Yes, that meters it as throttle is opened, but then check valves hold or meter vacuum after that. Do you have the white vac valve on the top center of the valve cover?

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81 300CD (sold) 1972 280 SEL 4.5 (sold) 1966 250 S 4 spd (sold) 1974 450 SL (sold) 86 BMW 325ES (sold), 1973 280C (sold) 1988 300 SE.