This might be a loaded question, but what's the difference between points, dual point, HEI, electronic, etc etc distributors...?

Thanks

 

Is this a joke?

 

You obviously are...

Anyone? I'm hear to learn, not to be criticized..

 

A points system uses mechanical contacts to trigger the primary coil circuit. When you cut off power to the primary circuit, the secondary circuit fires the plugs. The mechanical contacts (points) open and close as the cam on the distributor shaft rotates. Downside to points is that they're a wear item; every time you open the points you get a slight arc, which slowly degrades the contacts. Maintenance on them is also rather tedious and must be done fairly frequently.

I'm a little fuzzy on dual points, but I believe the idea is that you have two separate sets of points that allow you to vary the dwell (how long the coil is charging vs discharging) as you pass a certain rpm range. Longer dwell at higher rpm's allows you to maintain a solid spark at the plugs. Dual-points systems are fairly rare. K codes, 65-67 GT350's, and I believe Kar Kraft cars (Boss 302 and 429) came with them.

Electronic units use transistors instead of a mechanical switch to control the coil primary circuit.Asmall blocked ring (just like the ABS ring on a modernvehicle)rotates with the distributor shaft. The rotation is picked up by a magnetic trigger whichtells the transistor to open or close. Transistors can fire millions of times a second and don't wear out like points do, so electronic systems tend to be much more reliable. More advanced units use computer control to vary the dwell across the rpm band or supply multiple sparks.

HEI is short for High Energy Ignition. It was a GM creation to improve economy by creating a hotter, longer spark. By planting a high voltage (100kV or so) coil directly on top of the radiator cap, you bypass the normal coil wire and allow a much larger voltage to reach the plugs. More voltage means you can open the plug gap up for a better burn. The downside to HEI is that there's so much extra voltage available that it can hide ignition problems until they become extremely severe. For example, probably the most common problem with an HEI unit is a hole burned through the cap. If the cap and rotor aren't inspected regularly, the coil button in the cap will burn through. Normally this would put the cap out of service, but the HEI coil supplies so much voltage that it will keep sparking straight through the cap, eventually burning out a nice hole in the top of the cap. Also, poking your hands around an HEI system can be painful. If you've got a failing wire, you're probably going to get an 80kV shock when you move your hand past it. Most stock coils are about 20kV, which isn't too fun if you've ever been zapped, but 80-100kV will wake you up right quick if you're not paying attention.

 

Thanks for the info Tad. Currently I have no existing set-up on the engineto go off of, so this is going to need everything.

Sounds like electronic would probably be the most reasonable, huh, for a moderate build?

 

I just got an HEI. you get the whole dizzy for less than an elect. ignition, off of ebay at least. I like it. definitely dont go with points.

 

HEI is a type ofelectronic ignition system. It triggers off an electronic control module located in the distributor housing. No points, just a magnetic pickup and transistors.

Most people will be just fine with an electronic conversion kit for their factory distributor, as well as an advance recurve. Nothing wrong with this setup, assuming the distributor is in good mechanical working order.

If you don't have a distributor at all, then yeah, you're probably better off with an HEI or other reasonably priced factory-style electronic setup. You'll spend the same for that as you will for a rebuilt OE-style distributor and an electronic conversion kit. I just don't really like the HEI setups because they're freaking huge. My MSD distributor istall enough to require a curved monte-carlo bar, but at least it's relatively narrow soit doesn't interfere with the air cleaner.

MSDsetups are pretty overkill for most people. Granted, I bought an MSD billet ready-to-run distributor, but that's because I wanted to be able to easily tweak theadvancecurveand to have the ability to easily add a box in the future (the ready-to-run plugs right intoan MSDbox). Most people won't see any benefit from an MSD box, though, especially when compared to how much you pay for one.

 

hiya ... just wanted to add to this.
I believe this is mostly to help you deciding what distributor to get.
Starfury already pointed out the technical details, here's the shopping advise:

Pro points:
stock. if you need your car to be stock, go with the original setup

pro electronic ignition:
everything else. If you do not need car to be stock, then go for this. Here are the reasons and differences

1. there are electronic modules that you can use to replace the points in your disttributor.
The advantage is that it still looks stock, but you'll never have the bother to replace points anymore.
But if your distributor is 40 years old, then I'd nearly bet that at least the following is fried: vacuum advance diaphragm, bearing for distributor shafft (if shaft has play you'll never get the timing right) and in most cases the humps that work the breaker contact (the 8 on the shaft) are mostly run down, which results in the same. improper dwell (different from cylinder to cylinder and ignition timing jumping back and forth). So if that's the case I would rather go for the 2nd or 3rd option

2. replace the distributor and coil with something like the pertronix flamethrower II (this does not mean get one of them, just easier for me to explain as I have that)
Basically this is a new distributor with the ignitor module already pre-fitted. Together with that you could get a new high voltage coil, which would enable you to open the spark plug gap a bit (to something l;ike 1mm), which usually results in more efficientb burn and better gas/mileage
Advantage is that it looks kinda stock (distributor seperate from coil)

3. the HEI-option. When people mention HEI, they usually refer to the GM electronic ignition. It's a HUGE distributor, with the coil right on top of it.
So you have an all in one unit. The advantage of this is: you can get spare parts for this _everywhere_. The disadvantage: if you have one of those big round hipo style aircleaners: they won't fit anymore.
And probably a few others. Friend of mine had to get one of those tiny ones that look like a birthday cake ...

In any case you should opt for electronic ignition instead of a breaker system. As this will give you:
more accurate timing, better gas/mileage and performace (depending on how bad the original distributor was. so it's only minimal)
The ignitor II modules are advanced (flamethrower II) use them as well, as they do adaptive dwell control.
The dwell is the relation of how long the primary circuit is open to how long it's closed. breaker points can't do that (maybe as starfury pointed out with the double-breaker, i don't know)
The newer modules change the dwell in relation to rpm

long story short: if you do not need concours, go for electronic.
modules are the cheapest option, but for that you need a peoper working distributor
then the HEI, which are about 150$ i think. Check on ebay or jegs or any mustang parts store
The new pertronix flamethrower distributor is ~275$, the coil at around 35$

IMPORTANT:
==========
1. if you treat yourself to new dizz, module, coil or anything. do yourself a big favour and replace old spark plugs and cabling.
2. If you use high voltage, then use 8mm+ plug leads at least
3. Don't fall for the word RACE DISTRIBUTOR. It sounds very quick and performant, but what this usually means is that tyhe vacuum advance is missing.
You do not want that on a street driven car. On a street driven car you have low to high ported vacuum depending on load etc, you need the vac advance to regulate for that.
The mechanical advance adjusts ignition timing for when you rev higher.
The reason a 'race style' distributor gets away with having no vacuum is the reason that the carb only knows one single state. throttle wide open. constant.

 

if you wanna go cheap electronic uses this wiring diagram and get the box and a dizzy and hi out put coil.

 

btw, the HEI dizzy is pretty big. you may have to re-run some lines (i had to get a longer hose for my fuel line), and if you are doing with an aftermarket intake, it may be too big.