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12-28-2019, 10:21 AM
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#1 |
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Registered User
Join Date: Mar 2018
Location: Fort Wayne
Posts: 106
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What is this?
So I was looking at my carb this morning. Recently I've been curious about changing over to a Holley 2 barrel carb. Currently I have (or my best guess) a Rochester 2G. 1968 C10 with a 307 and manual 4 speed. Seems to be "mostly" original. Anyways, it's been hesitating here and there, on starts and stops. Considered a clean up and rebuild for the carb. Browsed replacing it with a new one just because. Basically considering all options. So upon taking a closer look at what I have, I notice on the back of the carb, there is a rubber hose, maybe 2 inches long, with something capping the end. I'm guessing this is some kind of vacuum line but where was it supposed to go? Is it that my simple little 307 isn't equipped for that kind of vacuum line? Is this the reason for when the vehicle hesitates?
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12-28-2019, 10:24 AM
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#2 |
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Senior Member
 
Join Date: Nov 2019
Location: Cocoa FL
Posts: 596
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Re: What is this?
Do you have power brakes?
__________________
Die with memories, not dreams. Not to brag, but I don't need alcohol to make really bad decisions. 1969 GMC Short Step Side |
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12-28-2019, 10:26 AM
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#3 |
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Registered User
Join Date: Mar 2018
Location: Fort Wayne
Posts: 106
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Re: What is this?
no power brakes
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12-28-2019, 10:28 AM
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#4 |
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Senior Member
Join Date: Nov 2019
Location: Cocoa FL
Posts: 596
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Re: What is this?
Then I would guess that is what the port is for.
__________________
Die with memories, not dreams. Not to brag, but I don't need alcohol to make really bad decisions. 1969 GMC Short Step Side |
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12-28-2019, 01:00 PM
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#5 |
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Registered User
Join Date: Aug 2009
Location: Bowser
Posts: 13,731
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Re: What is this?
The small short hose is likely a manifold vacuum port.
I see a vac hose by the valve cover. It could be hooked to a vac port on the front or side of the carb. The big hose is usually used for power brakes. You got more pics. Be interesting to see where the big hose goes. It might be your hesitation cause. |
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12-28-2019, 01:05 PM
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#6 |
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Who Changed This?
Join Date: Jan 2013
Location: Simi Valley, CA
Posts: 10,676
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Re: What is this?
The big hose should go to the PCV valve. The small hose- OP, did you used to have an AIR system (SMOG pump) on your truck? That hose would have gone to the diverter valve, I suspect, if you had that system.
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~Steven '70 Chevy 3/4T Longhorn CST 402/400/3.56 Custom Camper Simi Valley, CA |
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12-29-2019, 09:40 AM
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#7 |
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Senior Member
Join Date: May 2006
Location: Philadelphia, Pa. 19454
Posts: 9,761
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Re: What is this?
Do you have a Th350 or a 3 on the column?
__________________
Semper Fi...Uncle Sam, you da man All parts offered to help are free, unless otherwise noted Dont try this stuff in my build thread, unless you have 55 years of mechanical OTJ training SAFETY FIRST AS usual, off topic They say your mind goes second, can't remember the first Jim |
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12-29-2019, 01:49 PM
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#8 |
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Registered User
Join Date: Nov 2001
Location: Old Bridge,NJ
Posts: 838
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Re: What is this?
I think it's a vacuum used to recoup emission and maybe hooks up under and to the air filter. Power brakes use the manifold vacuum fitting just a few inches back from the carb on the manifold , I also think the TH 350 auto would use the same manifold vacuum fitting with two fittings, one for the PB and one for the trans. I'm sure there's more here that can confirm.
Happy New Year Last edited by NGN; 12-29-2019 at 02:07 PM. |
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