Author Topic: vacuum required to run power brakes and ac and rs doors on a 68  (Read 3881 times)

jonboy1216

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

JohnZ

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Re: vacuum required to run power brakes and ac and rs doors on a 68
« Reply #1 on: August 04, 2009, 02:25:42 PM »
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.
'69 Z/28
Fathom Green
CRG

Mark

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Re: vacuum required to run power brakes and ac and rs doors on a 68
« Reply #2 on: August 04, 2009, 04:06:45 PM »
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.
Mark C.
1969 Indy Pace Car
350/300HP RPO Z11

jonboy1216

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Re: vacuum required to run power brakes and ac and rs doors on a 68
« Reply #3 on: August 05, 2009, 03:19:35 AM »
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

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Re: vacuum required to run power brakes and ac and rs doors on a 68
« Reply #4 on: August 05, 2009, 03:45:29 PM »
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.
'69 Z/28
Fathom Green
CRG