I read on this forum that the Corvette control valve had a 55 pound centering spring with an "X" stamped on the cap to designate it for the Corvette. The Chevy II had a 30 pound centering spring with a "C" stamped on the cap. I have a 67 BB that needs the control valve replaced. It is my understanding that the control valve needs to have the 55 # spring. Today I checked with Lonestar Caliper Co. and they told me that they have always used the 30 # spring and did not know anything about the Corvette requiring a 55 # spring. This surprised me since they have been rebuilding this stuff for Corvetts for years. Can someone please confirm that a 55# spring is necessary and if so does anyone know of a vendor who can provide or rebuild a control valve with the 55# spring? Thanks in advance for your input.
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Re: Control Valve Centering Spring
Paul-----
As far as I know, 1963-1973 Corvettes using control valve GM #5691955 were equipped with a 55 LB. spring. These units did have a valve end cap that was marked with an "X". About 1974 the control valve changed. As far as I know, there were at least 2 changes. First, a hose guide bracket was added to the valve. Second, the spring was changed to a 40 LB. rated piece. These valves were marked with a "C" on the end cap. It's possible that this same valve was used on Chevy II's but, if so, the spring was a 40 LB, not 30 LB. Also, complete SERVICE valves with the 40 LB spring were supplied for years by GM for all 1963-82 applications. So, apparently, GM deems the valve with the 40 LB spring to be approved for all model year applications. They might even deem it to be better than the 55 LB spring.
I don't know, for sure, what spring or end cap stamping was used on Chevy II's or other applications using the same style control valve.
As far as where to obtain the 55 LB spring, if you have an original valve then you already have one. Simply rebuild or have rebuilt your valve.
Perhaps Jim Shea can provide some more information on this issue.In Appreciation of John Hinckley
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