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Electronic Ignition Choices

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NW_SpriteGuy

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It is my understanding that with standard factory ignition, even if you have it dialed in to perfection, you can only reach about 92% firing/timing efficiency. If you change to the pertronix ignition system, you might be able to achieve 95-96% efficiency. However, if you install a Crane system, you can virtually obtain 98-99% efficiency. The reasons for the difference is that the Pertronix system apparently uses a "magnetic field sensing" mechanism. When the Pertronix rotor comes into the "general area" of the magnetic field, it senses that's the time to fire. While this system is a great improvement over the original factory system, there still remains a less than/greather than plus or minus area. In the Crane system, I've been told it's an optical light beam system. When the light beam is broken by the rotor, it's time to fire... it's immediate and narrows the plus/minus magnetic field (of Pertronix), down to a precise instaneous moment and thereby providing the 98-99% efficiency. Does anyone on this board have any experience between the two? Can anyone verify and/or confirm what I've been told? Pros/cons of each? I'm seriously interested in upgrading my original system in the next few weeks getting ready to enjoy the LBC for the summer.

NW_Spriteguy
 
"It is my understanding that with standard factory ignition, even if you have it dialed in to perfection, you can only reach about 92% firing/timing efficiency."
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I assume that you mean always firing at the exact same distributor position. Maybe positional accuracy or repeatibility.
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"The reasons for the difference is that the Pertronix system apparently uses a "magnetic field sensing" mechanism. When the Pertronix rotor comes into the "general area" of the magnetic field, it senses that's the time to fire."
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The Pertronix uses a Hall effect sensor which is extremely accurate. The "Magnetic field sensing" or the coil & reluctor, is an older technology which has a few problems. Hall Effect sensors such as used in the Pertronix, are used on late modern engines due to their extreme positional accuracy. Some even measure the tooth positions on the starter ring gear.
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"While this system is a great improvement over the original factory system, there still remains a less than/greather than plus or minus area. In the Crane system, I've been told it's an optical light beam system. When the light beam is broken by the rotor, it's time to fire..."
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The positional accuracy of the optical or infrared light beam system is dependent on the width of the shutter slots. Because of the possibility of dirt contamination in the shutter slots, they cannot be made extremely narrow. The same contamination problem applies to the sending light & it's receiver.
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"I'm seriously interested in upgrading my original system in the next few weeks getting ready to enjoy the LBC for the summer."
"NW_Spriteguy"
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The technological progression of ignition triggering has adavanced in about this order;
Points
Optical
Magnetic
Hatt Effect

A few such as Lucas, use the "eddy current killed oscillator" before going to the magnetic.

In reality, extreme timing accuracy is only needed on the modern, tightly controlled, low emission engines. The difference between 92% & 97% timing accuracy will be overshadowed by the fuel mixture, temperature, fuel quality, & valve timing variations of the old technology engines. Fuel mixture alone can probably cause 5% variation in the time it takes to propagate spark ignition.

Any ignition triggering system that suits your taste will be more than adequate on an older engine.
D
 
Dave,
Thanks for the information. So if I understand you right, you're saying the Pertronix "Hall" effect type ignition is the newer technology and it's the best? Which one is easier to install? What about later... when problems pop up? Which system is easier to diagnose problems with? I was told that the electronic box that goes with the Crane system has a LED light on it. If it's on... the thing is working fine and you can rule out ignition problems. Off however, and you've found your problem. Can it really be that simple? Good point about the light slots getting dirty with the Crane system. One thing I have noticed is that I sure see a lot of the Pertronix systems installed... not very many Crane systems. That's why I was thinking the Crane system might be the newer technology and really hasn't caught on yet with most people.

-Don
 
Hi Don,

"Dave,
Thanks for the information. So if I understand you right, you're saying the Pertronix "Hall" effect type ignition is the newer technology and it's the best?"
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It's the best technology, not sure if it's the best implementation of this technology, but a very good one.
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"Which one is easier to install? What about later... when problems pop up? Which system is easier to diagnose problems with? I was told that the electronic box that goes with the Crane system has a LED light on it. If it's on... the thing is working fine and you can rule out ignition problems. Off however, and you've found your problem. Can it really be that simple?"
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I don't really know. The Pertronix is very easy to install, but does require the correct coil type, ballasted or non-ballasted, as the car application dictates. It is also prone to immediate failure if the wiring is connected wrong on the first try. Early Pertronix units had some reliability problems but that has long been cured. The Pertronix is completely self contained & has no external box. Not sure how helpful or reliable an OK led is. Both systems stop when something goes wrong. What do you do when the light goes out? You can get a Pertronix for around 80 to 90 dollars. Don't know what the Crane costs.
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"Good point about the light slots getting dirty with the Crane system. One thing I have noticed is that I sure see a lot of the Pertronix systems installed... not very many Crane systems. That's why I was thinking the Crane system might be the newer technology and really hasn't caught on yet with most people."
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I personally have a Pertronix plus a spare which I have never needed. It would take about five minutes to replace the unit at roadside. Two screws & two wire plugs. Nothing to adjust.
D
 
Dave,
The Pertronix system not having any additional boxes to mount in the engine compartment is a plus! $80-$90 is a plus also. Don't like the sounds of mixing up wires once and ruining it however - will need to make darn sure it's done right the first time! No second chances. What determines if your coil needs to be ballasted type or not? And, would you recommend that the coil be changed out and upgraded at the same time of installing new ignition system? I appreciate your comments.

-Don
 
Don,

The coil current should be no more than about 5 amps on a 4 cylinder car & 7 to 8 amps on 6 & 8 cylinder cars. This means that the coil and/or ballast combination for 4's should be no less than 2.7 ohms, & 6&8's around 1.7 to 1.5 ohms respectively. This is because the coil "on" time (dwell) is longer with less cylinders which causes more total heating of the coil & ignitor unit. Some car models have a built in ballast, some don't. If you measure the voltage from coil to ground & it has a ballast it will show about 6 to 8 volts instead of 12.

Of course the ultimate in long dwell time is leaving the ignition switch on without the engine running. Under this condition the coil & ignition unit can get quite hot. I experimentally left the switch on with engine off on my four cylinder engine with 2.7 ohm coil. After two hours the coil & Pertronix were quite hot, but no damage. (Pert. does not recommend doing this) Some more expensive electronic ignitions have a safety circuit that shuts the current off.

If the present coil meets the current limit requirements & is working, no reason to change it, unless you just "want" to. You can buy, borrow or rent an ammeter & measure it. Or as above, measure the present coil voltage. If it is 6 to 8 volts, use a 1.5 ohm coil. If it is 12 volts use a 3 ohm coil.

The same current limits are generally true for points ignitions also. The more current the quicker the points burn.
D
 
The Pertronix Ignitor II has the automatic shut off feature as well as variable dwell time. The variable dwell optimizes the dwell according to the engine speed.
 
just a point i wasnt aware of, about measuring coil resistance. measure from center post to either side post of coil. took me a few to figure that one out.

mark
 
[ QUOTE ]
just a point i wasnt aware of, about measuring coil resistance. measure from center post to either side post of coil.
mark

[/ QUOTE ]
Mark,
Not sure how you came to this conclusion. A typical coil for non-ballasted use (the Lucas HA12) is constructed with a primary winding of a few turns of relatively heavy wire (with approximately 3 ohms resistance) & a secondary (high voltage) winding of many turns of lighter gage wire (with about 7,000 ohms resistance). Both wound around a laminated iron core. One end of the secondary winding is connected to the HV center terminal, the other end to one of the outside terminals. The primary winding is connected between the outside terminals which results in one outside terminal being common to one end of both primary & secondary windings.

With this construction, you would measure 3 ohms between the two smaller outside terminals. The center terminal would read 7,000 ohms to one outside terminal & 7,003 ohms to the other outside terminal.

The 3 ohm primary winding resistance, the two outside terminals, is what determines how much current flows in the coil & its trigger or ignitor circuit.

Some cheap digital VOM meters don't seem to give very accurate readings of coil resistance. A really accurate ohm meter will show the above results.

There are some variations of coil internal wiring that can give different results, but the resistance between the two smaller primary terminals is the important one in determining the circuit current. These terminals will be marked 'CB' & "SW" or + & -, depending on the particular coil.
D
 
hmmm, guess my meter is not that good. i read no resistance across (+) to (-). but when i measured to the center from either side i saw resistance. similar to what i have been reading about here. i guess i must retract my statement

thanx for setting me straight

mark
 
One other observations here.

Often, especially with economy meters, the lead resistance is significant. If I were measuring the coil resistance, I would first short the leads of my meter together several times and note the lead resistance (typically .1 to 1.2 ohms!) and subtract that from the coil reading. If the lead reading is higher than 1 ohm, I would clean the lead contacts by removing and re-inseritng the leads into the meter 5-6 times. If the reading didn't improve, I would look for a better meter to make this measurement.
 
Question has anyone installed the Pertronix Ignitor in the 45D4 CEI setup? I was wondering if the CEI unit then gets scrapped or what? I would definitely consider doing this as my 45D4 M distributor seems to be in good shape and it would be cheaper to swap out the mechanical parts.
 
I have had 2 Petronix units quit on me.
1 lasted 11 months, the other a few weeks.
Others never have a problem with them.
I guess I am just lucky /ubbthreads/images/graemlins/wink.gif
I now am running a cheap generic electronic unit made in the UK that a friend sent me. So far so good. But I do keep a spare dizzy with points ready to drop in.
 
I've had a pertronix in my wife's '68 mustang for over 10 years with no problems. Maybe pertronix left somethin out of the set up procedure for lbc's that causes the system to fail prematurely?
 
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