Are these air injection pipes?

[dhenderz]

Starting to lay the new brake & fuel lines into the restored chassis. I took a ton of pics during the teardown process. Saw the pipes in the red circles and I cannot recall what these were for. I don't remember disconnecting them, but that was a while ago and i had some help along the way. I am thinking these were for the original air injector (emission) system. One routes across the front of the frame along the front cross member. The other appears to route rearward inside the frame rail, but I don't seem to have a pic showing where it stopped. It is possible that it just goes a few inches back along the driver side frame rail. Can't really tell from the pics I have. The original engine was a 400. Any ideas?

Thanks.

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[PrairieDrifter]

The one that snakes down into the frame rail and straight back to the engine crossmember and the ends there, is a breather hose for your front axle breather. It needs rubber hose from the nipple on the axle then it meets a metal line on the engine crossmember then on the other end of the metal line you need some more rubber hose and an axle breather check valve at the end.

The first one I’m not positive on, but I would be willing to bet if you had injection tubes on the manifolds it would most likely be apart of the emissions system. Someone else here can tell you for sure.

 

[Westislander]

Vapor recovery can?

 

[Blue Ox]

I'm going with front differential vent and evap cannister.

 

[bucket]

I'm going with front differential vent and evap cannister.

Yep, me too.

 

[dhenderz]

I can't tell if the original 400 had an air injector because that engine is long since gone. It was replaced at some point in the trucks history by another SB Chevy.

Does anyone have a picture (or can you take a picture) of this area of your truck?

 

[bucket]

The air injection systems that GM used didn't employ any frame-mounted hard lines.

The evap canister was only on the light GVW trucks. My '77 K5 has the higher GVW option and only has a tank vent that's mounted to the sending unit.