Nighthawk

The vacuum hoses on this car were not all hooked up right when I got it and to make matters worse I took everything off and left it off for a year. So I'm struggling to get it all together. After examining the diagram in my manual I have discovered that I need a CTVS, DTVS and VRV. Does anyone know what those do or where I could get them? I actually have one of those items but don't know if it is the ctvs or dtvs. It appears to be some sort of temperature controlled valve. In the diagram the VRV appears to be some sort of diaphragm? Any tips are much appreciated. Oh, and if anyone knows what TACS stands for that would be helpful

Nighthawk

Okay I found out that CTVS and VRV stand for:
Choke Thermal Vacuum Switch
Vacuum Regulatory Valve

I'd still like to know what these do and where I can get them though?

joe_padavano

We'd like to know what year, model, engine, and carb you have...

Nighthawk

aha, that would be helpful wouldn't it My bad. Its a '77 cutlass 442 with a 350 V8. All I know about the carburetor is that its a 4bbl. Attached is a diagram of the vacuum hose stuff with all three items pictured.

Nighthawk

From another thread I am picking up that the CTVS may only have two ports instead of three as pictured in the diagram. Would this make sense? I have a two port valve on the right side of my engine but did not think it was the CTVS because it only had two ports. Any thoughts?

I've attached a picture of the engine with several things circled. I believe the CTVs may be the orange thing in the front and the TACS is one of the two ports in the back?
Thanks

MDchanic

Might this diagram be more helpful than the diagram that you posted, which shows fewer components than you have?




(Here is the one you posted: )


- Eric

Nighthawk

Great! That is helpful. Why didn't the diagram I have show all that? Its from a '77 all series manual.
So the orange two port thing on my engine is the egr/dtvs.
I checked at the local Federated Auto Parts store and they did not know what the dtvs, ctvs, or vrv were or where to get them. So I'm still stumped.

Nighthawk

Another question. Attached is a picture of the carburetor front, yet I don't see any ported vacuum port on the right as in the diagram? This is before the carb was removed.

MDchanic

Which manual? Pretty much anything other than the actual factory service manual (I don't know if it was called the Chassis Service Manual in '77) is likely to be unreliable for this sort of information.


But aren't they here in the picture? I'm confused.




I agree that it seems to have at least one less port than the diagram shows.
Are you sure it's the original carburetor?



- Eric

Nighthawk

Eric,
In the picture the orange thing is the egr/dtvs (I think) but there should be another dtvs (still don't know what that stands for. Of the two ports in the back one goes to the vacuum booster for the brakes and I believe the other must be the one labeled as TACS in the diagram. And no I'm really not sure if the carb is original. How do I figure that out? I want to actually understand what everything does before I put it back on.

MDchanic

Yes, it looks like there should.
DTVS stands for Distributor Thermal Vacuum Switch.


Check the number on the side - you can look it up on line or post it up here and one of us should be able to tell you.

Unfortunately, I know next to nothing about these emission controlled engines, so I can't explain anything specific about it.
I would recommend the factory service manual, which generally has an excellent explanation of the function of each of these components.

- Eric

Nighthawk

Would a 78 pontiac sunbird all Gm 151 engines distributor thermal vacuum switch fit on my 77 cutlass? Its advertised on ebay as part #546896.

Nighthawk

I checked the carb and it is a Rochester Quadrajet and has the following numbers on the side:

17056250
1056 AHA

So to recap, I am trying to understand how the vacuum hoses should be hooked up:
1. I have the egr-tcv, egr/dtvs, ctvs, and pcv stuff.
2. I do not have the dtvs(the hole in the block for it has a plug instead) and tacs(?) and I appear to not have all the same ports on my carb as pictured in either diagram posted above.

Thanks again for the help.

P.S. I have at least two fewer carb ports than those pictured in MDchanic's diagram.

MDchanic

Looks to me like a carb for a '76 Olds 350 without A/C, made on 14 April, 1976.

- Eric

Nighthawk

Thanks, Eric. I'm pretty sure I got those numbers right but they were kind of hard to read
Anybody have a vacuum hose diagram for a 76 olds or would that be the same as the 77?

MDchanic

I can't find a '76 diagram, but I'm sure one is out there. It is probably different than '77 - they changed them constantly.

Remember, one solution is to dispense with all of the emission control crap, use a carb. and distributor set up for an earlier car with similar displacement, compression, and cam characteristics, and don't worry about it.

- Eric

Nighthawk

I guess I dispensing with the emissions stuff would be a possibility, but I'm leaning towards trying to get everything hooked up as close to original as possible. Wouldn't removing the vacuum hoses reduce performance quality or is it the other way around?

MDchanic

Yes, just removing he hoses would probably make it run worse (remember, I'm not an authority on these years), but replacing the carb and the timing components with ones that are calibrated for an earlier engine should work fine.

- Eric

Nighthawk

Thanks for all the help. Here's a 1976 vacuum hose diagram I had found. It looks a lot better

76oldswarrior

On my 76 with a 455. I capped the EGR and just run full manifold vac to trans mod and ported to the dist. I dont have any of those switches. The ports on the intake have plugs in them. You could hook it up like this to run the car till you get it all figured out. Thats if your trying to keep it original.

98regency

Hi

I also have a problem with a vacuum hose. It's the hose from the thermatic sensor mounted on the air cleaner to the vacuum break... Can't find the vacuum break.
Can someone send me a pic with the right connected hose?

On the picture there should be a hose on the second port of the thermatic sensor.




please help.. 98regency

98regency

push..
no answer?