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Old 03-02-2020, 05:14 PM
allenga allenga is offline
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Default Photo's of a 77 W72 Vacuum Lines

Hey Guys, I am looking at photo's of original cars and the factory service manual and am seeing differences in the routing of some vacuum lines. Does anyone have a picture of where the two stock air clearer vacuum lines plug into.

Also, on the front of the carb, there is a check valve with vacuum line that I had plugged into the front of the quadrajet but the manual says, it should be to manifold vacuum. Thanks!

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Old 03-02-2020, 11:16 PM
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On a '77 Z code 400 with auto and manual trans low altitude there are 4 vacuum lines that go to the air cleaner from the engine......

Two to the air cleaner TVS for the secondary vacuum break...red stripe from the "tree" on the back of the carb base to the inside port, white stripe from the secondary vacuum break to the outside port.

One single hose from the intake manifold vacuum source directly under the air cleaner in front of and below the carb for the air temp sensor attached to the underside of the air cleaner. Part of the thermac system.

The other vacuum line is a very weak vacuum signal for the thermostatic choke. From the choke stove pipe to the fresh air modulator mounted on the underside of the air cleaner.

The EFE check valve gets it's vacuum signal from a manifold vacuum source on the front of the carb for both auto and manual trans.

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Old 03-02-2020, 11:22 PM
allenga allenga is offline
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Quote:
Originally Posted by abefromen View Post
On a '77 Z code 400 with auto and manual trans low altitude there are 4 vacuum lines that go to the air cleaner from the engine......

Two to the air cleaner TVS for the secondary vacuum break...red stripe from the "tree" on the back of the carb base to the inside port, white stripe from the secondary vacuum break to the outside port.

One single hose from the intake manifold vacuum source directly under the air cleaner in front of and below the carb for the air temp sensor attached to the underside of the air cleaner. Part of the thermac system.

The other vacuum line is a very weak vacuum signal for the thermostatic choke. From the choke stove pipe to the fresh air modulator mounted on the underside of the air cleaner.

The EFE check valve gets it's vacuum signal from a manifold vacuum source on the front of the carb for both auto and manual trans.
Thanks. My air cleaner only has two lines going to car. ?
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Old 03-02-2020, 11:30 PM
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abefromen abefromen is offline
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You're missing the rest of the hose from the fresh air modulator to the choke stove pipe.

Do you have the two port TVS? Its mounted in the side of the air cleaner.
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Old 03-02-2020, 11:38 PM
allenga allenga is offline
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Quote:
Originally Posted by abefromen View Post
You're missing the rest of the hose from the fresh air modulator to the choke stove pipe.

Do you have the two port TVS? Its mounted in the side of the air cleaner.
I do have that. I left it connected to the car.

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Old 03-02-2020, 11:43 PM
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Here is my Can Am air cleaner from the W72 in it.

The sensor positioning is a little different in yours. Maybe it's an A body vs. F body thing, idk.
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Old 03-05-2020, 12:38 AM
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Allenga, I have my hoses still connected the factory way. I am having a kidney stone surgery tomorrow. I will be out of commission for a week or so. If you still have any need in this area, let me know...

Where do you stand on your paint job and engine mods?

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Old 03-05-2020, 12:59 AM
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http://enthusiastnetwork.s3.amazonaw...ound%7C875:492

http://enthusiastnetwork.s3.amazonaw...ound%7C875:492

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Old 03-20-2020, 06:02 PM
allenga allenga is offline
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Quote:
Originally Posted by 77 TRASHCAN View Post
Allenga, I have my hoses still connected the factory way. I am having a kidney stone surgery tomorrow. I will be out of commission for a week or so. If you still have any need in this area, let me know...

Where do you stand on your paint job and engine mods?
The car in this photo has that little vacuum line with the check valve connected to the carb. The diagram in the 77 shop manual has this line going to the intake manifold.

Which is correct.
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Old 03-20-2020, 09:15 PM
Aus78Formula Aus78Formula is offline
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Might be different versions, the diagram of the same car has it going to carb base.

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Old 03-20-2020, 10:59 PM
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They just mean manifold vs. ported vacuum on the carb. (lower, on baseplate, is manifold). Here is a '76 diagram which should be close to the '77.
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Old 04-17-2020, 05:03 PM
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I have the colored vac line schematic also.

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Old 04-18-2020, 11:20 PM
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Quote:
Originally Posted by allenga View Post
The car in this photo has that little vacuum line with the check valve connected to the carb. The diagram in the 77 shop manual has this line going to the intake manifold.

Which is correct.

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Old 04-18-2020, 11:23 PM
Aus78Formula Aus78Formula is offline
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As above, it doesn't go to manifold itself, but a manifold port from carb, manifold vacuum vs ported vacuum.

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