which stock 4-pin hei module has more dwell...

[sc2dave]

i need 2 HEI 4-pin modules for my motorcycle. Redline is around 11,000 or so. What brand/model HEI module has the most dwell in it? this is what I want to make; http://www.geocities.ws/loudgpz/GPZheiMod.gif

[modok]

I believe the dwell is a function of the trigger signal. yeah Gm had a patent on how the dwell was variable, perhaps you could find it.
I believe it was a simple analog method, just relying on how the voltage from the pickup went up at the .....square? of rpm
So it would fire and charge the coil as the signal crossed a certain voltage.

With a one tooth wheel... Dwell will probably be VERY LONG, but you could chose a coil that will work with that.
Question is if the pickup coil will make enough juice to fire it at cranking,. or kicking? speeds. if so, should work.

[Geoff2]

The reluctor signal is an AC sine wave that is proportional to rpm. The HEI module is designed to work with the HEI pick up, which has a relatively high resistance of 800-1100 ohms [ compared to the MSD, Accel,Chrysler, etc 150 - 400 ohms ]. My understanding is that the HEI module determines the dwell using the reluctor output signal. The module knows that rpm is increasing from the increasing reluctor voltage & the HEI circuitry uses this to start coil flow earlier at higher rpms so that the ign coil has enough dwell time to saturate the coil.
Using a p/up coil other than the correct HEI p/up coil may affect the way dwell is applied because the output voltage is likely to be different.
The less cylinders there are to fire, the less critical dwell is because there is more time between sparks to saturate the coil. This is probably a 'suck it & see' situation.

[mach1charlie]

Did that on my kaw 1000 police bike, when factory igniter went out. Works great. Mounted on aluminum plate for heat transfer.

[pamotorman]

when HEI came out i was having trouble with them blowing out at high RPMs. these were aftermarket modules and it turned out to be they had no voltage regulator built in like the GM one did. switched to GM modules and no more problems

[Firedome8]

Do gm hei modules work on the current limiting principal clamping pri current at 5.5 amps and set the dwell accordingly to the point it turns the pri on at end of spark line. just thinking
https://youtu.be/vOmPW-ze3Tc

[Tuner]

http://gpzweb.s3-website-us-east-1.amaz ... .html#home

[tjz450]

The old factory GM module stamped 990 is the best one, can only be found used or NOS. They say it has a dwell stretching feature. I like to believe they are better than the Asian built clones.

[Truckedup]

A good high performance module should have a dwell limit at lower RPM's to preventing heating up the coil necessarily...

[DaveMcLain]

It seems like to me that you won't need any fancy model just a stock GM/Ac Delco replacement module. Those have no trouble going to 7200rpm with a reasonable plug gap in a V8. How many cylinders do you have on your motorcycle? If it has four cylinders that's 14,400rpm.

[BigBlockMopar]

Why limit to 4-pin modules?
7-8 pin modules, to my knowledge, have a higher possible amp throughput and you can leave the extra 3-pins unconnected.
Although I'm not sure how much of its improvements are lost when it operates in bypass-mode all the time.


I've been using a 4-pin module in my converted Mopar ignition system.
After I burned one out in a heavy traffic jam I swapped over to the 7-pin module with the 'extra' 3-pins unconnected.
Currently I'm running the same 7-pin module hooked up to the MegaSquirt ECU which controls timing and dwell through it.

[Schurkey]

Wow. So much to say, and I'm rusty at this application of the HEI module.

I have the parts to do this on my Honda, but haven't installed them...yet.

1. The HEI pickup coil signal is NOT a sine-wave. It's assymetric, where the voltage builds from - towards + relatively slowly, but goes from peak + to - very suddenly. This is intentional, because it makes the trigger "non-mistakeable" to the module--the plummeting of voltage on the + to - swing.

2. The module uses the second pickup coil wire to bias the voltage in the pickup coil windings. The first terminal senses enough voltage to turn on the coil dwell, and of course the module ends the dwell period when the pickup coil goes from + to - triggering the spark. The big deal here is the module varying that bias voltage through the second pickup coil pin/wire, which is what changes the dwell time. On the Honda application, there are problems with this feedback because of the long time between reluctor/pickup coil pulses. If you can get the engine running, it'll be OK, but it's hard or impossible to start without some trickery to the bias circuit.

3. The GM/Delco modules are all Asian now. (Singapore, last I looked.) They still seem to be as good as any other; and I'd bet that the same factory is making the best of the aftermarket replacements--Echlin, etc.

4. GM has a THREE-pin HEI module, which probably does not have the pickup-coil bias and therefore no variable dwell--and variable-dwell problems. I'd like to study one someday.

I'm going to have to research all this again soon. I'll post a link to the main thread about this in the 1100F forum, which is where I learned about it to begin with.

[Geoff2]

Shurkey,
The output from the pick up is a sine wave, AC. Inside the module, it is converted to a square wave signal. This is from GM's description of the pick up operation: "The voltage signal coming from the pick up coil is alternating current....Inside the module is a converter that changes the voltage to direct current & a square wave".

Also, MSD used to have a tech page on their website showing the difference between magnetic & optical triggers. The mag trigger is shown with an AC sine wave.

I think you may be confusing the output voltage wave shape with the flux wave.

[Truckedup]

i need 2 HEI 4-pin modules for my motorcycle. Redline is around 11,000 or so. What brand/model HEI module has the most dwell in it? this is what I want to make; http://www.geocities.ws/loudgpz/GPZheiMod.gif

Are you looking for a lower cost module replacement or expect a performance increase? I assume the Kawasaki uses a mechanical advance unit?

[user-23911]

,
The output from the pick up is a sine wave, AC. Inside the module, it is converted to a square wave signal. This is from GM's description of the pick up operation: "The voltage signal coming from the pick up coil is alternating current....

Just because it's AC doesn't make it a sinewave.
Same as a magneto, it's not a sinewave.


But anyway those 4 pin modules are usually just an amp with current limiting.
There's a diagram on line to show how to use with points. Just a pull up resistor required.
The output follows the input.