427 Tri-Power vacuum ? (Full Version)

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427 Tri-Power vacuum ?

  

tripowerrookie -> 427 Tri-Power vacuum ? (9/10/2008 3:54:37 PM)

What kind of vacuum psi should I be seeing out ot the manifold? If I test vacuum off the nipple back next to teh Distributor. If I''m not getting much at idle, what are the most likely culprits?

Thanks for any help.

  
73shark -> RE: 427 Tri-Power vacuum ? (9/10/2008 6:37:10 PM)

Welcome to the Corvette Forum.

You are probably getting a ported vacuum which is very low at idle due to it being sourced above the throttle page.  You need to get a direct source at the manifold.  Depending on your cam, it can range from ~10 to ~18 inches.

tripowerrookie -> RE: 427 Tri-Power vacuum ? (9/10/2008 9:44:13 PM)

I''m getting -2psi at idle.-10 at around 2k rpm''s. Gotta chase down a leak I guess.

tripowerrookie -> RE: 427 Tri-Power vacuum ? (9/11/2008 10:34:43 AM)

Here are a couple images of the situation

[image]http://i10.photobucket.com/albums/a133/srt4geezer/684273x2vacuumwide.jpg[/image]

[image]http://i10.photobucket.com/albums/a133/srt4geezer/684273x2vacuum.jpg[/image]

73shark -> RE: 427 Tri-Power vacuum ? (9/11/2008 5:41:08 PM)

Are you sure you''re getting direct vacuum from the intake manifold?  Not sure the engine would run w/ only 2 inches of vacuum.  I know the end carbs start to open as the vacuum decreases so they might be a source of manifold vacuum.  If you truly have only 2" at idle, then the end carbs would be almost wide open.

  

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