes... usually taking out the module also..

~~~~~~~~~~~~~~


for the morning humor... years ago..  i ordered a motor for my brother in law.. had it drop shipped to his place up in bellingham..  he and his helper installed it..  85 suburban ..   on one of the first drives.. they had gotten about 80 miles down by sea tac airport..  had blown up 3 coils and modules by the time they called me..   i ask them if they had swapped the  ground strap over..  they both said what ground drap.... i gave them the napa part numbers told them to find a local napa as there are a bunch of them there..  after i hung up.. i called the 3 local napas to sea tac.. described my in law and his helper...  had them put the parts on the counter..   i did not hear from him for about 6 months..

when i did.. before he hung up.. i ask about the fix. he told me of how strange it was.. they walked into the napa store.. were greeted by name as they walked through the door.. the exact parts they needed were on the counter..   they could not understand how that could be.. freaked them out..  then i spoiled it and told him that i had called ahead to 3 different napa stores..   described david.. 5'6 and korean... and rob.. 6'4 white and 3 teeth..     i still see him once in a while... even though my sister is gone..   he managed to open a restaurant about 5 blocks from my house..  right across from a big construction project.. i guess he did not think it was a new high school.. and the kids paint and scratch his walls up almost daily on their way home.. more weird happenings.. my best friend ended up working for him at the farmers marked for six months before i noticed who he worked for.. small world..

[38HAULR]

As prev suggested ,check the ground wire in the distributor.
Simple theory of operational matters ,is that "If it was working and stopped,then something has become disconnected or failed".
Simple tests.  Make sure you have volts at the coil +ve during cranking.
And check for volts at coil +ve with ign "on"
Before resorting to swapping distributors,if you have a set of points, swap them in and see if it starts.
If it starts,
The Pertronix module has simply failed.
Before this step, you can also disconnect the distributor from the -ve coil lead, pull the coil HT wire from the distributor cap  end  and  hold it close to the engine block [plug gap width or a fraction more]. with ign "on" .
By flashing the coil -ve terminal to the block ,you should see a High Voltage  spark at the HT wire.  This at least tests functionalty of the coil.
Frank.

[Mac]

I remember reading that Pertronix modules want full 12V and shouldn't be fed thru a resistor. You may want to contact Pert. and ask if the unit model you have needs a ballast or not.

[38HAULR]

I have one of these in my Mustang,with the conventional 8v ballast coil system ,running with no probs at all.
Frank.

[40 Chev Coupe]

Does anybody have any info for or against the distributers that Petronix sells?