C1 Heat Riser Valve Flutter

[Dave H.]

The spring on my heat riser appears to be somewhat weak. The heat riser valve opens fully as it should. However, at full open when warmed up there is no spring tension so the valve can be partially pulled back by hand. I have wired it fully open to be sure.

The question: Will a valve such as this tend to flutter under various pressure conditions, or will it be stable in the fully open condition? As the heat riser valve is designed with a longer tail, I would assume that higher pressure on the tail will tend to hold the valve fully open (assuming no spring tension). Or will there always be some flutter (leading to reduced flow through the RH exhaust)?

Dave
NCRS 42719

[Wayne K.]

Re: C1 Heat Riser Valve Flutter

Dave,

I don't know the year/model of your car but I can tell you how the heat riser on my 67 L-79 functions. As the engine warms up the spring begins to open the valve until it is pretty much fully opened even at idle. As the rpm's increase even if it isn't fully opened the exhaust pressure forces it open. Mine doesn't flutter in any position.

Wayne