C2 - Heat Riser Valve

[Stephen P.]

How much movement is there in in the heat riser valve? The counterweight on mine sits horizontal (when cold). I can only push it down about a half an inch. It doesn't go vertical. I saw in the archives that it should have 90 degrees of movement. Is that accurate?

[Wayne P.]

Re: C2 - Heat Riser Valve

yes it should move 90' so that it is now vertical an offers minimum resistance.

[Mike M.]

Re: C2 - Heat Riser Valve

Take the heat riser off the car and using krol or wd-40 or some such lubricant,gently loosen up the pivot points with the heat riser in a vice and you manualy working the flap valve back and forth till you have about 90 degrees of movement. then go for it. good luck, mike

[Jack Layton]

Re: C2 - Heat Riser Valve

Sometimes a heat riser valve which is "freely" moving on the work bench will become "cocked" or twisted upon installation and then "bind" so that it will no longer open 90 degrees after installation. The cure is to be sure that the valve is properly aligned as you tighten the nuts. BTW : Brass nuts if it is a non-judged car.

[Stephen P.]

Re: C2 - Heat Riser Valve

Thanks for the advice. Since I've got to take it off anyway, I've ordered one of the spacer plates and plan to remove the heat riser valve since I don't need it for the carb I'm running now.

[Joe L.]

Re: C2 - Heat Riser Valve

Steve----

From a functional standpoint, you're better off in most situations without the valve or with the valve wired open. Even for judging, I'd go with a valve with the butterfly plate removed. These valves are the cause of the "early demise" of right side mufflers on C2 and C3 Corvettes.

[Chuck Swenson]

Re: C2 - Heat Riser Valve

I've seen many rams horns with brass nuts. They are not correct for judging? If not, should they be locking nuts or lock washers w/ nuts? Why would brass nuts be better than stainless steel?

Thanks, Chuck

[Jack Layton]

Re: C2 - Heat Riser Valve

Brass nuts will not rust tight to the exhaust manifold studs. They are easy to remove with out damaging the threads. The factory used cheap regular steel nuts. That is why a lot of exhaust manifold studs are broken.

[Chuck Swenson]

Re: C2 - Heat Riser Valve

Thanks Jack! Hopefully the stainless steel w/ nuts will be fine. It will at least look original.