I installed a new Holley 600 carburetor on my Pantera about two years ago and recently I noticed that a very small amount of fuel was weeping out of the accelerator pump housing that is located under the front float bowl. In my case, I noticed the leak while it was in the weeping stage not the full leaking stage that could cause a potential fire problem when the fuel drips on the hot intake manifold. I tried tightening the housing screws but the leak was in the pump diaphragm.
The fuel collects directly bellow the front corner of the carburetor in the recess in the intake manifold. The fuel residue on the intake looks like oil because of the small amount of fuel that weeps out of the carburetor.
Apparently the diaphragms used by Holley for the accelerator pump can start leaking when they are not very old. I was able to find a new Holley diaphragm at Advance Auto for about $3 and it was an easy repair.
The side view of the pump housing
The bottom view of the pump housing
The pump housing cover removed with the diaphragm visible
View of the diaphragm removed with the spring still in the housing
View of the diaphragm and spring removed
If you have a Holley 600 carb on your car you might want to check diaphragm for leaks as part of your regular ongoing maintenance checks.