Direct coil vs. Edis unit

[Bluehaze]

Hi all. I'm currently in the fine tuning stages on my Holden. Right now, I'm running with a VR pickup in the distributor and driving the coil direct. This system works well, but I'd like to know if it's worth going from direct coil driving to driving the 4-Pin Bosch HEI transistor unit with the existing coil driver, (with an appropriate pull up between the +12v and the signal) and driving the coil with the HEI unit. Three reasons I'm considering this:

1- Provide a level of isolation between the MS and those nasty voltages present around the coil -I'd hate an errant spark to fry my daughter board! -I'll hasten to add I've yet to hear of this actually happening.

2- Trying to eliminate all sources of noise in all the other signals coming back to the MS unit

3- Less wire in the coil circuit might make the driving of the coil "snappier".

Thanks for your help to date. You guys on the forum have been my only contact regarding the whole MS experience. I kinda hoped that once the car was running well, I'd sop tinkering. -yeah right!
V3 board running 2.905
Tuning with registered TS and Logger - Well worth registering!

[trakkies]

I had the same setup as you but on an RV8 for some time and it worked tolerably well. However, I now have EDIS which gets rid of the dizzy. My thinking being a dizzy sensor (dizzy gear driven off the cam, which is in turn driven by a chain) ain't going to give as accurate or stable timing as a crank sensor. And, of course, rotor arms and caps can cause problems.
If I were doing it now, I'd have to think about using actual EDIS, or doing wasted spark from MS using extra coil drivers. But I'd site those coil drivers close to the coils, not MS, for the reasons you give. If the design of your engine allows it, I'd consider COP with built in ignitors - not really practical on the RV8 due to the plugs being so close to the exhaust manifolds, and the heat from that.

[Bluehaze]

Thanks Trakkies.
Once again I started with a simple plan, and now the power of suggestion has had me read up on EDIS. So now youve whet my curiosity I have read up on the concept of EDIS and I'm well impressed! Although the distributor setup I've got produces a rock-steady timing mark through the strobe, it does get a little jumpy when I pick up the revs. In the case of the inline six, the cam gear has almost zero backlash as does the geared coupling between the camshaft and cam gears. I assume the SAW signal can be driven via the existing direct coil (BIP373) and a modest pullup resistor. I will have to go away and research the idea of the COP/EDIS/wasted spark control for my setup. I still might try running the HEI module in the meantime, as the noise thing is still an issue I'd like to minimise-like you said- coil driver close to coil.
My first priority for now, however is plumbing a cold air intake system, as the under-bonnet air has my IAT sensor reading up to 70deg.C. (only a mild 30 degree day)- and summer is coming.
Like I said, I thought the tinkering would stop

[trakkies]

EDIS uses low volt signals both in and out, so you don't need the high current ignition driver in the MS. Just follow the instructions in the manual.

FWIW, there is always some backlash in gears. A crank mounted sensor, not.