What do you mean by "new"? Fresh rebuild, or new to you?
An unlit propane torch works better for finding vacuum leaks. Try that before you do anything else.
Where do have the timing set? You need to have the needle on the "BB" everytime the #1 cylinder fires.
It would be cool if you had someone nearby who had a known good-to-go carburetor to try if you don't find a vacuum leak, and your timing proves to be correct.
