In addition I am trying a float which expels air but closes with water. I expect it to only bubble some each time I start the car. It goes through a check valve into the over flow; not the expansion tank.
I will probably try this sort of setup, up front.
One of my clients we laser cut for is a nationally known seller of custom radiators. I had a conversation with him last week on this set up. Who knows if it is a good set up until I try it but he had some very good info.
People around the country....on front engine cars...which is a simpler set up then ours, are doing custom setups where they eliminate the radiator cap. You are seeing a lot of custom cars with fill spots in the their tubing instead of in the radiator itself.
Many of these people are getting overheat issues. There is one solution which they are doing which is fixing ALL their problems. They are ADDING swirl tanks.
The problem is the air hangs in the coolant and cannot really separate as well in a small tube. A radiator tends to act like a swirl tank so that helps most cars other then a Pantera. If you are not using the radiator to vent, and if you still have problems they have been solving them with swirl tanks.
I did not set mine up that way but I can't help but think that the Pantera is a more complex system simply by the distance the radiator is from the engine and by the fact it is a little lower.
For me I am going to try it without a swill tank. If I have problems I will leave room to convert the coolant tube to a swirl tank at its present location.
This is the air vent with float. It is in a cap which is also an alternate fill location.:
