| Thermostatic Vacuum Switch [message #165769] |
Sun, 08 April 2012 15:51  |
Jon payne
Messages: 495
Registered: May 2008
Karma: 1
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Hi all...Happy Easter!
One of the ports on the TVS has broken off. Does anyone have a PN for this so I can procure locally? I know JimK sells but would like to pick one up tomorrow if possible.
Thanks,
Jon
Jon Payne
76 Palm Beach
Westfield,IN
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| Re: Thermostatic Vacuum Switch [message #165773 is a reply to message #165769] |
Sun, 08 April 2012 16:28  |
Dennis S
Messages: 3046
Registered: November 2005
Karma: 2
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Senior Member |
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Jon,
Autozone, Part Number: E940
Dennis
| Jon Payne wrote on Sun, 08 April 2012 15:51 |
Hi all...Happy Easter!
One of the ports on the TVS has broken off. Does anyone have a PN for this so I can procure locally? I know JimK sells but would like to pick one up tomorrow if possible.
Thanks,
Jon
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Dennis S
73 Painted Desert 230
Memphis TN Metro
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| Re: Thermostatic Vacuum Switch [message #165774 is a reply to message #165773] |
Sun, 08 April 2012 16:30 |
Dennis S
Messages: 3046
Registered: November 2005
Karma: 2
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Senior Member |
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Jon,
And before someone else says it -- many have eliminated the TVS, and have valid reason for doing so -- but because I want too, I still use one.
Dennis
| Dennis S wrote on Sun, 08 April 2012 16:28 |
Jon,
Autozone, Part Number: E940
Dennis
| Jon Payne wrote on Sun, 08 April 2012 15:51 |
Hi all...Happy Easter!
One of the ports on the TVS has broken off. Does anyone have a PN for this so I can procure locally? I know JimK sells but would like to pick one up tomorrow if possible.
Thanks,
Jon
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Dennis S
73 Painted Desert 230
Memphis TN Metro
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| Re: Thermostatic Vacuum Switch [message #165776 is a reply to message #165769] |
Sun, 08 April 2012 17:10 |
zhagrieb
Messages: 676
Registered: August 2009
Location: Portland Oregon
Karma: 0
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Rumor has it that if you don't live in California you don't need the switch. You can bypass it.
Glenn
Glenn Giere, Portland OR, K7GAG
'73 "Moby the Motorhome" 26'
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| Re: Thermostatic Vacuum Switch [message #165778 is a reply to message #165769] |
Sun, 08 April 2012 17:51 |
JohnL455
Messages: 4447
Registered: October 2006
Location: Woodstock, IL
Karma: 12
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It can be circumvented, but in my opinion is still good to have in an overheat situation in stop and go traffic. That's what it was in there for, to apply full manifold vac at idle in an overheat situation and at all other times to provide ported vac to the dist vac adv. That's all it does. Not exactly rocket science.
John Lebetski
Woodstock, IL
77 Eleganza II
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| Re: Thermostatic Vacuum Switch [message #165780 is a reply to message #165769] |
Sun, 08 April 2012 18:19 |
Ken Burton
Messages: 10030
Registered: January 2004
Location: Hebron, Indiana
Karma: 10
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Jon,
Get rid of the TVS. It is useless. Most do not work correctly after all these years and there is no practical way to test them except by over heating the engine.
It's purpose was to raise the engine idle speed to provide more air flow if the water temperature exceeded something around 220 F (104 C) degrees. If the engine is not idling it does nothing. It has nothing to do with emissions.
The TVS has 3 ports. One runs to a port on the carb. Attach that carb port hose direct to the hose going to the distributor. The remaining hose goes to a "tee" in the vacuum line. Remove that hose and remove the "tee".
You are finished.
From the internet:
Coolant temperature override
Also referred to as a Temperature Vacuum Switch (TVS) or Thermal Vacuum Valve (TVV). The CTO switch measures coolant temperature, usually from a passage in the intake manifold. It was commonly used starting in the 1960s for switching the vacuum advance from ported vacuum to manifold vacuum at high engine temperatures to promote cooler idling.
If you insist on replacing it and can not find one locally send me a note. Somewhere around here I should have the old one I removed from my engine years ago. Mine was bypassed by a PO and I removed it completely when I repainted my manifold. I can not guarantee it works since I never used it but it will fill the hole in the manifold should you choose to remove the old one and make it look pretty. Mine has a brass pipe plug in it.
Ken Burton - N9KB
76 Palm Beach
Hebron, Indiana
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| Re: Thermostatic Vacuum Switch [message #165787 is a reply to message #165778] |
Sun, 08 April 2012 20:43 |
Bob de Kruyff
Messages: 4260
Registered: January 2004
Location: Chandler, AZ
Karma: 1
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| JohnL455 wrote on Sun, 08 April 2012 16:51 |
It can be circumvented, but in my opinion is still good to have in an overheat situation in stop and go traffic. That's what it was in there for, to apply full manifold vac at idle in an overheat situation and at all other times to provide ported vac to the dist vac adv. That's all it does. Not exactly rocket science.
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A great reason to have full manifold vacuum all the time if you don't need to smog it..
Bob de Kruyff
78 Eleganza
Chandler, AZ
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| Re: Thermostatic Vacuum Switch [message #165788 is a reply to message #165780] |
Sun, 08 April 2012 20:47 |
Bob de Kruyff
Messages: 4260
Registered: January 2004
Location: Chandler, AZ
Karma: 1
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Our favourite argument--get rid of it since the ported vacuum chokes the engine at idle. The reason the valve gives full manifold vacuum at idle is not only to increase idle speed but also to allow the engine to run more efficiently at idle and reject less heat--read the manual.
Bob de Kruyff
78 Eleganza
Chandler, AZ
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