Heat Riser Valve

[Brad H.]

Just completed install on correct motor on my 58, Heat riser valve on exhaust manifold which is new from CC did not budge on approx. 1/2 hour of break in, second running the next day seemed to be dropping some when hot, will the spring start to work correctly after a few more warm ups or is it a bad piece, CC said send it back and get new one, are there known problems with the new ones or what? Thanks again Brad.

[Joe L.]

Re: Heat Riser Valve

Just completed install on correct motor on my 58, Heat riser valve on exhaust manifold which is new from CC did not budge on approx. 1/2 hour of break in, second running the next day seemed to be dropping some when hot, will the spring start to work correctly after a few more warm ups or is it a bad piece, CC said send it back and get new one, are there known problems with the new ones or what? Thanks again Brad.

Brad-----


I don't know exactly what you mean by "didn't budge"? If you mean that the valve did not fully open AT IDLE after 30 minutes of running, that's no problem. I don't think that I've ever seen one that would be fully open at idle, even when warmed up. However, it should open fully when the throttle is opened ever-so-slightly.

In any event, the valve should operate FREELY by hand. If it doesn't, it's no good. Also, there is no "break in" period on the valve. It should operate properly from the "get go".

[Jerry C.]

Re: Heat Riser Valve

I have never had a new heat riser that did not need some grinding on the inside. They seem OK but when you tighten the exhaust up they seize up. Can you move the weight by hand?

[Brad H.]

Re: Heat Riser Valve

Jerry, Yes the valve works fine by hand but did not see any movement in the breakin period, but then started to funtion a little second running (trn minutes, a lot more paint burn off on that manifold vs driver side, is that normal and will run motor again this morning and check again. Thanks, Brad

[Brad H.]

Re: Heat Riser Valve

Joe, valve did not move during break in period (Higher RPM) but started a little movement second running, did not look to see if it would move when giving more gas, but yes the valve moves freely by hand, does amount of paint burn off on that manifold vs. other side tell anything or is that normal? I will run motor again this morn. and see if their is any more valve movement. Anybody else had this and if so jump in If you would. Thanks Joe if you have more send again, Brad

[Stuart F.]

Re: Heat Riser Valve

Which way does the valve move freely by hand? down or up?

Dumb question, but couldn't think of any other.

Stu Fox

[Brad H.]

Re: Heat Riser Valve

Stu, down is the way, and am I correct by everyone's advice that when gas is applied then valve moves further down with the more gas that is applied, that is the way it is now working so am I safe to say it is working correctly? Thanks Brad.

[Stuart F.]

Re: Heat Riser Valve

Brad;

Seems right. If you don't notice any binding and it has spring tension, I'd say you're good to go. Now, the next thing you do is wire it open for use like the rest of us do, right? Unwire it for show - depending on the ambient conditions where you live of course.

Stu Fox

[Dennis C.]

Heat Riser Valve

Yeah, what he said...

[Ken A.]

Re: Heat Riser Valve

Just completed install on correct motor on my 58, Heat riser valve on exhaust manifold which is new from CC did not budge on approx. 1/2 hour of break in, second running the next day seemed to be dropping some when hot, will the spring start to work correctly after a few more warm ups or is it a bad piece, CC said send it back and get new one, are there known problems with the new ones or what? Thanks again Brad.

Cut/break off the flapper blade & tack weld the pin on the inside. Then you don't have to worry about it.

[Brad H.]

Re: Heat Riser Valve

Ok now too many ideas. How is this valve actually suppose to work correctly? Seems when you firsty start car there is no movement to let excessive heat out so that manifold gets overly hot, and you also don't feel equal force out the tail pipes, as it heats up as you use throttle then you get you're movement with more and more throttle, what have I missed? Thank you all Brad.

[Joe L.]

Re: Heat Riser Valve

Ok now too many ideas. How is this valve actually suppose to work correctly? Seems when you firsty start car there is no movement to let excessive heat out so that manifold gets overly hot, and you also don't feel equal force out the tail pipes, as it heats up as you use throttle then you get you're movement with more and more throttle, what have I missed? Thank you all Brad.

Brad----


The purpose of the valve is to remain more-or-less closed at idle in cold start. This directs the exhaust gas from the right side bank through the intake manifold cross-over. In doing so, it rapidly "pre-heats" the manifold and carburetor in order to improve cold performance. For 1966+ applications, the exhaust heat is also necessary for the divorced style choke operation.

I've never noted that the "thermostatic" control of the valve resulted in the valve being fully open AT IDLE once the engine heats up, although it is usually open a little more than at initial start-up. So, at hot idle, the valve may still appear to be mostly closed but whatever amount it is open may be enough to pass the exhaust gases generated at idle in the right side bank. In any event, any significant exhaust pressure, either at initial start-up or later, will open the valve. Significant exhaust pressure is created whenever the engine speed increases much beyond idle.

[Brad H.]

Re: Heat Riser Valve

Joe, My car is 58 230 no crossover, does this change anything, and what about taking the flapper out completly like someone else noted? Thanks Brad.

[Mike M.]

Re: Heat Riser Valve

Welding the shaft would be an issue if you plan to have the car judged.
The Mechanical Judges will check for proper movement of the "Flapper".
HaND

[Roy B.]

Re: Heat Riser Valve

The heat riser is closed when cold then after the engine reaches it normal temp. It opens , (not a little or half open ) but wide open even when your at ideal. If it doesn't work as stated you have a defected spring or carbon build up.

This is my 55 original one , if you get a raddleing sound coming from it there was a after market anti-raddle item you could buy to stop the noise as seen here.
The spring was calibrated to your year vett as was the Carb choke spring was!