Hello all. New to the site and so far loving it. I have scoured this site and several others and cant seem to find the solution to my problem. I bought a 1967 Cutlass (base) in August of this year and have been slowing working on her issues. (and learning as I go). I noticed the other day three vacuum lines disconnected. As you can see by the pic one, one is orange line color coded and comes out of a firewall grommet. The red line color coded line comes out of the AC/heater section. The third, quarter inch tube, comes out of the rear of the carb off the manifold and has a strong vacuum. When unplugged the car runs bad, popping and sputtering. When its plugged, runs smooth. Can anyone help on where these are supposed to be going to? Also, the heat/AC runs good with the two color coded lines not connected. The second pic shows the smaller vacuum hose coming out of the manifold going "up", towards the passenger side. It is visible in the first pic behind the orange color code coming out of the firewall.

 

Mine does not have a/c nor does it have that canister. I'm going to assume it's part of that system. What happens when you connect the hose from the manifold to the hose on the canister with the white stripe and the red stripe to the other line from the canister?

Yes the engine will run rough with manifold line open.

 

As far as I can tell nothing happens. Ive tried both and the car seems to run the same. I was told earlier that the manifold vac line may have been for the vacuum advance on the distributor, which has been changed out.

 

The vacuum advance comes off the carb, it should be ported vacuum stock. There is a metal line that runs to the modulator on the trans and it should be connected to a small manifold port. There just isn't that much vacuum stuff on that car.

 

You really need a 67 shop manual which has diagrams of all the vacuum lines. The larger line from the manifold is probably a feed line for the HVAC system and most likely attaches to a reservoir somewhere on the firewall. The metal can in your photo is a vacuum motor that controls functions inside your HVAC unit and the smaller lines are probably from the control panel. Vacuum leaks on these older cars are a major pain and cars with factory air are the most complicated, get a manual.

 

Thanks all. I'll look for a manual.

 

I have a manual that desribes the location and color of vacuum lines.. If you would like I could scan it and send it to you or maybe post here. I just finished my car and spend some time locating the vacuum lines correctly.

 

Thanks Montana but I think I figured it out. Due to a carb change from rochester to edelbrock, i think it was an extra. But if you want to scan onto the site Id appreciate the extra info. Thanks again.

 

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Therein, you can access the factory service manual. I believe. Probably a pdf or something like that. Of course, a paper copy can be obtained via feepay or similar auction or sales sites.

The larger rubber tube looks like it might be for the power brakes. That is supposed to be a steel line out of the 90 degree adapter on the intake for a foot or so, then rubber over to the check valve on the booster.

 

Yeah I went there and found some good info. Couldnt find the exact line tho. But that is a great site.

 

This is out of a wiring diagram manual that I have. It shows the AC circuit but not the engine vacuum. The brake vacuum on mine is from a 90 deg adapter fitting on the manifold then a rubber hose to the brake vacuum booster check valve. I have had this car since 1970 and have never seen a steel line starting out. That doesn't mean that some cars didnt come with that arrangement.
the transmission line is hooked to the carburetor base plate tube. I don't know if that is right as it is not modulated that way but it works. I was told by a mechanic that it needed raw vacuum so that is how I did it.

 

That is correct. The trans vacuum modulator requires straight manifold vacuum, NOT ported vacuum.

 

Thanks Joe.