Twin Plug Distributor Ignition Advance
 

When im looking at Twin Plug distributors for sale, be it used ones or new, I never see anything about what advance curve profiles they are specced to. After all they are made for all different sizes and specs of engines.

How is this so? Are they all made with a generic curve? or are they fixed with no advance?

How do you go about tuning ignition advance on one of these? or is it assumed you have some kind of programmable system like a CDI+, and the distributor doesnt do the advance.

thanks again!

Traditional method:
https://www.racingjunk.com/news/performance-tuning-your-distributor/

Modern method:
Changing numbers in a table in the ECU.

They are set by the builder and they often claim that this info is proprietary. Honestly it isn't rocket science, but you do need some special kit to do the job.
My PMS dizzy has 18-20 degrees of advance, I'd have to check but IIRC I start out at 8* and max out at 28* @3500rpm (likely 3000-3200-ish RPM) total advance. Runs very well for a street car, no complaints.

A programmable CDI you have to lock out the advance, but you have to be careful of the phasing. Some rotor/cap combos will have trouble with this. I don't know anyone that sells a programmable TP dizzy.

Cheapest twin plug ignition would be to do the Megajolt Jr crankfire using Ford EDIS ignition parts, or you could run a MS as ignition only.

Need engine specs first to establish a rough baseline. If compression ratio is <9:1, something like an early S spec ignition advance curve (see repair manual). To squeeze max. power/torque, suggest dyno-testing. A knock sensor system would minimize the chance of engine-destroying detonation.

Sherwood