I have a "home made smoke machine" that I would like to use to check for manifold vacuum leaks.

My question - where on the manifold to I connect the hose to check for leaks? If I connect it to the vacuum port on the back of the manifold and plug the part where the brake booster and transmission vacuum connect, smoke will come out thru the top of the carburetor.

If I connect it to the middle port on the front of the carb, it blows freely thru the top of the carburetor.

So, how the hell do I check the manifold for leaks? I feel so dumb asking this, but I am clearly missing something.

I have tried soapy water, carb cleaner and propane and cannot find anything.

This is not my first post - I actually had trouble with my previous account - "myfreeford" and had to create a new one. So, how the hell do I check the manifold for leaks? I feel so dumb asking this, but I am clearly missing something.

Any help with this would be great.