Incorrect timing on pulley of 53' Mercury

[Merc Cruzer]

Normally I adjust the timing on the engine by vacuum: adjust the distributor to get highest vacuum then back off slightly.

Recently, I have been chasing gremlins in the carburetor (over rich), and hesitation when acceleration from a stop.

I set the dwell with a meter, rather than feeler gauges.

Decided to set the timing with a timing light. The dot on the top of the pulley is 2 degrees BTDC. So to set the initial timing, I was informed that I should start 1/4" to the right of the dot. I reset the timing accordingly and the car ran but not well. When idling it seemed to be starving for air, until I accelerated, then it stumbled and cleared somewhat, but still didn't run well. The carburetor had been marked by the prior owner with a notch matching the hold down bracket. I rest the distributor to batch the marking and the car ran beautifully, with no hesitation on acceleration or issues of starving for air when idling.

Now here is the issue. The timing when the car is running well and using the marking on the distributor, is 1 1/2" to the right (advanced) of the dot on the pulley. What would account for this?

The # 1 plug wire is at the bottom (6 o'clock) on the distributor. This is is a stock/original distributor. The timing light is a Sears/Penske, from the 70's.