I have searched through, and can't exactly find what I need. I am trying to find a vacuum diagram for a 1977 F-100 49 state truck with a 351M and C6. The truck is catalytic converter equipt, air pump, evaporative system and EGR. My experiance with 1977 was an F-150 originally with a 300 later a 390 4V camper special engine. Thanks for any help.
Some old setups did put a delay valve inline with the EGR vacuum. This was an effort to combat driveability issues with smog motors back in the late 70s.
The air cleaner vacuum routing is a separate system and unfortunately I did not put it in my drawing for clarity. The air cleaner vacuum routing is for the hot-air intake system; it is used to draw in warm underhood air during warmup instead of cold outside air to prevent the carburetor from icing up. All it is, is a line from manifold vacuum (can grab it from the vacuum tree) to a bimetallic switch in the air cleaner. Another line goes from the same switch to the vacuum diaphragm on the snorkel of the air cleaner. Some setups included an inline check valve as well, to keep the air door in the snorkel from opening back up during periods of low vacuum.
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