13 replies to this topic

[Dr Terry]

That module is out of a VL-VT Holden EFI V8. With its matching distributor it is designed to work with the Delco EFI & ignition system. The distributor has no internal advance mechanism, either centrifugal or vacuum. All ignition timing is controlled by mapping programmed into the ECU.

 

Does the MSD Atomic system include any ignition advance mapping ? It looks to me like a simple throttle body injection system being timed of the negative coil terminal.  If this is the case just use a Blue/Black Holden HEI dissy.

 

A better system is something like the ICE programmable ignition system, but that might be a bit of overkill for TBI.

 

Dr Terry

[76lxhatch]

There are always ways and means but if you're not making components yourself and looking to keep it simple then yeah replacing the dizzy with a magnetic pickup unit is going to be easiest. Also nice not to have to rely on the factory ignition module.

[Dr Terry]

Where does the distributor connect in that diagram above ?

 

Dr Terry

[A9X]

how do you lock up the dizzy ?

[76lxhatch]

That makes sense, do you have the ability to change the reference angle so you can index the dizzy for best rotor to cap contact? How wide is the rotor tip, some aftermarket ones are quite narrow which might not be ideal for a wide range of timing advance.

It must come with a piece that is designed to lock it up, probably uses the adjustable advance limit/stop mechanism.

[76lxhatch]

Would be good if you can index the reference angle so the rotor tip is as close as possible to the correct post on the cap throughout the advance range (which also depends on your tune I guess, could be anywhere between 30 and 50 degrees variation). Would be good if a wider tip were available though, obviously its replaceable. Going to be doing an EFI conversion on mine at some stage and will be retaining my Accel dizzy (similar setup with narrow tip), its one of the things I'd like to improve as I know from experience it will happily cross fire to other posts on the cap if not set up right.

[76lxhatch]

Bugger, that's what I was talking about indexing - some EFI systems will allow you to change the reference angle in the computer, obviously you have to adjust the rotor manually.