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#1 |
Registered User
Join Date: Apr 2013
Location: Princeton, NJ
Posts: 40
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Carburetor Vacuum Lines
Hi guys,
I have a 1971 C20 with a 350 and Quadrajet carb. Take a look at pictures of my carb: front view: http://imageshack.us/f/407/cdiv.jpg/ diagonal side view: http://imageshack.us/f/545/3d7u.jpg/ I have two concerns: 1. In the front of the carb, what is that vacuum port for? What is it supposed to be connected to? If I put my finger on it, I feel a pretty good suction. I feel like it's missing a hose to somewhere. 2. In that diagonal side view image, is that hose supposed to be routed back up to the air cleaner? When I got the truck it was only connected on the carb end so I guessed that the other end goes up to the cleaner, but I'm not sure. Is it the hose that keeps the float bowl fuel pressure constant? It'll be great if someone could point out what those two vacuum ports are for. Thanks in advance, David Last edited by dzwestwindsor; 08-07-2013 at 11:48 PM. |
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#2 |
Registered User
Join Date: Jun 2013
Location: Saint Louis, MO
Posts: 142
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Re: Carburetor Vacuum Lines
Pcv on the valve cover?
Actually on my truck ive got 3 spots in the front for hoses...vac advance, fuel, then the third is plugged. So yes i think its for the factory air assembly Mine has an edelbrock carb but im sure they have the same hook ups Last edited by Drewski23; 08-07-2013 at 11:57 PM. |
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#3 |
Registered User
![]() Join Date: Jul 2013
Location: Forestburg, Texas
Posts: 659
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Re: Carburetor Vacuum Lines
Wow, this is really early Q-jet.
The front one is (should) Venturi vacuum. Cap it off. The rear one, the picture is not very clear, should be manafold vacuum and it should be for the PCV system. This carb, I think is an early-mid 1960 model. Do us a favor and pull the air cleaner and take better pictures. I'm wondering if this is an early square bore Q-jet. 1959-1965 era.
__________________
Mark Jesus is the Way! 2003 2500HD CCLB Duramax/Ali (Clifford) 2014 2SS/RS black on black Camaro (Betty) 2006 Pontiac SOLSTICE silver/black (Lula-Bell) 1970 C/10 Short Wide (Peggy) 1964 C/10 Short Step (Hambone) RIP Jimmy Hamilton Thank you for the trucks |
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#4 |
Registered User
Join Date: Apr 2013
Location: Princeton, NJ
Posts: 40
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Re: Carburetor Vacuum Lines
For question #2, I was referring to the thinner hose that comes out of the carb near the choke and goes back up to the air cleaner. (I know that the big hose back there is the PCV, but what about this thin one?) Not sure if it's actually supposed to go back up to the air cleaner.
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#5 |
Registered User
![]() Join Date: Jul 2013
Location: Forestburg, Texas
Posts: 659
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Re: Carburetor Vacuum Lines
A: Venturi vacuum. Cap Off
B: PCV system Vacuum C: Thermostatic carb heat vacuum source. If you are still using the system keep this. If not... Cap Off D: ????? Cap Off
__________________
Mark Jesus is the Way! 2003 2500HD CCLB Duramax/Ali (Clifford) 2014 2SS/RS black on black Camaro (Betty) 2006 Pontiac SOLSTICE silver/black (Lula-Bell) 1970 C/10 Short Wide (Peggy) 1964 C/10 Short Step (Hambone) RIP Jimmy Hamilton Thank you for the trucks |
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#6 |
Registered User
Join Date: Jan 2013
Location: Bencia
Posts: 38
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Re: Carburetor Vacuum Lines
the small line coming off near the choke goes up to the air cleaner.
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#7 |
Registered User
Join Date: Apr 2012
Location: Henderson Nevada
Posts: 804
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Re: Carburetor Vacuum Lines
Here you go
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#8 |
Registered User
Join Date: Apr 2013
Location: Princeton, NJ
Posts: 40
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Re: Carburetor Vacuum Lines
Thanks everyone for your help. I'm going to get some plugs right now.
And mmiddle, here is the carb without the cleaner over it... do you know anything about it? ![]() ![]() ![]() -David |
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#9 |
Registered User
![]() Join Date: Jul 2013
Location: Forestburg, Texas
Posts: 659
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Re: Carburetor Vacuum Lines
I was wrong...or hoping I was right
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__________________
Mark Jesus is the Way! 2003 2500HD CCLB Duramax/Ali (Clifford) 2014 2SS/RS black on black Camaro (Betty) 2006 Pontiac SOLSTICE silver/black (Lula-Bell) 1970 C/10 Short Wide (Peggy) 1964 C/10 Short Step (Hambone) RIP Jimmy Hamilton Thank you for the trucks |
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#10 |
Registered User
Join Date: Jul 2013
Location: Mount Albert.Ontario
Posts: 119
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Re: Carburetor Vacuum Lines
I know it needs a good cleaning.lol
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