Engine vacume and braking
Race Director
Joined: Dec 2006
Posts: 10,383
Likes: 4
I found this site a while back and thought it was a good read with a neat interactive bit at the bottom of the page too.
http://www.secondchancegarage.com/public/186.cfm
http://www.secondchancegarage.com/public/186.cfm
Melting Slicks
Joined: Dec 2009
Posts: 2,232
Likes: 284
Is that a ported source of vacuum you are reading? The vacuum should be strongest at idle, try hooking it to the manifold near where the boosters connects & see what it reads. You can try advancing the ign. timing, & you can also advance the cam timing too, both may increase manifold vacuum alittle.
Melting Slicks
Joined: Dec 2009
Posts: 2,232
Likes: 284
Your psi reading are of no use in vacuum, b/c vacuum is measured in inches of mercury,HG, anyways you should have 16.5HG. or up at idle(you won't have much assist w/ the throttle open, so those rpm readings don't matter), but most will be near 20HG, stock cams. The more you open the throttle the vacuum gauge should move torwards zero.
With the psi readings you gave us, I can't tell you if you need more vacuum, take a picture of the gauge while the car is at idle.
With the psi readings you gave us, I can't tell you if you need more vacuum, take a picture of the gauge while the car is at idle.
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