Gaz Hog

What is this? Goes on the intake manifold of a 69 olds delta 88 with a 455. Two of the three ports are broken off

oldcutlass

Good question, however without a proper picture its hard to tell.

Gaz Hog

Should be up now. Technical difficulties.

BackInTheGame

Looks like a damaged 3-port vacuum switch. Not being familiar with the vehicle model, I have no idea what the ports would specifically connect to - probably one to the carb, one to a vacuum canister, and one to the air cleaner?

joe_padavano

It's called a Thermostatic Vacuum Switch. The purpose of the switch is to change the vacuum advance from ported vacuum to manifold vacuum if the engine starts to overheat. Since ported vacuum is essentially zero at idle and light throttle, there is no vacuum advance under these conditions. Changing this to manifold vacuum adds vacuum advance at idle, which lets the engine run cooler.

The top port should be labeled "D" for distributor (vacuum advance can). The middle port is "C" for carb ported vacuum tap. The bottom port is "M" for manifold vacuum.

The operation and hose connections are shown in section 6K Engine Cooling of your CSM.

jaunty75

Here's what one looks like that's NOT broken. $16.99 and available for your car at autozone. They call it a "ported vacuum switch."

http://www.autozone.com/engine-manag...mString=search

MDchanic

Also, note that any modifications to your engine (or personal preference) which cause you to run the vacuum advance off of manifold vacuum instead of ported vacuum will make this part unnecessary, and make you need a brass pipe thread plug from the hardware store instead of this switch.

- Eric

Koda

Or, if you're simply performance minded, de-hose the switch and leave it in there.

Gaz Hog

Right now it has an aftermarket intake manifold, hei ignition and a 4 barrel. I want to go back to all original, Including the original 2 barrel carb. So I can get a ported vaccuum switch and call it good?

BlackGold

Yup, and if it turns out that your engine likes manifold vacuum better than ported, you can always feed both the M and C ports with manifold vacuum instead of feeding the C port from the carb. Seems funny, but it will look more original than leaving it all unconnected.