The Stovebolt Site Forums The Shop Area Engine Shop Heat Riser Valve Spring

Hi everyone:

Would someone please explain how to install the heat riser spring? I tried for about an hour every which way from Sunday, and I still got it wrong. Thanks.

Here are 2 views: http://s1154.photobucket.com/user/JonGoodman/media/MVC-061F.jpg.html?filters[user]=125067356&filters[recent]=1&sort=1&o=0

http://s1154.photobucket.com/user/JonGoodman/media/MVC-062F.jpg.html?filters[user]=125067356&filters[recent]=1&sort=1&o=0

Hope this helps.
Jon

http://s1154.photobucket.com/user/JonGoodman/media/MVC-061F.jpg.html?sort=3&o=0

http://s1154.photobucket.com/user/JonGoodman/media/MVC-061F.jpg.html?sort=3&o=1

Maybe these will work...
Jon

Thanks. Mine looks exactly like that, but when the truck heats up the valve doesn't open, it seals shut. I think maybe the spring is turning the wrong way?

The valve moves, I freed it up before installing the manifold.

If the valve shuts when the spring heats up, the spring is backwards. When the spring heats, it should relax allowing the valve to be directed by exhaust gas flow (which should force it to send the exhaust out and not over the carb base)
Jon

I had the same problem, I even bought two springs, I eventually just left it with no spring, it had worked just fine with no spring for 25 years that I know of. Well it may have had a spring for some of that time, but at some point it broke, and since when and if it fell off, I never noticed any difference whatsoever. I just left it that way...now I have an aluminum intake with water heat, so the whole point is, well pointless.

When the spring heats up the flapper moves to the heat off position




...QuickTime video...

http://chevy.oldcarmanualproject.com/shop/1948_51truck/51ctsm0604.htm From the picture you can see that the shaft rotates CCW to open and CW to close as viewed from the engine front. Using that you can tell how to orientate the spring. Heat it over the stove to see how it expands and go from there. I assume you have a counter weight on the front of the shaft

I always noticed mine will open and close with the reving of the engine. Whether the spring is weak or not.

John

After heating it in a pot of water I see that the spring "shrinks" when heated. This was throwing me off because it seems like it should expand.

So the spring was on right the first time, funny that the valve wasn't moving into the "heat off" position. Maybe the engine wasn't hot enough, or maybe because the exhaust isn't installed yet.

Thanks.

The heat control valve thermostat is really not a spring. It's a
bimetal strip and simply placing it on the manifold isn't
enough. It needs to be adjusted by either coiling it tighter or
uncoiling it. This may take a few tries to get it set
correctly.

Denny Graham
Sandwich, IL

The tension of the spring is important. Here is the process in the 1955 Shop Manual.

I realize now that the the first installation was waaay too tight, even though it was only about 1/2 turn as per the instruction manual.

After adjusting the tension the bi-metal spring went on quite a bit looser, so hopefully it will now work.

Thing that you gotta realize is these aren't the original
thermostats, they are made from whatever bi-metal strips
someone was able to find so they aren't gonna just plug in
like the original from GM. That's why I said you're gonna need
to play with it to find the sweet spot.
Just try finding a source for bi-metal strip or sheet and you
will see why it's not the same as the original part.

Denny G

How are you testing it?

You mentioned earlier that your exhaust is not installed

I started the engine and watched it run at idle for several minutes. It was hot, the temp gauge showed 180 degrees, but the valve didn't budge.

Exhaust pipes are not yet installed, but the manifold is. I wouldn't think having the pipes on or not should make a difference to how the valve operates.

Wednesday the truck goes to the exhaust shop about three miles away. So that should be a good test to see if the valve moves to the "heat-off" position.

Like mentioned earlier

A little goose from the accelerator will help move the weight.

Sure enough the valve moves into off with a little throttle. So I guess it works!