My 1968 V8 FB had the thermactor system originally installed. When I inherited the car, one of the check valves was missing so I removed the entire system. Now I'm ready to reinstall - I still have all original components, including all of the hoses (which were in really good shape), pump, cannister and smog tubes that screw into both sides of the engine block. So I'd like to get check valves to screw onto the tubes that are as close to original as possible.
The blue valve on the left was on the car and was metal gray when I got it - I painted it blue since then. The middle one I found on eBay and the one on the right is from NPD. What is noteworthy is that the mechanism inside each of the two repro valves is different. The eBay one has a spring holding what appears to be a simple plate in place - I'm assuming it moves and opens the valve only where there is enough fresh air pressure coming from the smog pump. However, the NPD version has no spring and the plate inside doesn't move - it is simply held in place with a screw and has holes in it. This appears to be similar to the blue one, but the blue doesn't have any Fomoco marking so I'm not even sure it's original.
Can anyone shed any light as to which of these check valves (if any) would pass muster? Do the two repro check valves work in the same way? Or is one or both of them simply incorrect for my car?
