mickyb

Ok, may be a dumb newbie question but I need to know. What is this that I'm pointing at and what does it do, how do I clean it up

Thanks

kevdog442

The thermal vacuum switch is part of the Thermostatically Controlled Air Cleaner (TAC) System. It controls a trap door in the air cleaner snorkel which routes heated air from the exhaust manifold heat stove into the air cleaner, depending on the air temperature. This provides faster warmup and better cold engine driveability.

Allan R

That's the sensor that is hooked to the vacuum line for the thermal valve on the end of the snorkel (I believe it's labled 'Thermac') You don't clean it up, if it's pooched you replace it. They are reproduced, just not in GM green.

How it works: when the engine is started cold, there is high vacuum from the manifold that causes this sensor to close the valve on the snorkel inlet. This allows warmer air from the exhaust manifold to come up through the stove pipe and channel into the carb. The basic idea was to prevent icing the carb up in cold weather starts. Once the engine warms up and the idle comes down, the sensor then lets the vacuum operated valve in the snorkel to open and draw outside ambient air into the carb.

Here's an example of a repro from Supercars Unlimited. If you shop around you'll find the prices range from about 10.00 to 40.00 for the same part.

mickyb

Ok, thanks. It looks pretty craptacular. Mice made a home in the air cleaner housing and I'm sure that helped crud this up.

mickyb

Rock Auto has something similar, they call it "Air Intake / Charge Temperature Sensor". Is this it, sure looks like to be? They have it for about 5$

Allan R

Yup. Save some money and buy that. Don't worry about the color.

mickyb

Smarvelous!!! I appreciate your response. Just placed my order and snagged that last one on a closeout. Now with the rest of the housing/assembly/base or what have you, I could get away with sanding as much of the surface rust off and spray painting it.

47 Convertible

Your car, you can do whatever you want but sanding seldom removes all the rust. A better way is to have someone with an air powered blaster either bead blast or sand blast the whole housing inside and out plus the cap inside and out. Then sand with about a 150-200 grit to smooth it as much as possible. Prime and then finish coat. Someone that knows more than me can tell you what the original air cleaner looked like, i.e., shiny or satin finish and correct color. Quality work takes more effort but the satisfaction of knowing it was done right is worth it. My grandpa used to say "anything worth doing is worth doing right",

Allan R

Satin finish. Also don't forget to get the air cleaner decals for your application. I agree on the media blasting. For me it's a no brainer because I have the blaster and air supply setup for that.

re: sanding after blasting. Yes! Most folks don't realize that the finish is still crude at that stage and needs to be finish sanding. The good part about that is you really only need to get the large areas. Once you're finished with the sanding, clean the surface with paint thinner or metal cleaner before priming and painting. That will remove any oils that were on your hands when you last touched the piece. Once it's clean use latex or nitrile gloves to handle the piece.

Indy_68_S

Any ideas toward reproducing the white lettering "Service Instructions" silkscreen / stamp on the rear of the base?

Allan R

Are you talking about the orange/red bases with the service info? The only way I could see that happening is taking a photo of the original and having it laser cut at a vinyl place to use as a template. I don't believe anyone has done much if anything about that issue. Let us know if you have a lead on it.

Indy_68_S

Yep. This...


( Pic swiped from dnmfranco 's for sale post here....
https://classicoldsmobile.com/forums...-adapters.html )

I'm re-doing mine AC and that stamp was in a blistered paint area (looked like a carb fire as some point).

Looks like it was screen printed or ? .
The chebby guys have repro stickers to approximate it.

I'll bounce the screen print idea off a graphics buddy of mine and report back....

MDchanic

You could definitely reprint that, BUT it won't be easy.

First you have to take a picture of a perfect one (or take a picture of an imperfect one, and hand-fix it on your computer). The picture has to be perfectly dead-on, preferably with a long lens, to minimize distortion, and has to be lit very evenly.

Then you have to load your picture into Photoshop or something similar, and use the program to correct for the curved surface of the air cleaner, making all lines square and parallel.

Then you have to print out an exact-size positive on a transparency (you need a laser printer and special printable transparency medium).

Then you have to get a small, flexible silkscreen, designed for printing things on coffee cups, coat it with photographic emulsion, and expose the transparency onto the screen.

Finally, after washing out the image and curing it, you can print it onto an air cleaner using an epoxy ink and a small squeegee.
If all goes well, the next step is to set up a business doing this - you won't make much, but you'll get an occasional customer.

- Eric

Allan R

Au Contraire Eric, I disagree. Easy Peasy. Only thing that is a hiccup is getting permission to use the AC symbol. This doesn't need silk screening, just a negative transfer film to use as a template that is painted on. Computer generated graphic cutters will do this in just minutes.

MDchanic

You only need permission to use the AC symbol if you sell it to other people.
If you just use it for yourself, it's fine.

The original was done by silk screen, or possibly by some sort of rubber stamping process that gave the same result as silk screening. I'm not sure what you mean by "a negative transfer film to use as a template that is painted on," but whatever it is, maybe that would work, too.

- Eric

Allan R

Laser cutting using graphics. Cut away the imaging that would be 'painted' after the template is created. I guess the word 'negative' is the wrong approach. I should have referred to it more as a worded stencil. The backing side would have self adhesive to attach to the air cleaner prior to painting. Then just peel away the stencil - and voilą!

I seriously doubt that GM gave any thought to making a special radius correction for the application of this service info. They probably didn't think much of this stuff would last more than 5-7 years before it was crushed. I'll have to check and see if I have one of these older orange air cans that I can play with on this. BTW, I didn't forget about that T stat with directional indicators on it. Just haven't found it in the shed yet. When I do, I forget the thread it was mentioned, but I'll send it to your home email.

mickyb

The cover will look like this then. JK