360 stalls on deceleration from throttle blip

AJ/FormS said
Here's the scoop
If you are reading the idle timing at 12* with the Vacuum advance hooked to full-time advance ........ Then, when you slap the gas pedal, the manifold vacuum drops towards zero, which instantly retards the vacuum advance timing towards zero.
Suppose your V-can has 14* in it, and you set the base timing to 12*. Then when the VA drops out, you only have MINUS 2 degrees, equals 2 degrees retard, as the engine is taching up. That is awful. That means the timing at the slap is gonna be roughly 22* retarded. and the engine will not only not make power on that, it will not even burn all the gas in the chambers, but the burning will continue in the exhaust system, which I see is log-manifolds. Now If that happens, the logs will become pressurized. Remember I talked about a restricted exhaust? Well, there it is.
But it doesn't stop there. In your case with a pressurized exhaust, the piston has to physically pump the exhaust gasses out. AND, whenever an exhaust valve opens, while operating in this mode, and, the pressure in the log exhaust is greater than the pressure in the cylinder, then the log-exhaust is gonna enter the combustion chamber. If by happenstance you have a cam with a generous amount of overlap, then, on the overlap cycle, that pressure is gonna find it's way into the Intake Manifold, and from there, it is gonna be sent to another cylinder which is on it's intake cycle. When all eight are operating this way, how can the engine possibly continue running? It cannot and so it dies.
Therefore;
just plumb the VA to the spark-port and advance the Idle-Timing to in the window of 8>12, and let's see what happens.

Well, everything you said made sense to me so I messed around tonight. I changed the vacuum advance to the passenger side. I set the timing 10 degrees advanced tdc. My idle rpm to about 800-850 (the carb screws to 1 1/2 turns out still need to work with those cause I wasn’t getting much rpm change in or out so possibly needing carb cleaning) and bam! The stalling out after fast blip of throttle on deceleration went away. Not only that but I did notice a considerable amount of power increase when I hit the gas. It also is idling really well. I do get some rpm fluctuations but I don’t know if that’s normal? It jumps around + or - 30. Thank you for taking the time to write all that info. When you mentioned the vacuum advance can only has a limited amount of advance say *14 a light went on in my head and it made sense. I’m learning a lot. Thanks for your patience. It sounds like some guys run off the manifold side but in my case your way for whatever reason helped my issue.

AJ/FormS said
Here's the scoop
If you are reading the idle timing at 12* with the Vacuum advance hooked to full-time advance ........ Then, when you slap the gas pedal, the manifold vacuum drops towards zero, which instantly retards the vacuum advance timing towards zero.
Suppose your V-can has 14* in it, and you set the base timing to 12*. Then when the VA drops out, you only have MINUS 2 degrees, equals 2 degrees retard, as the engine is taching up. That is awful. That means the timing at the slap is gonna be roughly 22* retarded. and the engine will not only not make power on that, it will not even burn all the gas in the chambers, but the burning will continue in the exhaust system, which I see is log-manifolds. Now If that happens, the logs will become pressurized. Remember I talked about a restricted exhaust? Well, there it is.
But it doesn't stop there. In your case with a pressurized exhaust, the piston has to physically pump the exhaust gasses out. AND, whenever an exhaust valve opens, while operating in this mode, and, the pressure in the log exhaust is greater than the pressure in the cylinder, then the log-exhaust is gonna enter the combustion chamber. If by happenstance you have a cam with a generous amount of overlap, then, on the overlap cycle, that pressure is gonna find it's way into the Intake Manifold, and from there, it is gonna be sent to another cylinder which is on it's intake cycle. When all eight are operating this way, how can the engine possibly continue running? It cannot and so it dies.
Therefore;
just plumb the VA to the spark-port and advance the Idle-Timing to in the window of 8>12, and let's see what happens.