Could anyone tell me the purpose of the screw on the carb manifold, am in the process of renovating a 1992 Diversion and have cleaned them, touched them up with some high temp paint and now replacing the screws and washers.

The screws were in tight and one needed an impact driver to get a couple of them to turn, but cannot see any residue of thread lock. Could anyone tell me if these require thread locking, or if there is a torque setting for these?
Thanks in advance for the help
Jason