vacum leak in edel carb

i have a 1406 600cfm carb on my 350. it was running perfectly.i cranked it up one morning, pulling out onto the main road ,i gave it some gas and it poped through the carb. i got to the red light and noticed it wasnt running right.pulled over and found that i had a vacum leak. went home ,and checked around the intake and carb with starting fluid and found it to be around the carb. changed out the base gasket and still had the same problem.i took the 600 off and put a 750 that i had on it and it runs like it should.i took the 600 apart but could find nothing wrong the gaskets didnt have any signs of leakage. has anyone had this problem? is there anything inside that might have gone bad?

Check the gasket surfaces for flatness. Backfire could have warped something. A piece of fine emery on a glass surface will work to grind them flat again.
Check your base gasket against the carb base, some have very little leeway around the edges and don't take very much to make them leak. Find one that gives the best coverage with your carb.

i checked the surface with a level and apeered to be right. tried another new gasket and got the same results. i noticed that it did idle up more when i sprayed around the front in the area of the mixture screws,but i couldnt tell if it was them or the factory plugs.

When I first started working on cars, The gent that was mentoring me warned me about a "Ghost Leak" when checking for vac leaks at the front of a carb with spray chemicals. The vapor was making it into the air that the carb was sucking in, and causing the idle to go up, imitating a vac leak that wasn't there. We took a legal pad and tore off the cardboard back. Rolled it up and made a tube to go onto the air horn of the carb ( a make shift stack ). Then we used a pump spray bottle with water and did not get the result.

In my particular situation, it turned out to be the power brake booster sucking air. Hope you find your problem...