would a disconnected dtvs/ported thermal vacuum switch cause hesitation while the engine is cold. because i noticed its broken and the vac lines are plugged. 260,2bbl

 

Hi. If it's the one to your vacumn advance on the distributor, Yes it will. Don't plug them, it is best to connect them together. One is a supply, the other goes to the intended vacumn controled device. Also, If you happen to find a new TVS, let me know. I need one as well. Hope this helps. Jim.

 

Do either of you have a pic of this part? I have a couple of things left over from my 260 to 403 swap. I may be able to help. If you can't post a pic here, you can email me at dreamsolds@yahoo.com. Let me know if I can help.

 

Hi. Here's a pic of a broken one, minus the connecting points. A number is pressed in the top. 3030951. Any help would be great. Thanks, jim.

 

i didnt plug the lines they were plugged when i got the car. i ordered a new dtvs from advance for 19 bucks. its part number pvs100

 

The one I have, has three points, not the two your's is showing. Mine screws into the top of the intake. If your interested, let me know and I can email you a pic.

 

mine has 3 also but on the vacuum diagram the top and bottom do connected so you could probably use a two port switch

 

Hi, what year engines are you guys talking here? The switch on my '73 engine is not connected completely or possibly correctly. Engine runs like crap when cold,(except when on fast idle) and idles rough even when warm. I suspect I have carb problems, but since this ported vacuum switch is integrated in the sytem(which includes EGR), I'm sure it plays a part. I'm looking into scrapping the whole system if I can't get it all working correctly.
Chumley

 

i have a 78 cutty with an olds 260 v8

 

I am having the exact same problem with my '73 delta 88 350. The engines performs sluggishly when cold. Someone has bypassed my dtvs and gone to a ported vacuum source on the carb. I think this should work, but I am at a loss why the car runs so poorly when cold.
This problem has been plaguing my delta. I have rebuilt the carb and have a new msd distributor and coil, so I am at a loss if it isn't the dtvs.

Thanks in advance,
Chris

 

The TVS should have no effect when the engine is cold. The sole purpose of this switch is to run full manifold vacuum to the distributor if the engine gets too HOT. You all have a different problem with your cold running issues.

 

If the vacuum advance pot is working properly, it will.

Choke would be the first place to look.

Did you adjust the choke?

I'm sure they look pretty.

Norm

 

Vacuum advance is working. Checked it with a timing light. The question was more directed at whether the dtvs "tunes" vacuum to the advance "pot" based upon running temp

Choke may need to be richened some.

I adjusted the choke to spec per the rochester repair manual

Definately matches the color of the car, which is why I picked it.

 

Chris - Are there any more hoses going to the bypassed valve?
If so, where do they go?

My 72 had a 'somewhat bypassed' TCS valve when I bought it. They hooked the disty right to manifold vacuum and left the ported vacuum hose on the valve with no other hoses on it. Under certain conditions the ported vac source would be sucking air through the open valve ports and caused issues. I plugged any unused ports.

Not sure how similar your dtvs valve works compared to the tcs valve...

Any vacuum leak (even small ones) will play more havoc with a cold engine...

 

Lady72nRob71-
Currently there are no vacuum lines going to the DTVS. My vacuum advance goes directly to the a ported vacuum source on the carb. A vacuum leak is a good place to start. I will check it out. Thanks.

 

I probably have one for both of your cars.
Let me know if you want me to start digging.

 

Thanks for the offer J-, but I just picked one up from NAPA.