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#1
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68 400 vacuum routing
I removed vacuum to headlights and egr, added power brakes and trying to figure out these hose attachments, this is 4 speed car and trying to figure out small port on front of intake manifold, some say it T with line from valley pan to carb base
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Almost done 68 GTO 4 speed Rust Bucket}Step 18 engine accessories area http://forums.performanceyears.com/f...=1#post3561418 |
#2
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Here is a current picture
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Almost done 68 GTO 4 speed Rust Bucket}Step 18 engine accessories area http://forums.performanceyears.com/f...=1#post3561418 |
#3
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This port?
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Almost done 68 GTO 4 speed Rust Bucket}Step 18 engine accessories area http://forums.performanceyears.com/f...=1#post3561418 |
#4
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1. EGR? 68s didn't have an EGR.
2. The factory set up on all 68s used a 5 port thermo switch for vacuum control. It was modified to use three ports later in the model year. Your engine has a three port thermo switch from a later model engine. 68 manual transmission cars used a de-acceleration valve mounted to the passenger side intake manifold creating a jumble of vacuum hoses for distributor advance. It would take a few paragraphs to describe how it worked. If you are wanting to recreate the factory setup, this is how it's done. Modified version 3. If you just want to have manifold vacuum advance, plug all the other openings except for the one at the rear of the carb thats used for the power brakes. There is an additional manifold vacuum vacuum fitting on the right rear carburetor stud. 4. If you want to use Ported vacuum use the front drivers side port on the carb. 5. The intake manifold nipple at the front is used for the factory air cleaner to control the air snorkel valve.
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Ed 1968 GTO (Thanks Mom) 2006 Silverado 2007 Cadillac SRX 2015 Chevy Express 2024 Cadillac LYRIQ |
#5
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Ed 1968 GTO (Thanks Mom) 2006 Silverado 2007 Cadillac SRX 2015 Chevy Express 2024 Cadillac LYRIQ |
#6
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Thanks, that last picture is helpful, I got egr from trying to decipher from newer schematics
I may plug off the small manifold to air cleaner, looks like a special adapter needed for hose end. . My 3 port is aftermarket Are you suggesting ading a deceleration valve, I remember there used to be something on passenger side
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Almost done 68 GTO 4 speed Rust Bucket}Step 18 engine accessories area http://forums.performanceyears.com/f...=1#post3561418 |
#7
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You already have it (Vacuum valve at the rear with a black plastic cover). And unless you're doing a concours restoration you don't need it.
The only thing missing from your air cleaner snorkel are the vacuum lines from the snorkel valve to the temperature switch under the air cleaner to the manifold fitting.
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Ed 1968 GTO (Thanks Mom) 2006 Silverado 2007 Cadillac SRX 2015 Chevy Express 2024 Cadillac LYRIQ |
The Following User Says Thank You to OG68 For This Useful Post: | ||
#8
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.???
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The Following User Says Thank You to rwfisher For This Useful Post: | ||
#9
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What would you suggest for brake booster vacuum? I also have the large looks like manifold vacuum port on front of carburetor, is this plugged now?
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Almost done 68 GTO 4 speed Rust Bucket}Step 18 engine accessories area http://forums.performanceyears.com/f...=1#post3561418 |
#10
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You may have a base plate from a different year. That large port wasn't on 68 carbs. Power brakes use manifold vacuum from the rear baseplate opening. So move the PCV hose to the brass manifold fitting, and cap the opening.
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Ed 1968 GTO (Thanks Mom) 2006 Silverado 2007 Cadillac SRX 2015 Chevy Express 2024 Cadillac LYRIQ |
The Following User Says Thank You to OG68 For This Useful Post: | ||
#11
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I connected carburetor advance to distributor and brake booster from the back and plug everything else.
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Almost done 68 GTO 4 speed Rust Bucket}Step 18 engine accessories area http://forums.performanceyears.com/f...=1#post3561418 |
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