What's a heat sink if you don't mind explaining it to me?

 

It's a place where you wash red hot items.

Welcome to Instant Rimshot

Heat sinks are those finned pieces of aluminum that passively dissipate heat from (usually) solid state electronics.

 

It might be simpler, but it disables (deletes, really) the retard on start that the DS II and the TFI has. It works, but not as well as the stock ignition. Besides, you have to cobble wiring into the truck, and use GM parts to boot. It might work, but it isn't my cup of tea. I'm glad you like yours, though.

 

Well I don't have anything against using GM parts if they work but, would be nicer if there was a "clean" way to install it. Wiring isn't a big deal to make neat but would take some work to make it the HEI look stock. Maybe figure out a way to mount it in the dizzy like the DUI but with the coil separate. In my Jeep background I have used the HEI on several motors and it's a great setup. Easy to repair and cheap. Carrying a spare is cheap insurance.

 

Okay hey guys how's it going so I was looking under my hood and after I convert it do I rip the computer and all the wires with it?

 

For what it's worth, there's a great site that will tell you how to convert to high energy system for dirt cheap: www.gofast4less.com

His system, using the GM 4 pin module, gives you (what is the name of that high dollar aftermarket dizzy?) one of those for next to nothing.

 

Sorry to bring up an post but it looks like this may be the one I need.
I put an 84 460 into a 93 chassis and have removed the ECC and really don't want to mess with this DSII conversion with the 2 pos wires and resistors and relays. I have the DSII dist and coil on the motor and want simply. Will this link Better Dirt Cheap Electronic Ignition work straight forward with my setup. This is a work Dump truck with 4.10 and 4 speed so power and torque are what I am looking for.

 

Use a volt meter to check the voltage from the ignition switch. There may already be a resistor wire in the harness. My '86 with a feedback carb has the correct voltage, so there's a good chance your vehicle might as well. If you're getting ~9.5v with the ignition on the DSII conversion is plug and play.

 

Baron, after 86 the DSII coil resistor was in the underhood harness on the 351 4V and 460 engines, everything else was EFI. After 91, the ignition switch changed doing away with the dual feed for ignition. DSII uses a second power source during cranking and returns to the primary source for running. A pre-electronic ignition coil resistor can be used instead of the Ford resistance wire. I build a relay operated circuit that emulates the ignition switch function so I can use a 93 front harness (currently) and still have my DSII and carburetor. I built mine using a cut off piece of 92 up engine harness so it would plug into the 42 pin square connector for the engine.

 

This is a great thread, thanks all for participating! I've read most of the linked articles and they are a wealth of information.

I'm putting a Duraspark dist. in the 73 in my signature, but I can't for the life of me find a DSII box or harness in my local junkyard. I was thinking about using the GM 4pin and mounting it in the cab up under the dash. I hope you guys don't mind helping me understand and tolerating a couple questions. Most of the GM 4pin install threads here on FTE degrade into bickering and personal attacks, but this thread is different. You guys really seem to know what you are talking about, so I hope you can help!

I found a great article HERE (direct .doc download) explaining the inner workings of the HEI module. It is absolutely a must-read.

In the image above, it appears that the coil and the module would be getting full 12v form the ignition switch. This matches the article that says: This also meshes with what I've read on THIS SITE (Its a Pontiac, but its points to 4pin so its valid) but I'm seeing you guys state 8v, 8.7v, 9.5v and "less than 10v" is required. The ignition in my 73 should have the "pink wire" feed for the coil positive, dropping it to somewhere in the 7~8v range to work with stock points ignition, just like the Pontiac above in stock form. It "works" on 8-9v but it seems like there is a lot of "power" left on the table if running at less than optimal (stated 10-15v) voltage. I also tend to wonder how much additional stress/heat is generated inside the module when running 2-6v low. This could easily be remedied by using a relay for full 12v power, as seen HERE and as discussed HERE:With regard to coils
Running with no current limiter and no dwell reduction is going to cook the wrong type of coil in short order. I'm wondering if running the HEI module & coil @ 8-9v is a band-aid to help with longevity, possibly to make up for using the wrong type of coil? This would explain why everyone recommends a lower supply voltage? What is the primary resistance on the "square coil" you all are using?

While looking for stock GM HEI coil info, I found this: The site for the above can be found HERE. A combination of low input voltage and high resistance coil is going to significantly cut spark energy, or the super long charge time at low voltage through the module is going to make a whole mess of heat. This may explain why people have been having issues burning up modules and coils. I have a stock points coil (I should probably measure the resistance) a PerTronix 40011 1.5 Ω coil and a MSD 8222 0.7 Ω coil at my disposal. In theory, choosing a coil should be a no-brainer. The PerTronix would work, but the MSD would be better as it more closely matches the GM stock .5 Ω coil that the module was designed to work with.

Sorry for the long post, I'm just trying to make sure I understand exactly what I'm doing. If you guys have the info, could you post up your coil primary resistance, what voltage you are seeing at the coil, and how long you have been running this way?

 

I don't have a multi-meter handy, nor the car....
But, I am feeding the full 12V current to 3 X GM HEI's and 3 X MSD blaster 2 (8202) coils on my rotary. All 6 are powered from a single relay, triggered by the original ignition power wire.
The only issue I've ever had was all 3 HEI's failed almost simultainiously, due to excessive heat. The guy that I got the car from used a piece of 22 ga sheet metal to mount the HEI's. I replaced that with a piece of 3/16" stainless and artic silver 5 CPU paste, and upgraded to a better brand HEI.

The MSD coils on mine appear to have the same 0.7 ohm primary resistance, according to the specs I've found online.
All I can say is this, the ignition system can certainly handle trips to well over 7K RPM........

 

That's exactly the kind of info I'm looking for, thanks! I believe that's the way HEI equipped GMs are wired from the factory, been doing some google searching to try to confirm.

Warning: rotary question
What is the duty cycle for each module in your rotary application? I don't have the brain-brain today to even begin to try to figure that out... With the v8 and a single coil, 4000rpm / 2 / 60sec X 8cyl and I'm looking at 266.6 spark events per second (unless my math is FUBAR.) Not a whole lot of time for dwell! How often does a rotary use each module per second?

 

You asked for it......
The rotary fires all 4 plugs (2 per rotor) every rotation of the shaft, however, the way I have mine rigged up, 2 of those plugs fire every 1/2 rotation, for 2 per rev, but those 2 plugs have their own HEI and coil. The other 2 plugs share a HEI/coil, and are run thru the stock dizzy to separate the fire.
At 6000 RPM, each coil fires 12,000 times/minute or 200 times/second. The exact same number of cycles/second as a standard 4 cyl at any given RPM, and only 1/2 of the cycles as a V8 at the same RPM. (note, the 4 cyl and V8 comparison assumes a single coil setup)
As you can see, 8000 RPM on a rotary isn't asking the coil or HEI to do any more work than 4000 RPM on a V8. I just have 3 of each, but only 2 magnetic pickups to trigger them. 1 pickup triggers 2 HEI/coil combos, and those coils are hooked directly to the plugs, 1 coil, 1 wire, 1 plug. This gives me 3 sparks per rev, per rotor.
It sounds super complex, but it's really pretty simple. Complex comes with trying to explain how a 600 CFM isn't "too big" for an 80 CID (1.3L) engine...... In fact, it's borderline too small. Rotary VE can exceed 125%, even in non-boosted form. Prolly has something to do with no valves stopping/starting the flow of air. When 1 rotor face has finished drawing air, the next starts drawing instantly, so the velocity remains at peak levels.
Interesting little critters, with only 3 moving parts....... And 30 tiny metal pieces to take the place of piston rings, each with their own spring, any one of which can really ruin your whole week, and engine....... And bank account......