DIM Electronic Advance Ignition

KitCarlson said

The GM 8 pin module is not a controller. It is a VR interface with dwell control and current limit, all this is analog circuitry. There is not a micro-controller inside. To add a timing controller is possible, but using it on a mechanical advance distributor would be silly.

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I think the GM 7 or 8-pin module does have some smarts in it. Probably not a microprocessor, but dedicated digital circuitry. As I recall, it outputs a square wave which an external spark controller can return with a delay to set the desired spark timing. This is similar to the Ford EDIS module but a different input (distributor, not 36-1 crank wheel) and a single coil output.

Several after-market ECU's can interact with the GM 8-pin module. The Holley Commander can connect directly w/ optional cables.

I don't think a timing controller with mechanical advance is silly. The controller just adds to the mechanical advance. This has the advantage of allowing a fairly accurate "limp home" mode, as well as keeping the rotor tip better phased to the posts, plus requires no buggering with the distributor. The disadvantage is that the weights can stick and be erratic, but if your controller is constantly advancing to a knock limit, that "comes out in the wash".