thermostat vacumn fitting

CwbyEngineer · 08-20-2008, 10:48 PM

Back to the 81 Chevy K20 with 350, no air, and manual trans. What is the purpose of the 2 vacumn line adaptor on the top of the thermostat cover housing? Can I remove the adaptor and plug the hole or do I need to replace the adaptor as it is broken off between the two hoses? Am replacing the Q-Jet and stock manifold with a Holley off road carba nd Weiand dual plane.

mudseeker · 08-21-2008, 08:37 AM

i don't think those are vacuum lines, if they were then you be sucking up a lot of coolant in them. they are most likely bleeder valves, they're used to purge your system of air after you have lost fluid and refilled it. i have only seen these on compact cars though.

87c10slammer · 08-21-2008, 09:55 AM

no you dont need them. they are a way of temp controling something on your truck. if you break it al the way off a tthe nut youll see a spring and a metal disk or diaphram. i dont believe you need it for the new carb. as it will have an electric choke or mechanical one. i believe that is what is was used for

CwbyEngineer · 08-21-2008, 12:56 PM

Thanks, I'll just unplug the vacumn lines and leave it. They are vacumn lines as they connect to other vacumn lines. The new carb does have an electric choke so no need to connect to stock choke system. I'll let you know how it all runs in a week or so.

leolkfrm · 08-21-2008, 01:50 PM

They were part of the early air polution controls, It is a temp sensor that would open and close vacuum to the system. If you want to clean up the look use a housing with out the hole. You should be able to take all the garbage off, just hook to a live vacuum for the distributer. Remember to keep the PVC system to vent the crankcase

leolkfrm · 08-21-2008, 02:01 PM

Just another thought if you are going to pull the intake, you might want to consider a cam and chain, GM started designing air polltion control into the cams back then,such as retarded timing.

08-20-2008, 10:48 PM	#1
CwbyEngineer Junior Member Join Date: Jul 2008 Location: Western Nebraska Posts: 4	thermostat vacumn fitting Back to the 81 Chevy K20 with 350, no air, and manual trans. What is the purpose of the 2 vacumn line adaptor on the top of the thermostat cover housing? Can I remove the adaptor and plug the hole or do I need to replace the adaptor as it is broken off between the two hoses? Am replacing the Q-Jet and stock manifold with a Holley off road carba nd Weiand dual plane.

08-21-2008, 08:37 AM	#2
mudseeker mod-o-tator Join Date: Feb 2006 Location: michigan Posts: 4,508	i don't think those are vacuum lines, if they were then you be sucking up a lot of coolant in them. they are most likely bleeder valves, they're used to purge your system of air after you have lost fluid and refilled it. i have only seen these on compact cars though. __________________ member map add yourself alldatadiy why is it, when i push one for english, i still can't understand the person on the other end?

08-21-2008, 01:50 PM	#5
leolkfrm Senior Member Join Date: Mar 2008 Location: N.Y. Posts: 1,456	They were part of the early air polution controls, It is a temp sensor that would open and close vacuum to the system. If you want to clean up the look use a housing with out the hole. You should be able to take all the garbage off, just hook to a live vacuum for the distributer. Remember to keep the PVC system to vent the crankcase __________________ 4 wheels move the body 2 wheels move the soul

08-21-2008, 02:01 PM	#6
leolkfrm Senior Member Join Date: Mar 2008 Location: N.Y. Posts: 1,456	Just another thought if you are going to pull the intake, you might want to consider a cam and chain, GM started designing air polltion control into the cams back then,such as retarded timing. __________________ 4 wheels move the body 2 wheels move the soul

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08-21-2008, 09:55 AM	#3
87c10slammer Banned Join Date: Mar 2008 Location: levittown pa Posts: 2,197	no you dont need them. they are a way of temp controling something on your truck. if you break it al the way off a tthe nut youll see a spring and a metal disk or diaphram. i dont believe you need it for the new carb. as it will have an electric choke or mechanical one. i believe that is what is was used for

08-21-2008, 12:56 PM	#4
CwbyEngineer Junior Member Join Date: Jul 2008 Location: Western Nebraska Posts: 4	Thanks, I'll just unplug the vacumn lines and leave it. They are vacumn lines as they connect to other vacumn lines. The new carb does have an electric choke so no need to connect to stock choke system. I'll let you know how it all runs in a week or so.

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