The flapper door inside the air cleaner snorkel is controlled by a thermostat that opens it up as the engine heats up but what is the vacuum override for? If the engine is still cold and you give it full throttle will it open the door? I have a 68 with a 302 4v (J code).
The vacuum over ride was used on early 302’s in 1968. Like you say, it will open the flap on full throttle acceleration. It was eliminated around January 1,1968.
Yes, mine is an early 68. Build date was January 23. They were probably using up the stock of this kind of air cleaner before switching to the new one.
Yours should have had the later style. January 1968 is 5 months into the model year like it is today.
Mine definitely has the vacuum over ride so I’m not sure why it doesn’t have the later one.
I have a '68 F code built 2/9/1968 and it has the vacuum cylinder on the snorkel too. I know the history of this car, I bought it from the original owner. and have owned it since 1980 so think your timeline may be wrong.
Reminds me of the '67 XR-7 that has was mothballed and had 2 miles on it. CCOA got to see it about 20 years ago, car is as close to a time capsule as one can get. Remember the big deal was that the upper radiator hose had one worm clamp and one tower type. By the build date that would be wrong and I’m sure in a concourse judging I’d bet they would delete points for it being wrong, but it is how it came from the factory.