72 Datsun 521weber conversion.

[Aqualung]

I recently upgraded to a Weber 32/36 and was wondering what do I do with the vacuum tee coming out of the manifold?  It seems to draw a good amount of vacuum ,  I tried capping it but instantly noticed an adverse effect on the idle speed. The only thing I have hooked to the carb are the vacuum advance from the distributor and the fuel line.

[datzenmike]

That should be sealed off if not used. The reason it acts badly when you seal it is because the carburetor is set or tuned to work with or account for this huge unnecessary vacuum leak. Seal it up and adjust the idle mixture and idle speed.

[d.p]

Cap it off. 

[Aqualung]

1 hour ago, datzenmike said:

That should be sealed off if not used. The reason it acts badly when you seal it is because the carburetor is set or tuned to work with or account for this huge unnecessary vacuum leak. Seal it up and adjust the idle mixture and idle speed.

I was pretty sure the only vacuum that gets used was the vacuum advance.  I haven’t made any adjustments to the carb yet but I will try and tinker with it.