Points to Electronic Ignition Conversion

[korvettekarl]

I have to go with the pertronics on this one. The only time one has failed on me was my fault. I have converted 6 cars now and all doing just fine. I like the fact that I get a hotter spark with the pertronics. It just burns cleaner. Starts easier. To each his own, but I'll go with pertronics.

 

[Florida Guy]

Ernie,
I stuck a Pertronix in my 64 Ford with a 390 CID and it was a big improvement over the stock points. The stock coil works fine. As a backup, I tossed the points in the glove box 4 years ago and it is still there. I recommend the swap.

 

[Vettehead Mikey]

Didn't the '74 big block come with HEI? I thought they were the "test bed" for the GM-wide change in '75.

'75 was the first year they came on Corvettes. Please note that the poster DID NOT ask about HEI, he asked about a pertronixs (POS) and similar conversion kits. BIG difference.

Pertronixs (POS) is NOT HEI.

 

[Vettehead Mikey]

I like the fact that I get a hotter spark with the pertronics. It just burns cleaner.

There's two of the most common urban legends of these widgets. They DO NOT provide a hotter spark, or make your engine burn cleaner. They simply substitute an electronic 'switch' for the mechanical switch (the points and condenser). The 'strength' of the ensuing spark is a function of the coil, which remains unchanged.

Uh ho, I hear pqtr winding up again!

 

[pgtr]

'75 was the first year they came on Corvettes. Please note that the poster DID NOT ask about HEI, he asked about a pertronixs (POS) and similar conversion kits. BIG difference.

This is at least the third time Mikey has made the claim there is a "big difference" between these systems. Considering both Pertronix and GM use magnetic induction triggering (whereas some other aftermark units use other systems including optical and infrared) - I'm still curious to see if Mikey can explain to us what the "big difference" is... :confused Come on Mikey, we've been enduring your seemingly irrational chip-on-a-shoulder rant :bash intruding upon legitimate discussions about ignitions systems for quite some time now - Rather than running around telling us about these 'abysmal failure rates' based on a sample size of, uh, um, one, tell us about this "big difference." Please. :eyerole

 

[pgtr]

Uh oh - I think I heard a blatantly false statement being presented as fact again. :eyerole

There's two of the most common urban legends of these widgets. They DO NOT provide a hotter spark, or make your engine burn cleaner.

This is a completely erroneous statement. :ugh It a fact is that an electronic ignition system with no other changes produces both a HOTTER and FATTER spark energy. That's basic physics and electronics and while we can all be impressed by the flat earth society's tenacity - the fundamental verifiable physical properties of an IC ignition system of either sort does not change.

They simply substitute an electronic 'switch' for the mechanical switch (the points and condenser). The 'strength' of the ensuing spark is a function of the coil, which remains unchanged.

This statement underscores a fundamental lack of understanding as to how a coil induces a current thru the collapse (switch) of a field and the significant role an electronic vs mechanical switch plays in this process. First the mechanical switch is replacd by a magnetic induction ring (HEI, Pertronix, Accell) or other similar mechanism as used by Mallory, MSD etc. Once the signal is generated by the ring, the actual switching occurs in the electronic module (HEI, Pertronix, MSD, whatever...). Actually points can even be used to trigger an electronic ignition - they use far less current and last indefinately and should not be confused with a points based system. The ability of solid state electronic switches to more precisely open and close the coil circuit much quicker than a mechanical switch ever could and thus it's ability to dramatically better control saturation times of a coil is what produces a fatter, hotter spark.

To summarize - yes a switch is replaced but no it's not so "simple" - rather the physical characteristics of such a switch make all the difference in the world as to how hot and fat the spark is which in turn should be important to early C3 owners given the leaner combustion characteristics used in engines from 68 on.

Now let's follow Mikey's logic for kicks shall we? Background junk: Back in the day GM had dual point ignition right? Why? Because collapsing the points twice induced slightly more spark energy potential out of the same coil and they needed a hotter spark for hi perf engines. Of course it was twice as much maint hassle and eventually this system was retired back in the early 60s sometime. Fast forward to the C3 era - with overly lean engine setups - ignition performance again become key to provide consistent dependable ignition in less than optimal scenarios. They needed both a hotter and fatter spark (maybe dual point and certainly HEI fit this bill) AND they needed longevity (electronic ignition rules this one).

So now we arrive at the question that Mikey should answer. Mikey asserts that electronic ignition does not produce any hotter or fatter spark than a single point (yes I know but bare with me ). We know GM produced a dual point for a hotter spark. Therefore an ancient dual point GM distributor will produce (according to Mikey's logic, not mine) a hotter spark than an electronic ignition such as Pertronix right? :crazy So Mikey - riddle us this: why don't all the big shot engine builders and exotic hot rodders and racers (except for classes that mandate it) run dual point ignition since by your logic that would have hotter/fatter spark?

 

[JohnZ]

There were two reasons HEI was developed (I was there, you weren't):

1. As emission controls began to be capable of maintaining leaner average A/F ratios, more secondary spark energy was necessary to ensure consistent combustion (freedom from misfires, especially at idle) of those lean mixtures; that was handled by the new integral HEI coil that operated at a full 12 volts instead of the previous coils that operated at 7-8 volts except when cranking.

2. The EPA required a 5-year/50,000-mile warranty on all emission-related components (which is now 10/100 on today's cars), and no customer maintenance intervention was allowed during that time in order to keep them operating below the required emission limits. This is why the electronic triggering was developed, as it required no periodic maintenance (like changing points and setting dwell) and no adjustments.

It was as simple as that. Really. The method of triggering makes no difference whatsoever in the secondary spark energy; all that matters is dwell time to saturate the coil windings, and a switch to open the circuit so the field can collapse, and an electronic switch requires no maintenance.

 

[pgtr]

Didn't the '74 big block come with HEI? I thought they were the "test bed" for the GM-wide change in '75.

I'm thinking what you might be remembering here is the Pontiac 'Unitized Ignition' system from about 71-73 optional on 455s but I don't know much at all about those. That was the forerunner to HEI.

Ford had it's 'Solid State' system optionally avail in '74 and standard in '75. AMC had it's 'BID' system in production by '75. Actually Chrysler was the first to standardize electronic ignition - I think they had an electronic ignition (external control module) system out on *all* their models by about '73 or so, 2 years ahead of the rest of the pack.

Despite shrill denials to the contrary - to address various issues relatd to emissions, widening plug gaps, dependality etc - R&D was well under way in the late 60s by the OEMs for electronic ignition solutions. They made initial appearances in the early 70s and were standardized between 73 and 75 on everything.

 

[craig32]

R&D was well under way in the late 60s by the OEMs for electronic ignition solutions. They made initial appearances in the early 70s and were standardized between 73 and 75 on everything.

This is what I was trying to point out - GM did all the research and development years ahead of release, aftermarket companies do not. As I've read others post, as they keep improving unit after unit (such as engine, then transmission, then differential, then suspension - and the universals can't handle it because they are the weak link) That's why I like the 'factory' set-up. Just my opinion.

Craig

 

[pgtr]

GM did all the research and development years ahead of release, aftermarket companies do not. As I've read others post, as they keep improving unit after unit (such as engine, then transmission, then differential, then suspension - and the universals can't handle it because they are the weak link) That's why I like the 'factory' set-up. Just my opinion.

The point I was trying to make was that there was, contrary to Mikey's position, indeed a need to develop electronic ignition in the late 60s and early 70s. Why? Because 'standard' points based systems were not capable of sustaining the emissions, mileage and longevity needed by the marketplace and worsened by less than ideal engine calibrations of that era. Rather than an Accell, Mallory, Crane, Pertronix or MSD, which are designed to fit under the stock cap - one can always retrofit the GM HEI unit in an older car as they are available with tach drive. Warning: they come from the 'terrible' aftermarket community however! Be forewarned that HEI units may not have the best curve profiles in their design - in stock trim they are inferior to aftermarket units in this regard (and older points systems) but they CAN be re-worked to rival aftermarket curve characteristics or earlier curve characteristics on standard distributors from the 60s.

Actually no they (OEMs) do not "they keep improving unit after unit". To the contrary - there were essentially NO improvements in standard ignition in the decades leading up to the advent of electronic ignition in the mid 1970s. Indeed GM DROPPED the dual point distributor and the optional transister ignition from their lineup didn't they? Hardly an improvement. Just look at the 1971 L48 distributor - probably the single worst advance curve ever installed on a C3. Ignition systems were essentially stagnant as to development in widespread production until about '73 or '75. Then they made a quantum leap forward. And once again ignition systems were stagnant as to improvement...

Aftermarket development of kits designed to be retrofitted using otherwise stock components goes back at least 30+ years. For those of us who own older (pre '75s) - they offer kits customized and tailored to be retrofitted. GM does not - though one can certainly retrofit an entire HEI system including distributor of course. Pick your poison - both Accell, MSD, Mallory, Pertronix and Crane as well as retrofitting a GM HEI offer the fundamental advantages of electronic ignition.

 

[pgtr]

;worship;worship;worship;worship

(I was there, you weren't):

:BOW:BOW:BOW:BOW

1. As emission controls began to be capable of maintaining leaner average A/F ratios, more secondary spark energy was necessary to ensure consistent combustion (freedom from misfires, especially at idle) of those lean mixtures; that was handled by the new integral HEI coil that operated at a full 12 volts instead of the previous coils that operated at 7-8 volts except when cranking.

In the days of yore for high perf engines of the 60s - special ignition needs were identified - e.g. the dual point ignitions and transistor ignitions to be specific to Corvettes . Later as this gave way to the era of leaner engines (early C3s?), widening plug gaps and such, the need didn't lessen - only the reason changed. Essentially the same thing was needed - only this time it was eventually addressed using a different type of improvement in ignition over the old solution fo dual points and such - electronic ignition in 1975. Late to the party :z but welcome nonetheless.

The misfire point is a good one - in the early C3 era some of the problems from the lean engines such as acceleration glazing and subtle misfires particularly at idle (not readily detectable) were remedied by the eventual intro of electronic ignition. It's the consistent ability to fire leaner mixtures that gives electronic ignition an edge in gas mileage over points in the same application.

It was as simple as that. Really. The method of triggering makes no difference whatsoever in the secondary spark energy; all that matters is dwell time to saturate the coil windings, and a switch to open the circuit so the field can collapse, and an electronic switch requires no maintenance.

Crack open your books son. :CRASH The near discrete switching capability of an electronic control is PRECISELY what has an affect on dwell time, saturation and ultimately 2ndary spark energy over the slower and less precise mechanical switching mechanism. :gap

 

[BarryK]

pqtr

you do not want to question JohnZ when it comes to the validity of his information :nono
if you do you will come out on the losing end.
If you are unaware of who John is, try using the search function........ when he says he was there, he doesn't just mean he was alive and enjoying these cars at that time, he was there in the Chevy engineering dept, working with Zora himself, helping to design and build these cars.......
If there is anyone on this forum that can be considered a true expert on these cars and any function of these cars than simply that person would be John.

Crack open your books son

John doesn't need to crack open the book, he most likely wrote the damn thing and knows it better than anyone else.

 

[pgtr]

you do not want to question JohnZ when it comes to the validity of his information

I guarantee he puts his pants on one leg at a time and yes (shock and awe :eek ) he makes mistakes as do all of us (this being the second one I've personally encountered).

John doesn't need to crack open the book, he most likely wrote the damn thing and knows it better than anyone else.

If you want to unquestionably accept everything someone says as gospel :Silly - that's fine but it doesn't change the basic truth as to the the significance of the near discrete electronic switching role in generating greater spark energy. But of course he could always put forth his own theory :blue: as to where electronic ignition get's it's greater spark energy (all other things being equal) over points.

 

[JohnZ]

But of course he could always put forth his own theory as to where electronic ignition get's it's greater spark energy (all other things being equal) over points.

I don't need my own theory - it's well-known already. Switching methods have no effect on secondary spark energy - that's a function of coil efficiency (primarily rise-time improvements), as dwell remains constant. Most aftermarket "electronic ignition" systems (not just electronic switch conversions) employ other techniques like capacitive discharge and multiple discharges at lower rpm for increased secondary spark energy, and the newest OEM systems utilize individual coils for each plug, so each coil only needs to saturate and discharge once every other revolution instead of eight times every other revolution.

In spite of the lack of statistics you seem to be so enamored of, this stuff really isn't rocket science; referring back to the beginning of this thread, electronic switch conversions and electronic ignition systems are two completely different animals. Points systems with 7-volt coils weren't good enough for lean mixtures and were illegal under EPA regulations, and that's why the HEI system replaced them. HEI was a stop-gap solution that filled the need and met the legal requirements on the road to progress at the time, and today's totally computer-managed engine control systems will continue to evolve. Don't make it out to be any more complicated than it really is, and recognize that marketing hype has become almost as sophisticated as engineering; the average person knows ZOT about engineering, but a slick marketing campaign can (and does) convince many of them to buy almost anything, whether they need it or not. Marketing seldom involves facts.

 

[BarryK]

If you want to unquestionably accept everything someone says as gospel :Silly - that's fine ...........

I don't unquestionably accept everything one person says but when a subject such as this which has been brought up countless times previously, and basically has already been beaten to death, and John and many others whose knowledge I accept as many times more than mine will ever be all state the same thing on here and on various other Vette forums than I do accept it.
I know John's qualifications, and SWCDukes, and others, that all say the same thing. I sure don't know yours.
Based on what I do know and based on what I know of the backgrounds of these other people than yes I'll accept their stand on this issue.

I'm done with this

 

[pgtr]

I don't need my own theory - it's well-known already. Switching methods have no effect on secondary spark energy ...

My gosh he's going to sit there and pontificate that a fast, near discrete electronic switch profile has no significance - can we do any more in the reference dept than quip "I was there" and "it's well-known"? :W

this stuff really isn't rocket science; referring back to the beginning of this thread, electronic switch conversions and electronic ignition systems are two completely different animals.

These champions of breaker points ignitions sure seem fond of saying brand X aftermarket electronic ignition retrofit kits are not the same as OEM electronic ignition systems such as HEI et al. :z But what I find to be curious is they never seem to quite get around to explaing just what the difference is. Or are they implying a retrofitted HEI is better than an aftermarket brand X? Hmmmm.... :nono

Points systems with 7-volt coils weren't good enough for lean mixtures and were illegal under EPA regulations, and that's why the HEI system replaced them. HEI was a stop-gap solution that filled the need and met the legal requirements on the road to progress at the time, and today's totally computer-managed engine control systems will continue to evolve. Don't make it out to be any more complicated than it really is, and recognize that marketing hype has become almost as sophisticated as engineering; the average person knows ZOT about engineering, but a slick marketing campaign can (and does) convince many of them to buy almost anything, whether they need it or not. Marketing seldom involves facts.

Both of the points (no pun intended ) above are well made. But to add to the first point about HEI being a solution for lean mixtures - lean mixtures were already a fact of live PRIOR to HEI going into production in 1975! It was not a proactive solution - but a reaction/solution to reality.

The second point about marketing hype is equally well made in a general context of 'automotive aftermarkiatrics'. I'm personally not aware of any specific 'go fast' performance claims made by the various aftermarket ignition manufactuers - though they wouldn't surprise me. :gap What I AM aware of is the marginal solution a standard OEM ignition system had become by the early 70s for leaner engine configurations and that the OEMs ultimately solved this with their versions of electronic ignitions. Regardless of whether it's OEM or aftermarket - electronic ignition is the most intuitive solution to the issue for an earlier C3. The dramatic order of magnitude improvement in plug life, near elimination of tune-ups and potential for increased efficiency is icing on the cake.

 

[Koop]

Well, I read that stuff! It took as much time as I save not having to change my plugs once a year! There's 18 minutes I'll never get back!