hi guys, i'm portuguese and i have the same project to my car, i have a citroen bx 87 (it's not a datsun) but i need to tune up my ignition system to a multiple coils systems 2 or 4 coils but i need to konw how i construct one electronic distributor. i think if i use a hall sensor to determinate the tdc i need to use another sensor to determinate the point each spark, sorry the english.... maybe another sensor in flywheel? i hope you understant....

Well guys, here is what I have come up with.

The easiest way of doing this multicoil thing is to get something like MJLJ
http://www.autosportlabs.net/MJLJ_V4_vehicle_installation_guide
And get a Ford EDIS system from Ebay.
well this is what I am going to do!

would a 13b cas and ecu do the trick for a 4 coil setup??

If you have 4 ignition outputs you could use some of the coil on plugs off a late model Daihatsu these have built in igniters so no need to run ignition modules, just run each ignition output from ECU directly to each coil.
A bracket would have to be made to suport the coils on an A series.
This way you eliminate additional wiring,modules and plug leads giving you a neat reliable and very effective system, and probably cheaper!!
The dwell setting for these coils is 2.5ms at 12v.
An easy way(but not he neatest)is to braze 4 pins directly on the front of a standard A series crank pully comming out about 10mm past the fan belt so the sensor has plenty of clearance just machine 4 indexed grooves each at 90 deg and sit the pins into these grooves when bronzing into place, file or turn down the pins to the same height.
there is spare boses on the block at the side to mount the sensor bracket.

Use the standard dissy (gutted and locked) with one trigger pin welded to the shaft at the original points cam. then mount a second sensor through the outside of the distributor body for the pickup.
The little bit of play in the cam/distributor gears doesnt effect timing accuracy because the dissy mounted sensor is only so the ecu knows which pin on the crank pully is no one cyl. The pin location on the pully is crittical.
Crank index position will then have to be set up in the ecu to have the pins electronicly lined up with TDC.

For single coil applications running batch fire injection the ditributor sensor is not required but the dissy cap and leads will have to be used. The shaft is still locked.You still get full ignition and fuel control but not individual cyl ign or fuel trim.

Hope this can help a little.

Dodgeman

From what I have researched into this, its as diffcult as you have described. (ie not at all)
Using the distributer to tell the computer where the crank is is the eaisest way to make it happen. Using magnets on the flywheel/crank pulley are less accurate/harder ways I think to achieve multi coil setups.

I dont think that there is enough parasitic loss thru the distributer to be able to be measured, let alone be concerned about, so just use that as the signal mechanism, and Bobs your uncle.

The most expensive and difficult part will be getting a custom dissy cap made up to look shiny.

Although using a wasted spark system with commodore coil packs does look like a tidy and clean way to achieve the same result.

With the coil on plug setups from later cars, are the coils setup to work with a specific plug type. ie special output voltages or special signal voltages? or are they just like every other coil in relation to signal voltage, discharge voltage etc.

I have done some research into ignition advance.

Here are my findings:
http://www.gill.co.uk/products/digital_ignition/Introduction/9_ign_advance.asp

Our dizzys have weights in them to provide mechanical advance as well as the vacuum advance for low to mid throttle. does anyone know if we attached the CAS from a CA18 to where the rotor sits whether we will still get the factory ignition curve from factory??

If this engine in Reuby's picture uses a computer to run both the fuel & spark, [as it must] then vacuum advance to the distributor would be un-necessary. Just run a vacuum line from the plenum or the correct port on the throttle body to the M.A.P. sensor in the computer & map the correct curve on a dyno. The T.P.S. & measured rpm will tell it when it's idling, so it will go back to the proper advance for that, no problemo.
Easy peasy. [he said as if it was done as easy as a snap of the fingers.]

If I remember rightly, my Haltech brochure says that it will accept many different inputs for ignition trigger, including the original points. [Bad idea] I presume that I could simply use my Pertronix conversion, remove the vacuum canister & lock the advance plate, then lock up the bobweight advance function to make the timing work without it wandering all over the place. [If I was to run a multi coil pack that is]
A custom billet cover to replace the distributor cap & it's all good.
Now where's the fly in that ointment? [There's bound to be one]

well. Im not using vaccume advance on my injection setup. it revvs fine....no better than with the advance. i figured that u need an ECU for the running a custom advance curve. wonder how well it would run with a static advance??

yeah thats what im talking about, except replace the coils on the strut tower with coil on plug setup

Good find Retal052! I have a CA CAS sitting in my shed, might look into it.
I wish some one could right up some thing for wiki.

The output from the computer still uses the ignitor, but you're right about the CAS triggering the ignitor. I dont know how you'd use vacuum advance without after market comp???