My 1960 Corvette 283 with WCFB will not idle unless it is just about fully choked and then while at idle pulls about 18 on the vacuum gage. When I open the choke more than about 3/16" it dies. I've checked the intake with propane at every gasket and jetted propane under the manifold through the vent pipe opening next to the distributor and no leak is evident. I thought perhaps it was a carb problem so using an adapter I put on a good 2 barrel with the same result: When the engine is fully warmed up it stalls unless choked.
Background: I just replaced the timing chain and installed the correct intake manifold. I'm using a WCFB that I've rebuilt and double checked before testing with the 2 barrel mentioned above. I installed the distributor with #1 facing forward. The engine timing is correct and the compression is 125 on every cylinder. The engine has about 80,000 miles on it.