here is the readings for a 1987 carbed subaru
250 rpm (not 2500.. this is really 250, and even less)
this is maximum, 22 in Hg of vacuum. I first saw this in the 80s.. waddya know, it is still there. Super Stoich... gotta love the real thing
and on another note, one to learn safe max psi for boost for an old sube, can learn it from converting inches of mercury to psi (psi because I am american)
22*.4912=10.8064 psi
In the little sube world I am in, this was a safe rule of thumb I never got to. (never ran a turbo)
and 10.8 psi is .744 bar
interesting.
of course today and boost and max is like a crack addiction to many, but above is the rule I would follow...I never learned if that worked, but it sounded smart enough. Simply to stay safe within oem mechanical setups.