'70 LS5 a.c. vacuum source

**Jim T.** · August 10, 2002, 08:52 AM

Re: '70 LS5 a.c. vacuum source

Jerry I am going to just guess before I go and look at my 70. Could this hose go to the water shut off valve?

**G B.** · August 10, 2002, 10:26 AM

I'm looking for the vacuum feed

Jim, I appreciate your response, but you're talking about a different hose.

The hose I'm trying to connect takes vacuum TO the controls in the console. From the console control valve the vacuum is then directed back out to the various a.c. system diaphragms through different hoses, including the one to the water valve.

**Jim T.** · August 10, 2002, 02:32 PM

Re: '70 LS5 a.c. vacuum source

I did look at my car and two hoses come across the rear of the firewall on my 70 and run under the vacuum motor that operates the windshield cowl. The two hoses are together and are tape around them right under the vacuum motor pie pan. One of these small hoses goes to the water valve and the other goes through the firewall cowl and then connects to a vacuum motor that opens and closes a valve in the fender that is used for the air conditioning. On MAX air it is closed to prevent cowl air from being used in this air conditioning mode.

**G B.** · August 10, 2002, 03:26 PM

You're in the right area

Jim -

Those are two of the five hoses that leave the center console a.c. control valve to take vacuum to diaphragms.

The hose I want to connect is the hose that takes vacuum from the engine to the center console control valve. This is a tiny 1/16" hose like the other a.c. hoses. It enters the firewall right behind the distributor vacuum canister. I'm guessing that it tees into a much larger vacuum hose near the distributor that eventually leads to the vacuum fitting on the intake manifold.

**Geoff C.** · August 11, 2002, 02:52 AM

Re: You're in the right area

Jerry,
It tee's off a large Yellow stripe vacuum hose. That Yellow stripe hose runs between the wiper door relay valve and the T-pipe feeding the reserve tank. It is cut close to the big firewall grommet and that bastard sized T-pipe is installed.
Geoffrey

**G B.** · August 11, 2002, 07:00 AM

Ahhhh...

Geoffrey -

Thanks for the help.

The wiper door relay on this car is mounted on the firewall near the brake booster. So the yellow stripe hose to the wiper door relay makes a big loop behind the distributor and at the passenger side of the loop is the bastard tee for the tiny a.c. hose connection?

Jerry

**G B.** · August 11, 2002, 09:35 AM

I understand

I'll call Debbie tomorrow to order one of those bastard tees (#2771222). I'll put it in the large main vacuum hose (to the tank) near the wiper door relay on the driver's side. I'll run a two foot long, 1/16" extension hose from the little a.c. hose to get to it.

**Geoff C.** · August 11, 2002, 01:12 PM

**Jim T.** · August 11, 2002, 02:07 PM

Re: I understand

Jerry glad Geoffery has your problem solved. Looking at my 70 this morning after reading Geoffery's post I found the vacuum supply rubber hose coming from the vacuum supply tank rubber hose that goes to the relay valve. My supply hose has two tees in it. The tee closest to the tank supplys vacuum to the headlight relays. The next inline T provides the connection for the air conditioner vacuum supply. The air conditioner vacuum supply rubber hose on my 70 travels from the T under the windshield wiper washer/motor and goes into the firewall throught a gourment that has the other two vacuum lines coming out going to the water valve and the other line goes to the vacuum motor that closes and opens the cowl air supply.
If you need a measurement from the relay to put the T in your vacuum hose I will measure it for you.

**G B.** · August 11, 2002, 02:58 PM

Please be gentle with me

Geoffrey and Jim -

Geoffrey, I assumed View B (from C60 Sheet E4 of the 1970 AIM) to be the outdated 1969 design. It shows the a.c. vacuum source line tieing into a large yellow stripe hose on the passenger side. There is no such hose on a '70 with the wiper door relay next to the brake booster. That's why I'm adding an extension on the 1/16" a.c. hose to take it over to the driver's side near the wiper door relay. I also disagree with the placement of the two firewall grommets shown in View B. I think they're drawn in opposite positions from the true 1970 firewall layout.

Jim, please measure the yellow hose distance from the wiper door relay to the tee for the a.c. line. Also, does your little a.c. vacuum source line have a 1/16" extension hose attached to it starting about 6" from the firewall and going to the yellow hose tie-in?

Thanks for the warning about the different tee configurations. Actually, I think the current version will fit better in this situation.

**Jim T.** · August 12, 2002, 02:00 AM

Re: Please be gentle with me

The hose that goes from the relay valve to the T is 3 1/4 inches on my 70. The hose that attaches to the other end of the T that goes to the other T for the headlamps is 10 1/2 inches long.
The vacuum supply hose appears on my 70 as one piece going from the T running across in front and laying on the windshield wiper motor. So much stuff grouped together behind the distributor could not seek it out, but from the gourment it comes out of in the firewall to behind the distributor it appears as one rubber vacuum hose from the T to the firewall gourment.
There is a very small spring clamp that secures this vacuum hose to the T connector.

**G B.** · August 12, 2002, 06:16 AM

Thank you both

I appreciate the time you two spent researching your answers. I've got a good plan now that will get the job done.

'70 LS5 a.c. vacuum source

'70 LS5 a.c. vacuum source

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