Vacuum Pressure
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Senior User
Joined: Apr 2003
Posts: 327
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From: Chalmette, LA
Vacuum Pressure
I have an 1984 302 with a 4 barrel Holley 600cfm. My vacuum pressure is registering at 20 psi.
What is the normal standard and and it is hard to achieve more vacuum pressure out of my 302?
I appreciate any information provided because I just put this 302 in my truck and I am putting the finishing touches on it and this is a question that I cannot seem to find the answer to.
Thanks.
What is the normal standard and and it is hard to achieve more vacuum pressure out of my 302?
I appreciate any information provided because I just put this 302 in my truck and I am putting the finishing touches on it and this is a question that I cannot seem to find the answer to.
Thanks.
Posting Guru
Joined: Jul 2002
Posts: 1,147
Likes: 1
From: East Coast
Vacuum Pressure
If it's hanging steady at 20 inches of vacuum than that's good. It shouldn't bounce around too much. Between 18-20 is about right. Adjusting the timing can change your idle vacuum reading. Advanced timing will give a higher vacuum reading. If you hit the throttle from idle quickly and let off the vacuum should drop to around 5 and jump back up again.
Post Fiend
Joined: Nov 2002
Posts: 9,987
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From: Memphis, TN
Thread Starter
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Senior User
Joined: Apr 2003
Posts: 327
Likes: 0
From: Chalmette, LA
Vacuum Pressure
Thank you so much for all your information. It was all very helpful and the diagrams are great and anyone can understand them. Thank a lot and I will take all those tips into consideration.
