I just bought a 1979 911sc. It has a surging idle. When it is reved up it runs great, but when the idle dips down it start poping through the pop off valve. I replaced the plugs, wires, rotor, cap and fuel filter with no luck. I decided to look for vaccume leaks.
I found this (Thermo valve see first pic) The vac diagram shows that the extra port should have a line going to the control pressure regulator. I think I found the CPR, but it has a vac line that runs to a "T" and spits off into another "T". I cant find any vac lines that would have gone to the open port on the Thermo valve. Does anyone have any pics of their vac line set-up? Mine is different to how the diagram is showing.
