Olds luvr

Hello all,

As the winter projects begin on the convertible another part I am unsure of where to find is the ported vacuum switch. It seems that the aftermarket ones do not have the connectors on the top. Where can you find these and if not what are the options? Mine has a busted port (the very bottom one closest to the manifold)

Does anyone have a used one for sale?

Thanks as always!!!!

ent72olds

I see them on e-bay quite often...

Olds luvr

I have been looking but have not found any on there in a couple months or so and just wondering if there are other options. i have even considered trying to repair that port as that is the only this wrong with mine

New'n72

Olds luvr,

Are you speaking of the Distributor Vacuum Control Swith, with the one port in the center of the can on top and three ports on the shaft?

Olds luvr

Yes that is the one....Here is a picture just to be clear

Thanks,

New'n72

I have a 1972 also and I wanted to replace this switch but have yet to find a source. Mine is not necessarily bad ( I wanted a spare) but if this is the switch you are asking about, I was told that it was only used on the 1972 model year cars and finding one will not be easy. Probably a take-off from a parts car would be the easiest way to find one.

I have yet to see one on E-Bay.

There are ways to baypass portions of this switch but you will have to talk to someone more knowledgable about this than I. I know it can be done because it was bypassed on mine by some mechanic years ago and I put it back to original when I got the old girl running again, last year.

Olds luvr

Thanks for the reply. i wonder if mayber tyring to repair mine may be the best bet as of right now the port is open with no vacuum line running to it as it was busted off flush with the shaft when I bout it and there are no capped lines or open lines so I am sure that I have a leak somewhere and maybe that is why the car is very sluggish at a start?

Any other Ideas?

New'n72

I don't have a way to scan the page from the 1972 Olds Service manual so I'll try and do this with words.

The bottom port on the shaft goes to the manifold. It is labled Port - MT

On my engine there is a small 5 or 6 inch hose connected to this port on the switch that runs to a "T" connector. The right side of the "T" (looking at it from the front of the car) goes to a fitting, right/front, of the carburator, on the engine manifold.

The left side of the "T" runs back towards the FireWall.

If it was a little nicer weather here I would back it out of the garage and try and get some pictures but it's cold and I'm nursing a cold so......

Hope this helps?

Olds luvr

No problem I appreciate the help none the less. I guess another thing missing from mine would be the "T". I assume yours is all original and the T is right into the manifold?

New'n72

This is a digital photo from the Service Manual.

I appologise for the lack of clarity but it was the best I could do.

I think you can read everthing. The drawing is not in perspective. The attachment to the manifold is over on the right front of the carburator but at least you can see where the ports go by name.

Vacuum Switch.jpg

Olds luvr

Ok Thanks,

So The T is just a plastic one in the lines. I guess I will add to my projects a complete vacuum hose and routing as I do not believe mine are right. i am not sure that the original owner had going on but there is no t and the busted port is just open.

here is a question that may sound dumb but in the picture it say "to modulator"....What modulater are they refering to?

Thanks again

New'n72

Somehow I just knew you would ask that question.

I don't have a clue.

I will copy the written discription out of the service manual but I can tell you now the written discription does not mention the "modulator".

If it ws a bit warmer and I felt a little better I would pull the air cleaner and snap a couple photos. Maybe tomorrow or sunday. That way you can see where the hose goes and we don't have to worry about 'names'.

Text discription to follow.......

Allan R

Sorry, I posted wrong information, so i deleted it.

New'n72

Ok, here's the text from the service manual. and a photo of the switch with the ports labeled.

DISTRIBUTOR VACUUM CONTROL SWITCH

All cars except 350 cu. In 2Bbl. Manual transmission, non-A/C cars will have a distributor control switch assembly. This unit is used to advance the ignition timing when the transmission is in third or forth gear or when high coolant temperatures are encountered at idle.

With the transmission in first or second gear the solenoid is energized, the valve plunger is sealing off port “C” (carburetor), opening port “V” (vent) to atmosphere depleting any vacuum that might be present in the vacuum advance unit. In third or fourth gear, the solenoid de-energizes allowing the valve plunger to move down sealing off the vent port. When this happens, vacuum is directed from the carburetor through port “C” and out port “D” to the distributor vacuum advance.

When the engine coolant temperature reaches 210 degrees F, the valve plunger begins to move upward sealing off the vent port and opening up the port “MT” (manifold). At 218 – 224 degrees F, full manifold vacuum is directed to port “D” (distributor) and the vacuum advance unit regardless of transmission mode.




Vacuum Switch 002.jpg

J-(Chicago)

Do a search on here for: TCS or T.C.S.
(transmission controlled spark)

The modulator is on the transmission, to vacuum control the shift points.
There should be a metal line going from the trans modulator to the top of the intake manifold near the distributor somewhere.

Olds luvr

Thank you J. I do have that line running from the trans connected to the manifold. Is it supposed to run from the trans to the vacuum switch or to the manifold?

New'n72

The metal line runs up to the top of the engine. I can see where the hose connects to it without removing the air cleaner. A short section of hose connects it to one side of the "T" connector. The other side of the "T" goes to the manifold and the post of the "T" goes to the bottom port on the switch.

That first photo I attached show this.

Olds luvr

Ok, Looks like I need a T for my manifold as well as the modulator line just runs into a single port on the manifold.

So looks like I was right about having to do all the vacuum lines as who knows what has been modified.

J-(Chicago)

I have 2 extra TCS units here in my garage. Since they were a 71-72 only option, they are fairly rare. I have seen them go on Ebay for over 120 bucks. You don't NEED them, but folks who are sticklers for perfect restorations on their cars will pay top dollar for them so their car will be factory correct.
I suppose you guys need to decide if your cars are going to be trophy hunters, plain old drivers, or race cars. That will help determine if you need to replace yours or just eliminate them all together.

Olds luvr

J,

That is a very good question and I know I have to figure that out. When you say you have the tcs are you referring to the vacuum shitch or the silenoid on the tranny. i hear that switch called a few different names so i want to be sure and PM me and let me know what you want for one.
In addition if I bypass it what has to happen?

J-(Chicago)

Here you go.
https://classicoldsmobile.com/forums...-solenoid.html

The transmission modulator is nothing special. a new one at the local auto zone probably sells for 10 bucks. The 4 port switch is the rare piece.
As far as price goes, I'm not sure what to sell them for yet. I figured I'd put them up on ebay and let the country decide what they're worth. The economy is n't the best, and maybe people will think twice before spending hundreds of dollars on unnecessary parts, maybe not. I don't even know if they work yet, because I always just take them off and bypass them. I've probably thrown away 10 of those things in my lifetime. You should have seen my face when I saw it sell for over $100.
I was mad.... in a confused sort of way. Why in the world do people want THAT thing? Whatever. If it makes someone happy I guess.

People think I'm a moron for fixing 80's Delta 88s Just one of those aspects of life that are never quite understood I suppose.

johnspd22

Just saw one on ebay for $500. Holy S..t! It was new NOS, but come on.....

Allan R

Some people figure that NOS is worth more than gold. It all depends on the part and what you're willing to pay. I saw one of of these sell before XMAS NOS for around 85.00, so $500 sounds ....a LOT high. If the seller wants that much he's in the hereafter category. "He'll still be hereafter I've decided to buy something else for less money".

johnspd22

He was kind enough to throw in the shipping for free. What a guy!

I just bought one for $25 bucks. Going to see if I can get the top solenoid cover replated. Looks like the top was press fitted on @ underside. Dont know how easily it will come off or go back on.

johnspd22

Does anyone know the actual function of this switch. It appears in it's un-energized state, it allows vacuum (under the throttle plates) to pass from carb to distributor vacuum advance.

It also has a vacuum source above the throttle plates and another vacuum output to the transmission. I have tested (3) of these switches I have and none appear to be working. They look nice and original, just wondering the net effect of the above on drivability etc.

Any info on the above is appreciated. Thanks.

Lady72nRob71

This was just an early emission control.
Most people bypassed it when it went bad, as no exact replacement were made.

Here is good explanation of it and how to bypass it if it is broke:
https://classicoldsmobile.com/forums...ol-switch.html

Here is another good explanation of its function:
https://classicoldsmobile.com/forums...s-w-350-a.html

johnspd22

Thanks!

leadfoot067

i have that switch..its on the motor in my car now...you shoulda made a list...lol ohh and i have no use for it...

2blu442

I've got a couple parts motors with these on them, but I've also destroyed a couple trying to remove them. When I put a wrench on instead of the threads giving I'm crushing the fixture. I've tried soaking them with my favorite solvent and no luck. Any suggestions?

Cutty Man, are you needing help with the routing of vacuum lines?

MDchanic

Could you possibly be just a bit more specific?

- Eric

Bluevista

You do it the same way a plumber would do it, you remove the manifold from the fitting.
Take a BFH and smash the cast iron around the switch it until it breaks away and the thing comes right out.
The switch is worth more than most stock cast iron manifolds and the shipping's a lot cheaper without a manifold hooked to it.

The modulators are those guys that keep an eye on the site here.

2blu442

That sounds like a storyline for a redneck youtube video!
1) how to remove stubborn fitting?
2) take sledgehammer and start swinging!
3) stand clear of flying metal!



I'm such a packrat I don't know if I could bring myself to breaking up the large boat anchor for the switch!

joe_padavano

Funny you should mention this. A couple of years ago at Carlisle I bought what must be the rustiest 350 Olds intake for $5, only because it had a TVS on it. Don't know if the valve is functional, but the intake makes a nice doorstop now that the valve is removed. I let it soak with penetrating oil for several days before removal.

Allan R

Here you go. NOS

Bcd7ylQmkKGrHqUOKiUEq5eCrQBK0ldPp2Q_12.jpg?t=1301078011

Swede98

Hello Allan I also need that vacuum switch mine is broken do you now where I can find one ? Thanks Jerry

Allan R

Best thing is to watch the web. If you find someone whos parting out their 71/72 offer them 10.00 for the part 'undamaged' when removed. Chances are you'll get a bite sooner than later. These were only on the 71/72 350 cars. I 'won' one of these on ebay last year for .99 cents. That's right .99 cents! Then the seller renegged and said he wouldn't ship it to me because I live in Canada. His auction said he would ship anywhere. What a bad loser! Filed a dispute but never ever got my part. If I see any floating around, I'll PM you.

Swede98

Hello Allan yes its seems like hard thing to find this thing. Do I really need to have the original switch, they sell new ones on the web but then they only have 3 connections ? Thanks if you see one old just tell me thank you Jerry

Allan R

The info on the switch is that it's used to control advance on the distributor when the engine is either hot, or being driven in 3rd gear. See page 6K-9 of the 1972 Oldsmobile Chassis Service Manual. There's also a picture on page 6K-7 that shows the hook up for vacuum lines.