67 Dart 270...Project Old School

I got some time last night to tune on the carb. Last time I drove it I was having to have it idle at 1500 in neutral to get it to idle at 800 in gear and it still wanted to die half the time. Fun times in a tight parking lot with the manual steering. Tonight I pulled the carb and checked the front butterflies and they were open so far they were well into the idle transfer slots. I grabbed a small screw driver and cranked open the rear butterflies a full turn. I mounted up the card and fired it up and it wanted to idle at 2000 rpm. I turned down the primary idle screw until it was no longer touching and it still wanted to idle at 1300.

I pulled the carb again and closed the secondard butterflies 1/2 a turn. I mounted the carb on the engine and now I was able to hit the correct idle speeds. I set the idle at 750-800 in gear. I took it for a drive and let it fully warm up. After the 5 mile cruise I returned to the garage to find the car would restart easily, but would die when you put it into gear. I upped the idle speed to 850-900 in gear but the results were the same. I then backed out the idle mixture screws 1/2 turn on both sides and it was bettter, but still died. Another half turn out on the idle mixture screws and now the engine just purrs at 850 when I drop it into gear.

The vacuum gauge shows I am pulling 12" of vacuum in gear and 15" in park. I have the distributor set at 16 degrees initial timing. If I get some time tonight I will plot out the mechanical advance timing curve. I want to shoot for 35-36 total to start.

Back to the carb, I am thinking I need to swap to a lighter spring in the secondaries (750-3310). With the stock cast pistons I will be shifting under 6000 RPM. What would be a good spring to try? Purple? short yellow?