The car...

87 Formula, 350, Edelbrock Performer EPS Intake Manifold, Edelbrock Performer 600 Carburetor, 700R4 Transmission. The car is a rebuild with a new BluePrint crate engine. The original engine was a computer controlled carbureted 305 LG4 engine.

The part in question...

Look at the pictures below. Between the carburetor and the distributor there is a part screwed into the manifold, it is a vacuum port. I don't recall if it was hooked up to anything or not. I have always had a vacuum sound coming from the engine, this may have been it. Anyway if I put my thumb over the hole to close it up the engine idle goes low and rough.





Question...

What is this thing? What is supposed to be hooked up to it? The rest of the engine is together and ready to go.

 

Yup. That's a massive vacuum leak. Looks like it's time to cap it, then retune the carb. My guess is that it was intended for a PCV valve or power brake booster.

 

you do have a way with words vader. i am still laughing at that one.

 

Currently the brake booster vacuum is going to the rear of the carb through that metal pipe. Does it make any difference where it's hooked up to? The carb or the intake?

 

It goes to the box above the brake booster. I think I deleted the picture I have of it so I can't repost, it's in this thread https://www.thirdgen.org/forums/carb...hind-carb.html

That brake booster should go to that metal tube and the back of the carb, you have it correct.

 

Thanks for the replies. I plugged it. Worked great.

 

That vacuum port normally is connected to a hard line with a short piece of rubber hose to hold it in place. The hard line goes down the back of the engine to the vacuum modulator on the transmission.

If you don't have a modulator or have a manual transmission, just plug it.