Vacuum leak under carb

[MannyL]

I’ve now sanded the shit out of everything on glass used all different gasket types and sealant finally took it to a shop that was able to get it to seal but now a week later it won’t idle unless on the fast idle cam and even then it’s at 1000rpm and pulsing. Is there any magic permanent fix so I can drift it without having to worry about the vacuum load breaking my gasket seal. It’s a 1980 720 with a Z22 and 32/36 Weber one piece adapter with inset Allen heads 

[datzenmike]

Check the EGR valve. They can become coated with exhaust deposits and this will prevent them closing and sealing. At idle there isn't (or shouldn't be) any EGR as the dilution of the idle mixture with inert exhaust gasses will cause it to not run.  The EGR can be disconnected and removed and wire brushed clean.

 

Look in front of the carburetor on the intake for a fitting used as a vacuum source for the ATC on the air filter snorkel, the AB valve and the charcoal canister. Close every hose off and see if the idle improves. If so, find out if a hose is cracked or split and leaking vacuum. 

[Fat510]

7 hours ago, MannyL said:

 so I can drift it 

 

Here's the root of the problem

[datzenmike]

I saw that but it didn't register. Drifting is just another way of saying beyond abuse. This will cause things to break or act up that normally would never do so.

 

32/36 Weber. Another cause. Take the adapter off and replace the gaskets. Use a thread locker/sealer on the adapter screw threads because they are notorious for working loose. Paying a mechanic to do this simple stuff is like paying him to breathe for you.

 

There is a fitting on the intake with 3 or 4 hoses going to it to send intake vacuum to several things. Cap them all and see if the idle improves and if it does find out which one has the leak.