Will this work?

I'd like to use the same power wire that energizes my nitrous solenoid to bring power to the white cranking spark retard wire on a blue duraspark box (obviosly with a diode so as not to energize the starter solenoid) this SHOULD give me about a 6 degree spark retard as soon as the nitrous system is turned on.

I'll probably be using a 50-100hp shot plate system (like a edelbrock 70001) under a small 4bbl,

 

I am not sure how accurate the spark retard function is on those units. I have heard clear up to 20°. It may also vary from unit to unit but you could sure rig up a test with a timing light easy enuf and check out several units. Lock out your vacuum advance and mechanical advance then switch leads with a toggle switch while the engine was running.

I suspect they may just use a R/C timing circuit for that function. With cheap timing components the amount of retard may also be very temperature dependent. It would also be RPM dependent, remember they are designing for cranking speeds. Precision R/C timing components are $$$. You could also use a hair dryer to check temperature effects. Just don't bake the box tooooo long.

By the time you do the testing to make sure you don't scatter an engine it may be cheaper and faster to just buy the commercial stuff. I know you like playing tho... -Have fun!