Vacuum diagram needed
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Joined: Aug 2001
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Vacuum diagram needed
I am needing to smog my truck in the next couple weeks. Truck has not been smogged/registered for more than 10 years, so could be interesting. Anyway, I am in need of vacuum diagram and any air cleaner pictures that someone might have of for similar truck. My air cleaner is long gone and I have a few alternatives but none seem to match. AutoZone does not have what I need...
1977 F250 4x4 w/ 351m
Manual Trans, no AC
Non-Catalyst, 8100 GVWR
Produced in San Jose, CA
The tag on the valve cover is mostly gone, in trying to make it our I think it says
C 71
R 0
S 12
Like I said it is pretty faded/stained and I can really make it out clearly so open to interpretation. Any help would be appreciated.
Farmengineer
1977 F250 4x4 w/ 351m
Manual Trans, no AC
Non-Catalyst, 8100 GVWR
Produced in San Jose, CA
The tag on the valve cover is mostly gone, in trying to make it our I think it says
C 71
R 0
S 12
Like I said it is pretty faded/stained and I can really make it out clearly so open to interpretation. Any help would be appreciated.
Farmengineer
MSEE
Joined: Apr 2004
Posts: 10,386
Likes: 35
From: Austin, TX
Here's a general diagram you can use. One thing it doesn't show is the hot-air intake system, which uses manifold vacuum. If you end up running a stock air cleaner, let me know and I can tell you how to route that. Let me know if you have any other questions.
Postmaster
Joined: Jul 2001
Posts: 4,956
Likes: 10
From: MD
Air cleaner assembly...
VACUUM:
On the lid itself, there are two vacuum ports. One port is routed from the manifold vacuum tree. The other one goes to the vacuum motor that operate the flap. In between the vacuum motor and the port on the lid, there needs to be a delay valve installed. On the housing just north of the vacuum motor duct, there are two ports. This is a part of the emissions system. Your application may or may not have this.
The passenger side valve cover has an opening for the PCV system. This needs the crankcase breather filter installed. It filters fresh air into the engine via the passenger side valve cover.
VACUUM:
On the lid itself, there are two vacuum ports. One port is routed from the manifold vacuum tree. The other one goes to the vacuum motor that operate the flap. In between the vacuum motor and the port on the lid, there needs to be a delay valve installed. On the housing just north of the vacuum motor duct, there are two ports. This is a part of the emissions system. Your application may or may not have this.
The passenger side valve cover has an opening for the PCV system. This needs the crankcase breather filter installed. It filters fresh air into the engine via the passenger side valve cover.
