Last time out one motor stalled while idling. Just shut off like switched turned off. Started back up and ran fine for an hour or so. Later while running on plane it shut off again. Wouldn't restart so I limped in on one motor and went home. I have no spark. This is old school 454 MkIV MSD Billet Distributors (the one which don't require the MSD Box)
Checked wires and grounds. I have power to the coil.
I swapped coils from other motor. no spark.
I pulled and swapped distributors including rotor. no spark
I've not swapped the fairly new distib cap and coil wire which is my next step after the rain stops This occurred to me while typing.
Anything else I could look for?
Thanks for reading.

Mark

Disconnect the gray lead from the tach. If the tach is bad, it could ground out the coil.

Another thought too, check the wiring for your lanyard.

Check for 12V on the + side of the coil, and keep meter on it while cranking.

Disconnect the Tach (gray wire) from the - side of coil

Wouldn’t be the 20,000 th time the msd mag pickup 0r box gave up the ghost.

Thanks. This MSD dist. don't use a box. I used to drag race and I call them red bricks and swore I could have built a garage out of them. I swapped distributors to eliminate the pick-up.
https://www.holley.com/products/igni...rs/parts/83606

Thanks Tom and Dodge for the gray wire advice. Will try. On the lanyard I don't "think" I would have power to the coil?
Thanks all

Would depend on how the lanyard is set up. Mine can be configured to break the power connection (that’s how I have set-up) or it can ground the tack wire. Assuming most would use the cut 12v side but you never know.

I wired it 12-13yrs ago LOL So you never know! Thanks again. I THINK i have the ignition switch power running thru the kill. Worth a second look.

You can remove the orange wire from the (-) negative side of the coil. place a jumper lead on the (-) side of the coil. Using a spark checker at the coil, turn on the ignition and tap other end of the jumper to engine ground. If you have spark as you tap the lead the pickup or magnet is bad in the distributor.

Disconnected tach wire (gray on neg side of coil) and checked that I continued to have power to the hot side while cranking. No spark.
Mr V8 I think I eliminated that by swapping distributors from the running motor. Just remembered the coil wire and changing that now.
Thanks for the suggestions all Still pulling hair... and a coil wire now.