ChainHartMachin

Could the Cadillac Northstar DIS ignition conversion be put onto carb'd cars with stock 4-pin HEI systems? I was looking at the 4 pin HEI module (and a block diagram of the underlying electronics) and it seems like if the coil primary output was inverted (high when charging rather than low) and connect to the EST pin, the Northstar DIS could be controlled by a vac / mechanical advance distributor. As long as some parts were sourced from the salvage yards, this could be a low cost alternative to aftermarket crank triggers (potentially even better assuming the Northstar module handles its own dwell).

My own costs have been roughly:
$28 for a wheel
$25 for an ICM and coils with wiring harness connectors
$18 for a slotted bracket similar to aftermarket crank trigger brackets
$20 for a bracket that allows installation of the ICM to either valve cover (perimeter bolt).
$30 for 2 New crank sensors (could be significantly cheaper at the JY)
$10 for 1 foot of aluminum rectangle tubing to make sensor brackets
$10 for misc washers, spacers etc.
$10 for components to make a level shifter circuit for the tach

So $151. An MSD crank trigger kit costs $250 and you still get to buy a crank trigger distributor on top of that (although I suppose you could try connecting the crank sensor to the pickup coil inputs).

I don't know if something like this would have any functional value in a carbd car or not (except for generating some confused looks at shows/gatherings). I'm mainly interested in seeing if it would work.

Six_Shooter

iTrader: (2)

It sounds like you want to use the reluctor in the dizzy to trigger the N* ICM. That won't work. The N* ICM needs the matching trigger wheel and at least two sensors to make it work.

If for whatever reason you wanted to keep a carb and use DIS ignition, you'd be better off using a MegaJolt or MegaSquirt in ignition control only mode.

ChainHartMachin

What I would be doing is use the NorthStar wheel, sensors and ICM so that the Northstar module by itself has 10 degrees ignition timing. I would use a stock 4 pin HEI module to generate a signal for the EST input of the North Star module (which looks for a high-to-low transition to turn off primary current to a given coil and fire a spark)

The_Punisher454

You still depend on a distributor with your plan. Personally I'd just use a dummy distributor to turn the oil pump. You can make a shorty on a lathe REALLY easy(I just did one myself). Then use an ecu for timing only.

ChainHartMachin

In my setup now I'm using the stock MAF TPI ecm to control the Northstar module. I wrote this post as much as anything to validate whether using a vac / mechanical HEI to feed the EST signal to to the Northstar module would work. I agree that it would definitely not be optimal to do it this way. My thinking is that the Northstar ignition module/coils would be an improvement over an HEI/single coil even if the EST signal came from the vac / mechanical advance distributor and it would cost less than an aftermarket ignition box. Removing the distributor all together and using an ECU would be better, but it does add cost and complexity.

RBob

iTrader: (1)

I don't see any reason why it wouldn't work. As you mentioned use a level shifter to provide the proper 5 v square wave for the EST. And be sure to hold the EST/BYPASS line high (5 volts).

The only tricky part would be getting the distributor set to provide the proper 70* timing angle for TDC.

RBob.

Six_Shooter

iTrader: (2)

That's where an RPM activated switch would be needed.

Set the dizzy at the 70* TDC. Use an RPM activated switch set to around 400 RPM, to enable the 5V on the bypass line, and it would be similar to how the ECM control would come in.

Better yet, I would use a MegaJolt and forget about the dizzy completely, much more tunability, likely to be less work, and cleaner install.

Also with MegaJolt, you could use Ford EDIS, which is a simple wheel of a 36-1, that can be found in the aftermarket as universal wheels, modules are somewhat easy to find, and easy to retrofit because of the aftermarket support.