vacuum required to run power brakes and ac and rs doors on a 68

[jonboy1216]

how much vacuum does it take to run air conditioning,rs headlight doors,and power front disc brakes with four piston calipers?

[JohnZ]

Most Z/28's only pull 9"-11" Hg. of vacuum at a 900 rpm idle, and all had power disc brakes; not ideal, but all were built that way. Hydraulic-lifter engines typically pulled 15"-18" Hg.

[Mark]

You have vacuum cans for each of those systems so it really doesn't matter how much vacuum you run, the booster, a/c canister, and the RS canister will all trap the highest vacuum they see, such as under deceleration and hold it as long as your systems are tight.  I can close my RS headlights 30 seconds after i shut the engine off, and my brake booster will still have vacuum in it days later.

[jonboy1216]

thanks guys for the info          so if i have at least 9-11 hg with a new cam im good for a weekend cruiser right?

[JohnZ]

thanks guys for the info          so if i have at least 9-11 hg with a new cam im good for a weekend cruiser right?

Yup - all Z/28's were like that.