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My exhaust manifold is missing the exhaust manifold riser weight and did not permit the flapper to open resulting in the insulator spacer that Max Merritt sells between the carburetor to intake manifold to melt, the spring holds the flapper in the closed position and when the spring expands the weight on opposite end of the shaft provides enough weight to open the flapper all the way, so what is my question? I just removed the spring and turned the shaft in the rotation that moves the shaft to the open position which is clockwise on the weighted end of the shaft, my question is when in this position is the flapper in the fully open position? the only way to see the flapper is to remove the pipe or entire intake manifold and I really do not want to do that.

The function is that when cold, the coiled bimetallic spring provides enough tension to hold the counterweight UP and in this position the valve is closed. As the spring warms up it relaxes (uncoils) from the heat, allowing the counterweight to drop down and thus opening the valve.

Yes, I feel better now I know that it is locked in the open position. Thank you

Maybe Dave or someone can verify if these images are correct for operation of the heat control valve.

Also a service letter reprint on the manifold heat control valve/heat riser says: The valve sticking in the open position will cause slow engine warm up, excessive spitting and sluggish engine operation when cold. A valve sticking in the closed position will cause overheating, loss of power, hard starting when hot, and may also cause warped or cracked manifolds. Sticking in either position will adversely affect fuel economy.

EDIT I keep looking at this and thinking I have my spring on backwards or something. The manifolds are being planed, but before we put them on the block I'd like to be sure we have this set up correctly.

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