VCCA Home Forums TECHNICAL - 1945 AND EARLIER 1933-1936 1935-36 Exhaust Manifold Heat Control Valve

I was wondering if anyone knew if the Springs on the Heat Control Valve on the Exhaust Manifolds on a 37-65 were different than those on 35-36's. The Filling Station shows a Spring for a 37-65 but don't know if it will work on a 35-36. I need two for 35-36's.

The 1935 and 1936 are different.

Jon, if you cant find the spring send 35Mike a note he may have an extra available.

Does the filling station list the small spring that goes on the back of the manifold for the 207?

I figured the 35-36 Springs may be different. I guess they won't work either? The Filling Station does not list the Spring on the back and I don't know what it looks like. But I've been told I should be able to find it at a Local Hardware store.

What spring at the back of the manifold are you refering to ?

Are there more than one spring on the back of the Manifold because none of my cars have any.?

There is a small hole in the lever/ weight at the backside of the manifold. There is also a pin for hooking the other end of the spring. The spring must be short and weak.

Mike

My Dad started taking manifolds apart to build one with a working flapper for his 36 truck.

Here is where the unknown spring goes on the engine side of the manifold. We think it ran from the post on the manifold to hole in the weight.


In the process of taking a bunch of these apart he found that some have round weights and other have square. Some of the spring covers have cut outs and others do not.




Does any one know what this small spring inside the cover is for? It was in the three that we had off to look at.

It has been awhile since I rebuilt mine, but I think It Is called an anti-rattle spring. Yours Is broken, since It extends across the hole and inserts into the slot on the shaft, If I remember correctly.
Richard

Very good pictures. These will help me a lot in rebuilding mine.

Sam, Remind your dad that several years ago I sent him a piece of SS tubing that works great for the manifold bushings when you use a 7/16 " SS bolt for the shaft.
Richard

Wow... great timing. I just took mine apart earlier this afternoon. Or, shall I say "Broke" it this afternoon.

With the engine in the car and running. How can I free up the Control valve?

I used penetrating oil and gentle turns... but I still broke off the screen that held the cover on.

What do I do now? Does it matter if the valve froze in the open position? And how could I tell?

I have been working through overheating problems on my 36 Standard, and have learned a lot from many posts. I thought I would check to see if the heat control valve was working, and found that it would "move" when I rotated the screw on the shaft on the outside of the spring. But when the engine was at operating temp, it never moved. So I pulled the intake manifold and found that this "spring" on the backside was missing. Without this spring, the freely moving "flapper" is in the hot position (horizontal allowing exhaust gas to pass through. If there was a spring as discussed, then the flap would be in the bypass, or "cold" position when the engine was cold. With engine heat, this flapper will then move to the hot position, as the thermostatic spring opens; and will open against the pressure of the rear spring. Since this spring doesn't seem to be available, maybe a SS spring from the hardware store will work?
I would appreciate anybody's input on this.

I wonder if the 1937-1962 spring could be made to work?

Looking at the picture in the 1935 parts book and the picture in the Chevs of the '40's catalog they appear to work in the same direction. Looks like it would be worth a try.

Jonjet, the spring that was talked about on the backside of the manifold looks like this:



As you said, a hardware store should have a replacement that will work.

That is only an anti-rattle spring....I am sure he is talking about the thermostatic spring.

The original question was about the thermostatic spring but there was also a question about the anti-rattle spring clip inside the cover plate, and the spring that was connects to the weight.

I guesse I missed that.

Gentlemen, thanks for the responses. The photos are very helpful. It was difficult to explain what I have, but I DO have the thermostatic helical spring under the front cover, and the anti rattle spring is missing. HOWEVER, from the picture I see that the "flap" is open when cold, and the thermostatic spring closes it when hot. Mine is not working that way. It is closed cold and does not move when hot. I thought that the anti rattle spring provided the force to keep the flapper open, but that is wrong. I' going to pull the manifold off and find out why mine acts opposite. I think the thermostatic spring is in backwards.. More later. Thanks again.

I found the thermostatic spring was in backwards, and therefore the flapper was always in the horizontal, or hot position. Turned it around and verified operation with heat from a propane hand torch. Very pleased that this will work now. Haven't found an anti rattle spring yet at the hardware store that is suitable.....need one that is very weak. Ill keep looking. Sure appreciate all of the comments and help.

Jim, I got my springs for my Manifolds at Ace Hardware.

I guess mine was frozen at one time and the guy I bought the car from just took the whole flapper out because there is no flapper in my manifold. This means it is always in the open position. Can I run the car like that? What would be the harm? Would anything get ruined?

I have replaced mine with a hardware spring and it works just fine. What this does is aid in the proper vaperization of fuel during warm up. Also, it will minimize, or eliminate, the danger of crankcase dilution of oil by raw, or unvaporized fuel from entering the combustion chamber and leaking into the crankcase.. If you run you car in cold weather and it does not "warm up" due to short runs it is recommended changing of oil more often. This Exhaust Manifold Heat Control is designed to reduce the back pressure to a minimun. It results in keeping the proper temperature of incomming mixture at all times and is a factor that contributes to Chevrolet's economy.

If the flap is jammed in the vertical position, once the engine was warmed up and running, on a hot day, the exhaust gasses would be directed UP to the inlet and carburetor position and SUPER heat the inlet, resulting in possible fuel percolation, and the engine eventually stopping.

Rolls Royce call it " failure to proceed".....

I found that my flap was rusted solid and had to totally remove it and install a thin metal plate over the gasket so the exhaust gasses escaped with out venturing upwards and super heating the inlet to the carburetor. In my climate, using the car on club runs it gets a good warm up and run every time so I figured that what I did was my way forward...
Peter