W.T.B.: 1957 Buick Exhaust Manifold valve body thermostatic coil

[buick man]

My thermostatic coil broke while I was lubricating the valve body on the passenger side exhaust manifold on my stock 1957 Buick dual exhaust system. I am referring to the coiled spring that opens and shuts the butterfly valve inside the manifold where it meets the exhaust pipe.

Looked at the sites for parts ie. Car inc. Bobs, etc but could not find one.

Does anyone know where to get one or is there a confirmed substitute part out there somewhere?

Discussion: I noticed as I was using penetrating oil to free up the valve body, that the other end has a weighted pendulum that swings the valve back to a static position. Mine is very clean and free now and swings back to this static position. I suppose the spring when cold draws the butterfly valve closed and when exhaust gases heat up the manifold and spring, it tensions and opens the valve. But which position is which?

My question is if the spring is broken is the internal valve open or closed when cold. If it stays open then I could drive it that way until I find a spring but if when the spring is broken and the pendulum swings the valve back to it's static weighted position, is the valve open or closed at this point?

I suppose I could readily answer my own question if I were to take off the exhaust manifold, but do not want to do this unless absolutely necessary at this point.

Do some folks just remove this valve completely and plug up the shaft holes and go to an electric choke setup?

Any facts, input or advice on this would be most appreciated.

Thanks in advance.

David

[Guest century55]

your right about the valve being closed when cold. the spring heats up when the motor is at operating tempiture and opens the valve to let the back pressure and heat from ex. out. i didn't like the rattleing it makes so i took mine off. after this you HAVE TO use your auto chock to keep the motor runneing. i might have the one i took off, i'll look for it and let you know. danny

[1957buickjim]

David, I might have one as well on an old manifold. I will check as well and let you know. Jim.

[Spitfire8]

David: Without the spring, I believe exhaust gas pressure will probably open the butterfly when the engine is at speed; assuming the shaft is free. (Goose the throttle, and watch the shaft to see if it rotates). However idle speed may not produce enough pressure to keep the butterfly open; thus prolonged idling in this situation can promote overheating and contribute to hot-start problems.

Remember too, that these older motors had a lot of iron mass and coolant. Getting all that up to operating temperature as quickly as possible is desireable, and this was the job of the manifold heat riser.

[buick man]

Thank you for your replies. Let me know what you come up with. Yeah these engines do have a lot of iron mass to them indeed and that's a good point spitfire8.

If I leave it alone I just want to know which position the pendulum should be in for a fully open valve. I was working in this area of the car a few weeks ago and have left it for now. When I return to it, I will most likely take the header pipe off that leads to the muffler and take a peek!