Not quite 180°. The Start pickup is slightly advanced compared to the Run pickup.

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一期一会
Too many people who were born on third base actually believe they've hit a triple.

Ever so slightly, perhaps within the range of gap adjustment. What has me scratching my head is why the second pickup.... if the distributor controls all advance, what on earth is the other pickup used for?

No, sir. Gap adjustment doesn't affect clocking of the pickup, and the Start pickup is advanced by several degrees relative to the Run pickup.
Same function: provide advanced timing during engine cranking (during which neither the vacuum nor mechanical advance is working).

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一期一会
Too many people who were born on third base actually believe they've hit a triple.

If the dual pick up is paired to an H.E.I module, is the second pick up doing anything? How so? How is the choice made? By the module?

Dan, would you like me to send you the distributor Jerry prepared for me? It would be worth the shipping to get an inspection/understanding. I'm not building a race car at this time... just a convertible cruiser, so I am using the single pick up distributor I have.

Maybe I'm looking at it wrong, the pickups look to be directly across from each other and aligned with rotor teeth on opposite sides.

Perhaps there's an unknown HEI module with multiple inputs?

Relay switched the pickup coils

Yes, providing the signal during engine cranking.
No, it's according to the position of the ignition switch. "Start" cuts in the Start pickup and cuts out the Run pickup. "Run" cuts in the Run pickup and cuts out the Start pickup.
Interesting idea. How much of a hurry are you in? Busy time of year for me at work.

I am inclined to think the fatter (or hotter) spark Jerry talked about was wishful imagination, and the better ET was probably a function of what happened to be an advance curve more optimal for his car in the one distributor than in the other.
I'm sure they do...but remember, a degree isn't much, visually. Neither are two or three degrees.
No. Remember, HEI was never factory equipment on a Mopar; it's a GM ignition system. There's no Mopar ignition module with dual inputs, either.

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一期一会
Too many people who were born on third base actually believe they've hit a triple.

Neat, ok so a relay does the change over. The single coil EI system seemed to work fine for many years before. Did something change that made starting harder, requiring different start timing ? Perhaps emissions related.

I'll agree that hotter spark bit doesn't make sense. The pickup itself has nothing to do with how hot the spark is. It just tells the module when to fire.

Thanks for the diagram matv, that made it clear.

what if he had 2 HEi modules and 2 coils running, one coil firing
2 degrees after the first one?

Trigger happens when sine curve flows from on side of zero to other. This happens twice, once rising and once falling. one side or the other has a steeper slope. With wires hooked up wrong, trigger is happening on the gentler slope, and signal is not as crisp.

Appreciate the explanation for the dual pick ups. Such things are computer controlled in modern engine mangement systems.
Sam

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Yup.

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一期一会
Too many people who were born on third base actually believe they've hit a triple.

Building a dual HEI system would be a lot of unnecessary complication. A coil normally fires one spark plug and I think you would have to add a 2nd spark plug for the 2nd coil.

I think you are trying to make the 2nd pickup analogous to dual points. Dual points were a crutch that allowed more coil saturation at higher RPMs for high performance V8 engines.

The beauty of the stock GM HEI system is that the built-in current limiter (5.5A) allows its matching 0.5 ohm coil to be fully saturated in 3.4 ms. On a 6-cylinder engine, 3.4 ms between sparks corresponds to around 5035 RPM.
http://www.pontiacpower.org/HEI.pdf

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1965 Plymouth Barracuda,
225 engine, Quadrajet, HEI, Dutra Duals, 904 Torqueflite, 2.76:1 axle, Addco front bar
Rods & Relics - Fort Erie, ON / Collector Car Tech

Frank I don't think anyone was trying to actively do this. Just an exercise in thought about how this fellow setup the dual pickups with hei.

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matv91, elsewhere in that service manual it will describe the reason/function of the dual pickups.

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一期一会
Too many people who were born on third base actually believe they've hit a triple.