BruceC

Hello all. The car is a 1978 Delta 88 Royale, 4.3L 260cid V8.
Recently had engine rebuilt and was looking it over today and found what looks like some type of connector that had vacuum lines hooked up to it at one time but the lines were cut off. The connector sits on the engine block just to the left of the alternator (facing engine from front.) It has what appears to be a short brass colored tube that fits into a small hole.
Photo one is the connector in question and photo two is where it sits on the engine.

Thank-you for the help.

henryk8398

Looks like a ported vacuum switch. Can almost guarantee it sits inside that fitting on the water crossover. The brass tube is a temperature probe.

I found this on rockauto's site, but it looks like you have 3 ports.

http://info.rockauto.com/getimage/ge...tex/7P1080.jpg

Is you emissions diagram still intact? That should tell you where the vacuum lines go.
If all else fails, try the chassis service manual or find another 260 car. If you run into one at a salvage yard, grab that vacuum switch and make a note of where the lines go. Who knows if they still make them...

It shouldn't be that complicated, I'm guessing you have some fittings capped off on your carb.

svnt442

It's a thermo vacuum port. Usually it cuts off of drops the amount of vacuum until the engine reaches operating temps. They can be used for the distributor or EGR valve.

78ChevOlds

I got my books at home and can get that info for you. I have a 78 260 V8 but can't tell you the actual name of it and what vacuum hoses are connected.

BruceC

Thank-you henryk. I figured that it was some sort of vacuum line connector. I was just concerned because it sits loose in the fitting. I will definitely look into getting a chassis service manual.

BruceC

Thank-you svnt442. I appreciate the info.

BruceC

Thank-you 78ChevOlds. If you get the chance, I would appreciate the info.

78ChevOlds

BruceC,

Officially it is called the Distributor Thermal Vacuum Switch (DTVS) and is only for the 260 V8 non Calif. The benefit is to give better cold engine driveability. It 'switches' after 150 degrees.

Looking at the switch from the side, the top port is the checked manifold vacuum, the middle port is to the distributor thru the SAVM (Spark Advance Vacuum Modulator), and the bottom port is to manifold vacuum.

On my car, both the top and bottom ports are tee'd into the vacuum lines connected to the CTVS (Choke Thermal Vacuum Switch) on the air cleaner. The middle is connected to the SAVM.

Hope that helps. Good luck,

Dave

BruceC

Dave,

Thanks very much for the info. It is indeed a big help!

Bruce

MDchanic

This may help, too:


1978 Olds 260 Vacuum Line Diagram

- Eric

BruceC

Excellent! Just what the MD ordered. Thank-you!