Vacuum lines turbo 400, l6 250, one barrel?

[DanMcG]

I just redid the valve cover gasket and found the vac line off the transmission just laying by the carb. ant help with where to plug it into would be appreciated. I can't find a home for it? Line is the smaller one on the left in the pic.
Also what's the large port to the right for?
Thanks, Dan

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[bucket]

That fitting in the hose fell out of the carb somewhere. It will go to a constant vacuum port.

I don't know about the unused nipple.

 

[DanMcG]

Is the base of the carb constant vacuum? there is a port that has a rubber cap over or do I need to go to the manifold?
Can I put a tee in the brake booster vac line, and where would I find the tee? Thanks for the response Bucket.

I should add that this was a manual tranns truck in the beginning then someone added the 400. the vac line may have never been hooked up.

 

[1987 GMC Jimmy]

Ports below the throttle shaft are ported vacuum, and the ones above are manifold. If you have a gauge, you can discern ported sources by a needle that jumps when you move the throttle and stays up as long as you’re on the throttle. That top port might go to the THERMAC and/or advance canister. I’d be more certain of it any other day, but I caught the freshman flu, and it feels like someone hit my brain with a spatula.

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[bucket]

I believe you said that backwards. Manifold vacuum would be below the throttle shaft.

That nipple in the hose is for a carb, they tend to fall out of a quadrajet. Since that's been swapped in, maybe they just used that nipple as a connector and it doesn't actually belong in your carb. As long as it gets hooked to constant manifold vacuum, that's really all that matters.

 

[DanMcG]

Thanks for the help guys, I'll get a gauge and try to learn something new.

 

[1987 GMC Jimmy]

I believe you said that backwards. Manifold vacuum would be below the throttle shaft.

That nipple in the hose is for a carb, they tend to fall out of a quadrajet. Since that's been swapped in, maybe they just used that nipple as a connector and it doesn't actually belong in your carb. As long as it gets hooked to constant manifold vacuum, that's really all that matters.

Yeah, you’re absolutely right. And I know that, too. I think I’m going to lie down for a bit before I tell someone to put a plugged in toaster in the bathtub.

 

[DanMcG]

Thanks again guy's. Just to wrap this thread for other who might be looking. I found this capped port at the bottom of the carb next to the valve cover. I connected it but haven't text driven it yet but it should be fine.

Port is circled in red

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