1971 Ford 429

[Thatch]

So I've done a ton of work to my 429.
Replaced stock heads with anither set of stock (DOVE C) heads
Timing chain
Edelbrock intake
AVS2
Plugs wires etc.
Distributor
Runs excellent for a day or two then it starts to stumble, sometimes backfire, stall, then today just wouldn't start.
Then when I take the distributor out and put it back it at tdc, it starts and runs fine.

This was happening before I did the timing chain but it was worse.

Does this make sense to anyone?
Is my new distributor bad? Why does it seem to "run itself out of time '? That's what it seems like but not sure if that's a real thing

 

[TNDLB]

check roll pin that holds distributor gear in place to ensure gear not turning on shaft.

 

[Thatch]

Thanks I'll check...

 

[Thatch]

Is it possible that the pin is not sheared all the way?
Because when I take out the distributor and reinstall it, the engine starts and runs fine

 

[Fellro]

Check the timing advance to assure it isn't sticking. Also be sure you set the base time with the vacuum advance disconnected and plugged.