Reply to "Radiator Cap"

Jerry, there are TWO potential problems with using a U.S radiator cap on the stock surge tank.
The first is, U.S caps are slightly shorter than the Euro cap the tank was designed for. So a 16 lb cap may only hold 6 or 7 lbs of pressure. You can confirm this by testing.

The second problem is, the solder job done to connect the tank neck to the tank body is often poor-to-abysmal. There may be grooves and bumps on the bottom part where the cap rubber is supposed to 'seal'. Thus a new cap may seal decently to start with, but as time goes on the rubber ages harder and leakage starts. What's worse, the leakage runs down the tank, down the inner fender and into that big oval hole in the right lower frame rail. Where it sits rusting away your structure unless the aux. drain holes have been drilled in those rails. Note that not all Panteras have both problems, but many do and it takes a precision depth micrometer to tell the neck height difference.

The simplest fix for BOTH problems is to take the tank to ANY radiator shop in the country and have them unsolder the Euro neck and replace it with a std. U.S made brass neck. Once this cheap job is done and the solder quality is visually inspected, any U.S radiator cap will work. Lots of cars have had this done since the cars were still being built new in the '70s. The neck replacement is not apparent even to a trained eye, if you are into keeping your Pantera 'stock'.
Or you can sometimes find rad caps for BMWs or Ferraris etc that were made in Europe and will fit an unaltered tank better- for many many $$$. And they do not fix a bad solder-job.