The rings help for alignment when installing the manifold

I guess in that way the can help in preventing leaks,
they can also cause a leak if cocked a little when installed,

or as I found out in a step ring I used
was made to thick and caused a leak


Best method I found to stop a leak was to take my manifold to a machinist to deck it, then torque the assembly in sequence using the torque specs in the manual. Torquing the manifold and heat box in steps.