1966 Newport 383 2-Barrel – Exhaust Manifold Heat Riser Question

[IHChris]

I recently acquired a 1966 Newport with the stock 383 2-barrel engine.

I noticed that the spring and counterweight are missing on the exhaust manifold heat riser mechanism. Does anyone know which way to turn it so that it stays open?

I found this thread, but there was never a definitive answer:

G

Thread '383 broken manifold heat control valve'

Apr 11, 2023

So, today I checked the manifold heat control valve on Rosie, a '67 383 Fury. It was stuck but seems broken because it when I freed it with penetrating oil it rotates but has no spring action to return it to open. Now I am concerned that besides not working, I have to assume it was stuck in the open position.
I got out the shop manual, it indicates full clockwise would be the run position. But now that it's moving freely will it vibrate to close position?
What signs or symptoms would I be looking for if it was stuck closed?
Also, do I really need this feature?

• Gonzo
• Replies: 34
• Forum: Early C Bodies - The Slab Side Years

Chris

 

[SIPLOWGUY]

It says full clockwise.

 

[IHChris]

The person who started the thread also replied later, saying:

"My experience with exactly this problem is worth telling. What I had read about the 'open position' led me to believe that when the valve was rotated to where the notched plate stops at the pin (I think it was clockwise) that it was open. I made it stay that way and put down a couple of hundred miles until a manifold leak on the same side required that I replace the gasket. With the manifold off it was clear that I had the thing in the closed position. So, correcting that goof had stupendous results. The car seemed to gain at least 20% more power and run smoother than ever.

So it sounds like it’s not actually clockwise, but he doesn’t remember for sure. Someone tried to get clarification, but he never responded.

Chris

 

[SIPLOWGUY]

Best way to be sure is to drop the engine pipe.

 

[IHChris]

Best way to be sure is to drop the engine pipe.

Yeah, I know. I was hoping not to have to do that, but it sounds like I may have to.

Chris

 

[Ross Wooldridge]

The weight is to be low when the valve inside is open. The thermo-spring pulls the weight up when it's cold, and relaxes when warm, so the weight drops (rotates actually, due to gravity), and in the process, the valve is opened inside the manifold.

New heat riser parts are available here: Dynamic Renovation - 1966-69 Big Block 440 383 Heat Riser Kit