Choke Thermal Vacuum Switch

[Ericutlass]

I'm looking for this part for my 76 cutlass 350 engine.

When i bought the car the CTVS wasn't plug, there's no ref on it and i broke the lower pipe when i removed it from the intake manifold.

I'm looking for the ref or for someone who know where i could buy this part or someone who have this part and want to sell it.

Thanks
Eric

http://img130.imageshack.us/img130/7518/photo258bf4.th.jpg (http://img130.imageshack.us/my.php?image=photo258bf4.jpg)

[psquare75]

I might have one..

What's it do?

[Ericutlass]

Here is what my service manual says :

The L6 1bbl and all 4bbl carb (except the Omega 350) use a choke thermal vacuum switch to give a richer choke operation with engine coolant temperatures less than 57° (14°C) (80° - 27°C L6) . These carbs are equiped with two vacuum breaks. The choke thermal vacuum switch controls the vacuum to the carb, front or auxiliary vacuum break.

When the engine starts and the coolant temperature is greater than 57° (14°C) (80° 27°C L6), both vacuum breaks pull the choke to its leanest position. If the coolant temperature is less than 57° (14°C) (80° 27°C L6), the CTVS closes and prevents the vacuum break from pulling, giving a richer start and improved cold driveabvility.


http://img110.imageshack.us/img110/8339/dsc01149ms3.th.jpg (http://img110.imageshack.us/my.php?image=dsc01149ms3.jpg)

[442MUCH]

Hi Eric,

The part number is 419591 as of May 1981. This is the Thermal Vacuum Switch Assembly for all 1975-76 Cutlasses with the 350 and 455 engines.

Hope this helps,

Ken

[Ericutlass]

Ken,

Thanks for you help but i checked in a Tomco "pdf" file and founded the part number you gave me, but in this file, the switch is describe as a 3 ports switch, mine has only two ports and the scheme in the service manual shows only 2 ports too.

I have two vacuum switches on my intake manifold, on the left when you're facing the engine there's a 3 ports switch ( one of the port is plug to the distributor vacuum advance). The second is on the right of the intake when you're facing the engine and it's a 2 ports, the lower port is plug to the carb vacuum and the top port is plug to to the front vacuum break of the carb.

Are you sure 419 591 is the correct part number for the 2 ports switch ?

Thanks again for your help

Eric

Here's the link to the Tomco pdf file:

http://www.tomco-inc.com/Catalog/38thermal%20vacuum%20valves.pdf

[442MUCH]

Ken,

Thanks for you help but i checked in a Tomco "pdf" file and founded the part number you gave me, but in this file, the switch is describe as a 3 ports switch, mine has only two ports and the scheme in the service manual shows only 2 ports too.

I have two vacuum switches on my intake manifold, on the left when you're facing the engine there's a 3 ports switch ( one of the port is plug to the distributor vacuum advance). The second is on the right of the intake when you're facing the engine and it's a 2 ports, the lower port is plug to the carb vacuum and the top port is plug to to the front vacuum break of the carb.

Are you sure 419 591 is the correct part number for the 2 ports switch ?

Thanks again for your help

Eric

Here's the link to the Tomco pdf file:

http://www.tomco-inc.com/Catalog/38thermal%20vacuum%20valves.pdf

Eric,

I checked the book again. The only two port switch that is mentioned for 1975-76 is the EGR Valve Vacuum Control Switch. The number I gave you is correct for an E.F.E. Thermal Vacuum Switch Assembly (according to my book which is a 1964-76 GM F85 / Oldsmobile parts catalogue).

I went out to my car to see for myself. I have a Thermal Override Switch in the same place as your switch. It has an electric wire and no ports. I don't have a Thermal Vacuum Switch assembly.:confused: I do have a three prong switch on the opposite side of the manifold right behind the oil filler tube.

http://img.photobucket.com/albums/v417/vttedrm/Switch1.jpg
http://img.photobucket.com/albums/v417/vttedrm/Switch.jpg

[petrofyed]

i recently broke the 2 port vacuum switch on my 75 455 olds and i got one through o'reilly auto parts....the first place i went to the guy had no idea what the part was, but then when i went to o'reilly he pulled out the parts book and looked it up....it seemed to me that any 2 port vacuum switch that looked like that would work....and they had all different kinds, 1 port, 3 port, etc....

[Ericutlass]

Petrofyed,

Do you have 2 vacuum switches on your intake (1 with 3 ports and a second with 2 ports) or only one with 2 ports ?
If you have 2 switches could you tell me where the 2 pipes of the 2 ports switch are pluged please ?

Here's a link to a pic from my 76 olds service manual about the CTVS function and characterictics.

http://img201.imageshack.us/img201/1172/ctvs2xc8.th.jpg (http://img201.imageshack.us/my.php?image=ctvs2xc8.jpg)



I will check at o'reilly auto parts if they have a website.

Thanks
Eric

[Ericutlass]

Ken,


Here's a link to a picture from my 76 service manual about the engine vacuum hose routing.
You will noticed that each diagram use a 2 ports CTVS.

http://img154.imageshack.us/img154/2746/vacuummq9.th.gif (http://img154.imageshack.us/my.php?image=vacuummq9.gif)

Eric

[petrofyed]

hey!
i will check today when i go to lunch and see where they go....and i do not believe that you will find it on their website....you might get lucky but when i went in to the store they had to look it up in the parts book....

[petrofyed]

wow...did a search on www.oreillyauto.com and looked up 'vacuum switch' and this one popped up:
http://www.oreillyauto.com/EW3/DisplayTheParts.do?categoryIndex=0&didSearchFor=Vacuum+Switch&vehicle=1975OLDSMOBILECUTLASSSV8-455%207.5L&bid=1184243507881&cycleCount=1288

not sure if the 455 ported switches are the same as the ones on a 350.....this one is the one i got for mine...

[Ericutlass]

not sure if the 455 ported switches are the same as the ones on a 350.....this one is the one i got for mine...

The important thing is that the valve is of a "closed type valve" that it has 2 ports and that it opens when the coolant temp is at 57°F.

If on your 455 the lower pipe is connected to the manifold vacuum and the upper to the carb primary vacuum break, it's probably the valve i need....

Eric