Vacuum pressure
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architect
- Posts: 321
- Joined: Thu Jul 21, 2016 9:48 am
- Your car is a: 1978 Fiat Spider
- Location: Austin, Texas
Vacuum pressure
I recent purchased a vacuum gauge.. on my 78’ de-smogged.. I’m getting zero vacuum at idle and about 5 hg at mid rpm.. what numbers are we supposed to look for?
78 Fiat 124
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SteinOnkel
- Posts: 1000
- Joined: Tue Feb 19, 2019 9:31 pm
- Your car is a: 1978 124 Spider 1800
Re: Vacuum pressure
17-23 inch mercury on a healthy engine @ idle. Depends on speed, compression ratio etc.
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Nut124
- Posts: 748
- Joined: Wed Oct 25, 2017 6:39 pm
- Your car is a: 1978 124 Spider 1800
Re: Vacuum pressure
Where are you measuring this? The manifold vacuum is normally connected to the brake booster.
Your numbers seem to work backwards. Vacuum is supposed to be greatest at idle and drops as the throttle is opened.
Sounds more like some vac port above the throttle plates.
Your numbers seem to work backwards. Vacuum is supposed to be greatest at idle and drops as the throttle is opened.
Sounds more like some vac port above the throttle plates.