383 LT1 Vacuum issue
#2
Re: 383 LT1 Vacuum issue
Pull a vacuum line to check vacuum. The PCV sticks into the side of the intake manifold, but it connects through a passage to the lifter valley, not to the plenum. You won't see any vacuum at the grommet. You might see a vacuum at the end of the PCV valve, since it is hooked to the vacuum port on the intake manifold right below the throttle body. But the PCV valve is spring loaded to limit vacuum to certain operating conditions.
http://shbox.com/1/pcv_pipe.jpg
http://shbox.com/1/pcv_pipe.jpg
#3
Re: 383 LT1 Vacuum issue
OK I have vacuum. One other question. The pcv line which way does it flow? from the bottom front of the intake to the pcv? And the passenger valve cover tube breathes from the throttle body to the valve cover correct?
#4
Re: 383 LT1 Vacuum issue
Air from in front of the throttle body flows through a passage into the chamber under the throttle body rectangular cover. It flow into the hose, and into the passenger side valve cover. The air is pulled by vacuum through the crankcase and the lifter valley, into the sheet metal pan on the bottom of the intake manifold, and through a chamber on the driver's side of the intake manifold that the PCV valve sticks into. Vacuum from the intake manifold starts at the port under the throttle body, and pulls the air/crankcase vapor through the PCV valve, through the tube to the front of the intake manifold, and into the intake manifold at the vacuum port.
The vacuum source for 95-97 is different than 93/94. As noted in Shoebox's photo, 93/94 uses a vacuum port on the driver's side of the intake manifold, a couple inches behind the PCV valve/grommet, conneted by a U-shaped rubber hose.
The vacuum source for 95-97 is different than 93/94. As noted in Shoebox's photo, 93/94 uses a vacuum port on the driver's side of the intake manifold, a couple inches behind the PCV valve/grommet, conneted by a U-shaped rubber hose.
Last edited by Injuneer; 08-11-2012 at 09:51 PM.
#8
#10
Re: 383 LT1 Vacuum issue
#11
Re: 383 LT1 Vacuum issue
I for one have seen a bunch of people willing to help other people that either dont have the knowledge or experience repair their problems or guide them to proven choices. For me thats a very positive thing as most things are based from a desire to help rather than make money or promote a product. Sure there may be egos and opinions but thats better than learning the hard way or spending extra time and money on things. I am greatful for sites like this as ive took on a major project and the added confidence of having people who know what and were things are and wgat works and what dont. People like shoebox who took.the time to make a site with all kinds of needed info and pictures. In my book that is an awesome thing so keep helping others and the site will always be a good thing
#12
#13
Re: 383 LT1 Vacuum issue
I don't know if it's a good thing or a bad thing, but if you own a car for 17 years and work on modifying it for over 12 years, and spend about that much time on the same car forums, you're bound to learn something about it
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