Car shuts off when put in drive
My 69 Dart with a 225 used to do exactly that, wanting to die when put in "D", through many years and carbs, even after a new long block. I finally tried another carb and it suddenly ran perfect. Must have been many poorly rebuilt carbs out there (that was 1994). I think that is a sign of idling lean. It also wanted a lot of advance, even to the point of wanting to surge in "P" as the centrifugal advance came on, which I think is also a sign of lean.
My 273 showed strange problems recently, first time running on a new 2 barrel carb. It would start and run fine for 20 sec, then suddently switch to running bad and die. Waited a minute and it would start right up and repeat. I found the float setting was way off so the bowl was over-flowing into the throat. I suspect the tab got bent when the box was dropped in shipping.
For comparison, I also have an electric fuel pump, with an in-line Holley pressure reducing regulator, set at 5 psi. For testing, I cranked it to 9 psi and the needle held fine. I tested the level control with the ignition off and the top of the carb off so I could see the "toilet bowl fill" operation. I set the float level with a ruler.
I won't even go into my prior screw-ups where I found it was overflowing from no needle which I must have dropped when plumbing the lines, subsequent strange dribbling into the throat which was due to installing the needle backwards in my haste to get it running, plus the rotor 180 deg off (checked it, but after playing with phasing must have lost track). I hope I didn't wipe the new cam during all this screwing around.