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12-31-2013, 06:06 PM
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#1 |
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Registered User
Join Date: Dec 2013
Location: kailua hi
Posts: 8
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Unknown line
Trying to figure out what this line is. The guy that had the truck before had it run into a pcv valve that connects to the manifold but didn't have the valve connected to the carb. It runs to the back of my transmission. Can anyone help me out?
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12-31-2013, 06:09 PM
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#2 |
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Registered User
Join Date: Jun 2012
Location: Meeker, ok
Posts: 146
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Re: Unknown line
Its the vacuum modulator for the th350. It has to be hooked up for proper shifting. It should connect to the intake manifold.
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Trevor 74 C20...work in progress. 04 Saturn Ion...Daily Driver |
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12-31-2013, 09:24 PM
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#3 |
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Registered User
Join Date: Dec 2013
Location: kailua hi
Posts: 8
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Re: Unknown line
The valve that it connects to has two ports. I'm assuming that I should keep the second one plugged and not connected to the carb?
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12-31-2013, 09:53 PM
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#4 |
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Registered User
Join Date: Dec 2011
Location: Arlington WA
Posts: 1,728
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Re: Unknown line
thats the vacuum modulator valve on a th350. it helps control your shift points with your vacuum. shift earlier when just cruising of holds the gear long when wide open. if its not connected at all you will just shift off of the governer. if i recall correctly, i havent ran an automatic in a while
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GMC C15 355 SM465 3.73 80 C10 cruiser build thread 79 short stepside crew cab. big and ugly. build thread |
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12-31-2013, 11:09 PM
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#5 |
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Registered User
Join Date: Dec 2013
Location: Humble, Texas
Posts: 185
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Re: Unknown line
That modulator in the pic looks like it is leaking fluid probably needs to be replaced. Got a pick of the valve that it connects to? The reason I ask is that you said it has 2 ports and the modulator needs vacuum to work correctly. If that valve isn't connected to the carb/intake that second port needs a hose hooked to a vacuum source.
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I know the "VOICES" aren't real but they have some great ideas. 1978 GMC Sierra Classic C25 1983 Datsun 280ZX Turbo 1997 Chevy Cheyenne K2500 1999 Polaris Sport 400 |
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12-31-2013, 11:31 PM
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#6 |
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Registered User
Join Date: Dec 2013
Location: kailua hi
Posts: 8
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Re: Unknown line
Yea I have to go over my transmission with a fine tooth comb because it think there's more than one leak. So I do need to hook the other port up to the carb?
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12-31-2013, 11:42 PM
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#7 |
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Registered User
Join Date: Sep 2008
Location: spinawheel sc
Posts: 108
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Re: Unknown line
no thats hooked up right.straight vaccum off the monifold
Last edited by 875.3CHEVY; 12-31-2013 at 11:45 PM. Reason: clarification |
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01-01-2014, 12:09 AM
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#8 |
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Registered User
Join Date: Dec 2013
Location: kailua hi
Posts: 8
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Re: Unknown line
The pcv valve port being used is the one that goes to the transmission not the carb.
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01-01-2014, 12:23 AM
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#9 |
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Registered User
Join Date: Dec 2013
Location: Humble, Texas
Posts: 185
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Re: Unknown line
I agree with 875.3, it is connected correctly. To help prevent the vacuum hose from collapsing, the nipple on the pipe is supposed to fit directly into the fitting on the intake with a hose over the union.
__________________
I know the "VOICES" aren't real but they have some great ideas. 1978 GMC Sierra Classic C25 1983 Datsun 280ZX Turbo 1997 Chevy Cheyenne K2500 1999 Polaris Sport 400 |
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01-01-2014, 12:46 AM
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#10 |
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Registered User
Join Date: Sep 2008
Location: spinawheel sc
Posts: 108
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Re: Unknown line
the fitting behind the carb with the orange line and the capped off port is not a pvc port.it just straight vaccum.that what the trans needs.pvc should come off the carb and should be 3/8 in size.hope this helps
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01-01-2014, 01:38 AM
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#11 |
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Registered User
Join Date: Dec 2013
Location: kailua hi
Posts: 8
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Re: Unknown line
Thank you guys very much. I was very confused haha.
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