65silververt

http://www.breakerless.com/index.htm

or
http://www.lectriclimited.com/mainpage.htm

71scgc

I tried a Pertronix unit in my '71. Could never get it to run right. I ended up with a Davis DUI HEI distributor. It's fabulous.
I wouldn't use it in a C2 though. It would look WAY out of place.

Carter

Frankie the Fink

I wouldn't want to explain that to the cops!

69427

I appreciate the clarification.

65 396

Frankie,
I have a pretty new Pertronix III unit installed. It has less than 1000 miles on it. Now, The car occasionally stumbles upon acceleration, mostly in 4th gear. It only does this occasionally and it's more than a cylinder miss.It is not a fuel issue. I'm afraid I'll be left on the side of the road so I'm not driving it currently. Does this sound anything like the issues you experienced with your Pertronics units?

Nowhere Man

Back in the beginning of this thread I asked for real hard data to back up all the claim of benifits of any of the point conversion kits. But no one has provided any yet I'm trying to keep a open mind on this subjuct but all I get out of it is I spent more money on this so it has to be better then the old technology

ricks327

As I stated earlier (yesterday), 10+ years with absolutely no problems with the Breakerless ignition system from Letric Limited.
Rick

Nowhere Man

Same can be said with points, TI, and HEI. All that means it works.

ricks327

You asked for any benefits. My response is that no removal of ignition shielding, no buying quality points and no worries for 10+ years. Driven many miles, including 3000+ miles on the Hot Rod Power Tour in 10 days. There are many benefits. Pick your poison, I prefer less maintenance, especially removing and replacing the ignition shielding!

69427

Well, if the designers of the conversion kits don't do anything stupid, there are two electrical improvements that should automatically present themselves. The substitution of a transistor (instead of slow acting points and condenser) shuts the coil off a ton quicker. This quicker turn off of the coil primary current will cause the coil to ring up to a higher maximum voltage, compared to the maximum voltage that a slow acting points/condenser can create. This will allow a slightly greater gap (intentionally or via wear) to be accommodated before misfire occurs.
Also, the faster voltage ring up (due to the faster current shutoff) reduces the time that coil secondary energy is bled off/shunted across the carbon film on the plug tip insulator while the voltage is ramping up to a high enough level to arc over the plug gap. This improvement in efficiency allows a longer usable plug life.

That's the two "automatic" improvements. Better systems have additional benefits.

rnixon

Pertronix is an option, MSD is an upgrade. On my 67BB, I use a 6A box, MSD Corvette Billet, tach drive, vac. adv. dist. . and MSD coil. 25+ years no problems, no maintenance. Dist. uses stock GM cap and plug wires, coil fits the stock bracket, under the ign. shielding, 6A box is mounted out of sight inside the pass. fender. Advantages, instant starts, easily adjustable timing [ vac.& centrifugal ] never a missfire, spark plugs last Forever, and for those who care, better gas mileage. Disadvantages, It ain't cheap! $800+

69427

Still trying to find out why you think stock coils are so lacking in performance and reliability.

Frankie the Fink

One thing the points zealot say that is quite true is that the Pertronix is generally "all or nothing"; its either working beautifully or fails outright and completely. So, I think you have some external factors causing your problem. I would revisit the installation and make sure your unit is snugged down tightly and properly positioned and that the small wire that goes to the vacuum advance plate in the distributor is in good shape. (I found my '63 wire hanging on by two strands once). Next, if you have ignition shielding make sure that a) none of your wires are being cut by the sharp bottom edge of the top shielding and that, b) nothing can short to the upper inside of the shielding (e.g. ignition coil wires, etc..) when you mash it down to install it.

If you adjusted the Pertronix rev limiter, recheck that setting as it uses "spark stealing" and what you are experiencing may be the limiter 'kicking in' at some unacceptably low RPM.

Beyond this you could have a completely unrelated problem, fuel filter, accelerator pump going south or an ignition coil acting up...

65tripleblack

First let me commend you on post #70:

"Well, if the designers of the conversion kits don't do anything stupid, there are two electrical improvements that should automatically present themselves. The substitution of a transistor (instead of slow acting points and condenser) shuts the coil off a ton quicker. This quicker turn off of the coil primary current will cause the coil to ring up to a higher maximum voltage, compared to the maximum voltage that a slow acting points/condenser can create. This will allow a slightly greater gap (intentionally or via wear) to be accommodated before misfire occurs.
Also, the faster voltage ring up (due to the faster current shutoff) reduces the time that coil secondary energy is bled off/shunted across the carbon film on the plug tip insulator while the voltage is ramping up to a high enough level to arc over the plug gap. This improvement in efficiency allows a longer usable plug life.

That's the two "automatic" improvements. Better systems have additional benefits. "



I learned something. Thank you. It appears that you are better equipped to compare pre-emissions coils to later and/or race/performance units. I retract anything that indicated that older coils were unreliable, but "flaccid, weak, and marginal" remain. They are "fine" if your engine is in an optimal state of tune, including brand new plugs. "Better systems have additional benefits" begs for an explanation.

Breakerless SE has a great write up about coil voltages on their website. I believe that MSD has a similar explanation. Somewhere in those explanations it states that (around?) 12 kv are required to jump a .035" gap under cylinder ambient conditions seen by vintage engines of average power production. Richer (or leaner) mixtures require more energy to jump that same gap (as well as being harder to ignite). Higher cylinder pressures developed by more efficient and powerful engines require the same. Stovk, pre-emissions coils develop (about?) 20 kv (less than 19 kv at high RPM when triggered by points). This means that there is (about) 7-8 kv in reserve before misfire occurs. This reserve can easily be taken up by mechanical irregularity in the points, leaky wires, rotor to cap gap, spark plug gap, etc. If this happens, then misfire becomes more frequent and although the driver doesn't feel it, the spark, not being optimal, causes incomplete combustion and inefficiency.

More powerful coils, capable of producing 45-50 kv allow wider spark plug gaps, which are more efficient at lighting the charge in the combustion chamber. They also allow a greater reserve due to inefficiencies in the secondary ignition circuit. When using higher energy coils, it is important to use 8.5-9 mm wires rather than 7mm otherwise leakage becomes a problem.

I'd be interested in hearing your explanation of this, as you appear to be equipped to explain it in a more technical manner.

tbarb

Can you tell me if you had a difficult time timing the engine with a timing light using this Petronics III. I installed one on a 1967 L-79 and the timing light kept jumping all around, ended up timing by ear best I could.

No issues with Breakerless unit but I am curious if the Petronics timing problem was just on this car.

I would check your accelerator pump adjustment and ALSO your accelerator pump check valve adjustment. It's the BB held captive just above the pump diaphragm and it's clearance is supposed to be approx .010-.015.

The first part of the pump shot will be wasted seating the BB to the seat and in high gear the load on the engine along with low RPM and the created lean condition by opening the throttle blades needs all that instant shot of fuel.

65 vette dude

I recently changed my points that have been in my car since 2008......not that they needed changing, but I felt kind of guilty. The two good things about points are, they will NEVER leave you stranded on the side of the road, and the cost. Pertronix when they fail.....and eventually they will, just like all electronic devices eventually do.....cometh the tow truck....unless your smart enough to be carrying points in your glove box......but then again, I still have a carb, Delco shocks, non-resistor spark plugs, and bias ply 775x14 tires on my 65. I try to keep my car as close as possible to the way the General made it......I thought that was the whole point of owning a classic car.

ELEFUNTMAN

In regards to the coil. I don't recall the exact numbers and I hope I can explain this in an understandable way.


A stock GM points type coil has say 50,000 volts, as the RPM increases the voltage drops, at a slow rate, so at 7000 RPM it still has 35,000 volts.


A Mallory or Accel coil has say 100,000 volts, for a very short RPM time, as the RPM climbs, the voltage drops, and say at 7000 RPM the voltage is down to 20,000 volts.


A new MSD or Pertronix coil has 80,000 volts, and maintains the voltage for a long RPM span, however still dropping as RPM climbs, so lets say 70,000 at 7000 RPM.


All the numbers are for example as I don't know the actual numbers, years ago when I actively raced NHRA stock eliminator I attended a few classes, so reaching way back into my brain housing group this is what I recall! My experience a the electronic will start easier, and no maintenance. A spark is a spark, however points float around 7000 RPM, and need maintained.

Frankie the Fink

There are several instance of points leaving members "srtanded alongside the road".
Either the points or the condensor. I've posted them before but not going through that again.

I've never had a problem timing an engine with a Pertronix in it and I've prob done a couple of dozen conversions over the years on my (and others') cars...

DSR

If you read the instructions for the Pertronix 2. I believe it says you have to run a coil with the correct resistance of 0.6 ohms. I use the Pertronix Flame Thrower 2. It has worked fine for 30,000 miles.
Dave

69427

First, thank you for the kind remarks.

I wrote a sticky in C3 Tech explaining the physics of our ignition systems. I tried to walk the fine line of explaining stuff to be understandable to the average enthusiast, without getting into too much dry boring engineering geek speak, but also trying to avoid inadvertently insulting anyone's intelligence. (It's everyone's individual decision on whether I was successful in that endeavor. ) Please take a peek at the sticky, and if you have any questions about what I covered, or neglected to cover, please feel free to start a thread here in C2. If the question has some broad appeal I'll steal it and add it to the sticky.

Again, thanks.