Spark length of a points ignition compared to an HEI system

In summary, Multiple Spark Discharge (MSD) company showed their graph using Points, HEI, and Performance HEI comparisons, with little difference in Horse Power made, up to about 6000 RPM. The points and performance HEI traded the lead back and forth making more HP at different RPM's. Between 3000 - 6000 RPM the points and performance HEI traded the lead back and forth making more HP at different RPM's. My thinking is, as the mixture swirls around the chamber, the longer spark, though not as hot as the HEI, still manages to see and ignite the mixture, while the HEI sparks in a vacant area.
  • #1
Charlie Cheap
76
16
TL;DR Summary
How much is actually gained?
Having made/modified my own distributors for years, I was surprised to see MSD (Multiple Spark Discharge) company show their graph using Points, HEI, and Performance HEI comparisons, with little difference in Horse Power made, up to about 6000 RPM. I know a points mechanical system makes a longer spark but runs out of TIME to build spark at higher RPM. Multiple sparks can simulate the longer points spark but is not the same...but better than a very hot short ONE. Between 3000 - 6000 RPM the points and performance HEI traded the lead back and forth making more HP at different RPM's. The HEI might make more power at 5000 RPM but the points may make more at 5500. My thinking is, as the mixture swirls around the chamber, the longer spark, though not as hot as the HEI, still manages to see and ignite the mixture, while the HEI sparks in a vacant area. I am building a 2.3 Ford 4-cylinder out of an 85 Mustang, and to avoid any computer, I am using points. The 4-cylinder has lots of time to build primary voltage with only 4 lobes on the points cam. Just one reason for points. Using Borg Warner Division (BWD) parts, which use the best available materials for points/condenser/rotor/cap, and a Hot ACCEL coil with 1.2 ohms primary, 100 to 1 windings, a 1 ohm Ignition resistor, copper plug wires, and Platinum resistance sparkplugs, I think I will have plenty of spark to fire my 2-barrel carburetor fueled engine. Anyone have improvements or modifications I should make? I have nothing against computers and I am using one to type this, I just like simple if it works. For my purpose I see little if any gain to add a module (computer), O2 sensor, and probably more sensors if I go to Fuel Injection.
 
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  • #2
I'm not sure why you would need a computer for a non-points system. I've replaced the standard points ignition with HEI on many vehicles, without the need for anything complicated. You don't need computers and O2 sensors and the like for electronic ignition. Some kind of magnetic switch (hall effect maybe), or optical switch instead of points, and a capacitor discharge circuit to fire the coil is all you need.

Cheers
 
  • #3
I'd say it depends a little on what you are after. I would think multiple spark discharge could potentially lead to easier starts. I am generally in favor of simpler the better but I question the reliability of condensers for points style ignitions these days. I have had less than good luck. If you have a good source of reliable ignition parts, I'd go with points.
 
  • #4
I moved this thread to M.E./automotive. It may get other good answers there.
 
  • #5
mechanical points are good to about 0.025" spark plug gap. This one spark is limited to a few degrees crank shaft rotation. Newer cd ignitions on Detroit vehicles meant are good to jump a 0.060" plug gap. The MSD units do two things...makes a long spark at high RPM over more 20 degrees of crank shaft rotation and at low RPM these units spark multiple times to increase combustion chamber efficientcy.
dont be fooled with thinking wide spark plug gap means more horsepower. As a wise old champion spark plug adviser said once, you ca nthink wide is more HP until you start missing, then you will come back to 0.030" . i been there ever since. Been there thru the dual electrode thing, iridium trends, and lost a race caz the MSD was such a battery hog. Stick a photo optic cell in place of the points and go racing.
and learn how to index the electrodes.
 
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  • #6
cosmik debris said:
I'm not sure why you would need a computer for a non-points system. I've replaced the standard points ignition with HEI on many vehicles, without the need for anything complicated. You don't need computers and O2 sensors and the like for electronic ignition. Some kind of magnetic switch (hall effect maybe), or optical switch instead of points, and a capacitor discharge circuit to fire the coil is all you need.

Cheers
I misstated my question. I too have used HEI with the coil on top of the dizzy (distributor) without any computer or sensors. In order for the little 2.3 to make any real power it needs a turbo and fuel injection. For any serious gains a computer controls fuel mixture and spark with several sensors. My complaint is the very short spark of HEI and other electronic sparks, thus the reason for my showing MSD's on testing of points and HEI. The Hall Effect is definitely a less maintenance system, but it does NOT make a "better" spark in street RPM ranges...as proved by MSD's own testing. If 10KV ignites the mixture, 50KV is not necessary. That 50,000 volts sounds good but does not translate into better economy or more power. The little 4 has more time to charge the primary than a V8, and it has a long rod (5.2") to store energy, making good torque for its size. I raced V8's for years and got serious about 6 and 4 cylinders after I retired 15 years ago. The little motors work well if used for the purpose for which they were designed. Ford de-stroked one in the 1990's and made 600 HP, but it had to really wind the RPM's to do it. I am building a street car with an overdrive automatic to work in the 2000 - 5000 maximum RPM range. Ranger Mike, I agree spark intensity makes bigger gaps possible, and my system is definitely hotter than stock. My plug gap will probably be .035" with platinum plugs and 9 - 1 static / 7.9 - 1 dynamic compression, with my cam choice. The OEM dizzy was a hall-effect unit that used the Ford Duraspark computer, which I do not want. My 6-cylinder 65 Mustang has a Pertronix replacing the points, but I see no gain in any way...except maintenance. Just like a 30 caliber bullet, once it leaves the barrel it has no idea what launched it, but it does feel velocity and resistance. I am also a retired gunsmith who had my own gun range for 21 years. Like that bullet I wondered if the spark from a points system was actually less effective than the newer computer spark, and if so...what is the proof? THAT is my question.
 
  • #7
charlie
the hi tech spark is better at burning the air fuel mix than the old point system. it is a winner from environmental outlook which i could care less...it will make more hp on a miniscule scale but in my opinion, not worth the extra dollars. For dependabilty, the electronic boxes are more durable..but..take more battery juice to operate and quit once the battery is less than 9 volts.
 
  • #8
Mike, I can't find proof electronic spark is "better" than points at what I call normal RPM. Even MSD's testing did not show their system was better than points. All the way from idle to over 5000 RPM, points/HEI swapped the most HP position back-and-forth. At racing revs it is better at higher RPM. Racing is not in my future with auto-overdrive, air cond., nice sound system, and added insulation. My Mustang 6 points are set at .025" with plug gaps at .038" when used. Most of the time Pertronix is run. I really started a bigger debate than I expected, with this points thing. If electronic ignition can be proved to be better than a HOT points system, I would run it...but I can't find technical proof for it. No one has shown me the difference in Spark Length between the two. including MSD's system. A longer spark is more likely to ignite the fuel-air mixture than a short one...even a hotter one with multiple sparks. Those many sparks are not the same as a long single spark...AND THAT IS WHAT I AM TRYING TO FIND OUT. My research on-line, Peterson publishing books, this forum, and my own limited mechanical/electronic knowledge does not give "Spark Length" in their info. That is why I asked.
 

Related to Spark length of a points ignition compared to an HEI system

What is the difference between spark length of a points ignition and an HEI system?

The spark length of a points ignition refers to the distance the spark can travel between the points in the distributor. In an HEI system, the spark length is determined by the distance between the rotor and the distributor cap.

Which system has a longer spark length?

An HEI system typically has a longer spark length compared to a points ignition. This is because the distance between the rotor and the distributor cap is usually greater than the distance between the points in a points ignition.

Does spark length affect engine performance?

Yes, spark length can affect engine performance. A longer spark length can lead to a more efficient combustion process, resulting in better engine performance and fuel efficiency.

Why do some older cars still use points ignition instead of HEI systems?

Points ignition systems were commonly used in older cars because they were simpler and cheaper to manufacture. However, they require more maintenance and are less reliable compared to HEI systems.

Can spark length be adjusted in both points ignition and HEI systems?

No, spark length cannot be adjusted in a points ignition system. However, in an HEI system, the spark length can be adjusted by changing the distance between the rotor and the distributor cap.

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