383 broken manifold heat control valve

[Gonzo]

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?

 

[CBODY67]

From our experiences on similar vehicles, the valves usually stick 1/2 open, which is where they can stay indefinitely and cause no problems. If the valve now rotates freely, you probably need a new thermostatic spring, which is on the engine side of the exhaust manifold, unseen usually.

There needs to be some exhaust heat in the intake manifold for the correct functioning of the divorced automatic choke. That heat initially comes from the exhaust crossover in the center of the intake manifold. IF you have a carb with an electric choke, no need for that heat, as the electricity in the choke heater coil supplies it.

At the very least, you need a new thermostat, but you have to get the complete heat riser rebuild kit to get it. Some are available online, usually, or from some Mopar-related vendors. Otherwise, the exhaust pulses can rotate the valve at will and cause unusual clangings and such, possibly.

Might also need to prepare to remove the exhaust manifold for inspection to see what is really going on. Taking it off sounds worse than it really might be.

Just some thoughts,
CBODY67

 

[Gonzo]

I did more searching and found another thread which said the "hook" should rest against a pin to be in the full open position, which it does, and was before I tried to make things better. It rotates so freely now I am concerned about never knowing what position it's in while driving. Could this be a bailing wire job?

 

[CBODY67]

Good heavens!!! Bailing wire is for Fords. Stainless steel safety wire is for Chryslers.

 

[Ross Wooldridge]

Complete kits or parts available here:

Dynamic Renovation - 1966-69 Big Block 440 383 Heat Riser Kit

 

[CBODY67]

Complete kits or parts available here:

Dynamic Renovation - 1966-69 Big Block 440 383 Heat Riser Kit

Just be sure to check the shaft for clearance. The Chrysler kits we got back in the 1970s had bushings that, when installed, caused the shaft to bind . . . until they were reamed for size, then the shaft fit and rotates normally.

 

['66 Fury I]

After several unsuccessful attempts to repair the hear riser valve on my 318, I gave up and removed it. I plugged the shaft holes by threading them (5/16 NC if I remember) and installing short bolts as plugs. I did this over 5 years ago and am pleased with the results. The choke for the Thermoquad works well and there are no problems noted. I suspect, however, that warm-up and carb icing could be troublesome if I were using the car in cold damp weather. Don't take this as any more than my experience FWIW. Lindsay

 

[stubs300]

I did more searching and found another thread which said the "hook" should rest against a pin to be in the full open position, which it does, and was before I tried to make things better. It rotates so freely now I am concerned about never knowing what position it's in while driving. Could this be a bailing wire job?

Yes, you can just safety wire it to the open position and then forget about it. No need to change or fix it unless you want to. Good Luck

 

[Gonzo]

Thanks for that. It has been stuck open since I got the car, she started well in the winter cold, so I'm not sure how life would be better if it was working as it should.

 

[Grannys67]

Mine's also been stuck solid in the open position forever; never had a problem with starts in colder weather, so I just left it.

 

[MoparMike]

When I rebuilt my motor and put the 69 HP manifolds on, I removed the heat riser and welded the holes shut. I have never had a problem.

 

[Big_John]

The internal flapper on mine went MIA long before I bought the car.

Given the gas we deal with now, I would not make it operational. My cross over is also blocked and I run an aftermarket electric choke. No problems.

 

[Gonzo]

I appreciate you guys giving me feedback. I too have an electric choke and found no trouble starting in cold weather( sometimes hot starts can be difficult, though). I'm just going leave the valve jammed wide open.

 

[Elvis Lean Burn HP]

For Clarification I would like some input related to the valve being in the (open) position. My 77 Newport valve moves freely and I would like to (wire) it in the open positions. When I rotate it clockwise and it stops that is considered (open)? Any tips would be appreciated

 

[Gonzo]

My experience with exactly this problem is worth telling. What I had read about the "open postion" lead me to believe that when the valve was rotated to where 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.
Now it's back to finding oil leaks.

 

[Elvis Lean Burn HP]

My experience with exactly this problem is worth telling. What I had read about the "open postion" lead me to believe that when the valve was rotated to where 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.
Now it's back to finding oil leaks.

Gonzo thanks for the reply

For clarification

Counter Clockwise is (Closed)?

Clockwise is (Open)?

 

[Ross Wooldridge]

The counterwright has to be down for the valve to be open. It's held closed (for cold weather warmup) by a heat senstive bimetallic spring. Once the spring warms up it relaxes, and the counterweight drops as gravity takes over, and th valve opens.

Whichever way it rotates, as long as the counterweight is at the bottom of the rotation, you're good.

FWIW, I'm a nerd, and therefore I like mine to work, so I fix them.
Parts are available:

Dynamic Renovation - 1966-69 Big Block 440 383 Heat Riser Kit

 

[Elvis Lean Burn HP]

The counterwright has to be down for the valve to be open. It's held closed (for cold weather warmup) by a heat senstive bimetallic spring. Once the spring warms up it relaxes, and the counterweight drops as gravity takes over, and th valve opens.

Whichever way it rotates, as long as the counterweight is at the bottom of the rotation, you're good.

FWIW, I'm a nerd, and therefore I like mine to work, so I fix them.
Parts are available:

Dynamic Renovation - 1966-69 Big Block 440 383 Heat Riser Kit

Thank you for the response. I have a 1977 400. Does not seem to be a counterweight. Basically its 360• round.

I wired it tonight clock wise I’ll give it a test drive tomorrow

 

[Ross Wooldridge]

In that 360 degree circle will be a counterweight.

The other option is to wire it up one way, run the car for only a minute or two and see if the LS exhaust pipe gets warm down at where it meets with the other exhaust pipe. If it does, you've wired it open. If not, you've wired it clised.

If you have dual exhaust, do the same thing - see which position of the counterweight shuts the left side tail pipe off...

 

[Elvis Lean Burn HP]

In that 360 degree circle will be a counterweight.

The other option is to wire it up one way, run the car for only a minute or two and see if the LS exhaust pipe gets warm down at where it meets with the other exhaust pipe. If it does, you've wired it open. If not, you've wired it clised.

If you have dual exhaust, do the same thing - see which position of the counterweight shuts the left side tail pipe off...

Superb. Single exhaust. Y pipe. Ill post my findings tomorrow