Help needed - vacuum leak, need retorquing intake manifold on 80's V-8
 

I have reason to believe my new intake manifold gaskets are leaking vacuum. I torqued them to 20 ft/lbs, and am seeing seepage around #3 cylinder.

What is the correct spec, I read it is 18-22 ft/lbs. Should I set to 22 or something else?

Also what is the correct sequence? I started with the center bolts and did it outward. I suspect when I removed 1 or 2 of the bolts in that area of the leakage that it did not "reseal" after the initial 20 ft/lbs then bolt removal, then back at 20 ft/lbs.

Any suggestions? Thanks!