Heat riser valve -

[patinated_imperial]

It turns out the heat riser valve in my '66 Imperial is moving freely.

I rotated it "by mistake" when changing spark plugs.

Actually I would have preferred if it where stuck open (I only drive in the summer). Now, I have doubts in which position to fixate it, to make sure it is open.

The challenge is, the torsion spring is not operating and I have plenty of other things to work on. I would like to avoid taking off the pipe and/or manifold at this point.

I am correct, that this is the closed position (rotated counter clockwise)?:

And this is the open position (rotated ~90° clockwise)?:

The valve would like to rest in this position, but I am wondering if it rotated so much, that it is actually starting to close?:

 

[Ross Wooldridge]

Does your car have dual exhaust? If so, the easiest way to figure that out is to run the engine, and see which way makes the passenger side tail pipe not emit any real exhaust pressure. That would indicate CLOSED position.

Be that as it may - when the thermo spring is cold, the counterweight will be in the up position, as it contracts it closed. When hot, the spring loses its tension (by design), and the counterweight will drop and force the valve to sit in the open position.

By the way, new parts are available to repair your heat riser from this place: Dynamic Renovation - 1966-69 Big Block 440 383 Heat Riser Kit

 

[thethee]

I've heard about Dynamic Renovation before as I also have a freely moving heat riser valve, but I'm having trouble reaching the website it's just not loading. Is it just me or do more people experience this?

 

[patinated_imperial]

Does your car have dual exhaust? If so, the easiest way to figure that out is to run the engine, and see which way makes the passenger side tail pipe not emit any real exhaust pressure. That would indicate CLOSED position.

Be that as it may - when the thermo spring is cold, the counterweight will be in the up position, as it contracts it closed. When hot, the spring loses its tension (by design), and the counterweight will drop and force the valve to sit in the open position.

By the way, new parts are available to repair your heat riser from this place: Dynamic Renovation - 1966-69 Big Block 440 383 Heat Riser Kit

Unfortunately - in this case - it has a single exhaust.

So my assumption (based on the description in the FSM) sounds correct. Still wondering if it is rotated too much in the third picture.

Thanks for the link!

 

[Ross Wooldridge]

@thethee - The website immediately loaded for me... not sure what your issue could be - likely server based.
@patinated_imperial - the only way to really see would be to drop the head pipe and have a look. There should be stop pins that prevent movement of the valve beyond both closed and fully open positions.

 

[patinated_imperial]

@thethee - The website immediately loaded for me... not sure what your issue could be - likely server based.
@patinated_imperial - the only way to really see would be to drop the head pipe and have a look. There should be stop pins that prevent movement of the valve beyond both closed and fully open positions.

The dynamic renovation site loads fine for me too and I am on the same side of the pond as thethee...

Yes, maybe I should surrender to dropping the pipe . When I have a gasket on hand that is... I might try and tape a thermocouple to each down pipe, to see if they heat up at the same rate.
Good point on the pin. On the Imperial, I think it is just the one pin you can spot in the pictures on which the counterweight catches on.

 

[Big_John]

Start the car, rev the engine and watch which way it turns. Exhaust pressure will push it open.

 

[patinated_imperial]

Start the car, rev the engine and watch which way it turns. Exhaust pressure will push it open.

If the valve "disc" is hinged in the center, I am not sure it will.
But I will try it and report back here!

 

[Ross Wooldridge]

They're not typically hinged in the middle, particularly to avoid them spinning... they're offset a little, and can only open so much. But John's advice stands up regardless as a way to see which way is open.

 

[Jimda]

Mine is completely missing the stud spins freely but it does make a rattle id like to lose. But no leak

 

[CBODY67]

That rattle you might not like is your friend telling you that everything is still free and good.

IF youi might find a picture of the rh exhaust manifold with your configuration of heat riser valve in the picture, it will probably be in the closed position. On our '66 Newport, it has a later-style valve with a hook on the end of the counterweight, which is the open-limiter for full open, ccw rotation. If that travel limiter stud is removed or deformed, it probably can be easily removed and replaced, but with the manifold removed, I suspect. Probably just a solid dowel of a particular size and length?

Seems like that under the earlier-style counterweight, there is a soft travel limiter under the sheet metal? Again, probably illustrations in either the FSM or Chryselr Parts Manual, I suspect.

ONE thing I discovered is that at idle, the exhaust flow past the heat riser flapper is anything but smooth. Positive and negative pressure pulses which will went to open and close the valve, by observation. Unrestrained, they can make one heck of a racket.

Just some thoughts,
CBODY67

 

[Jimda]

I guess the question then is how do I tell its open so I can leave it open and stop the rattle

 

[CBODY67]

Possibly the position of the counterweight of when the engine is stone cold and when it's up to operating temp? With the engine stopped, of course. Other than the noted pictures in the FSM, which would be for a stopped cold engine, usually.

Or get the gaskets and remove the y-pipe for inspection of the flapper position.

 

[patinated_imperial]

I found this video on youtube, where they show the operation and positions of the valve very nicely from 2:45.
The valve is identical to the one on my Imperial, and the positions and rotational direction is in accordance with what both Ross and CBODY67 wrote above.

CBODY67; you are right, there is a sort of fibre glass cloth soft limiter under the sheet metal counterweight.

I changed my mind after I discovered the only thing wrong with my valve is a broken torsional spring. Going to leave it open, but free and replace the spring at some point. Does anybody know what the contents of that special mopar heater valve lubrication is? Is it just a fancy name for a general penetrant?

 

[patinated_imperial]

If the valve "disc" is hinged in the center, I am not sure it will.
But I will try it and report back here!

@Big_John you were right. Even at idle, it is pushed open by the exhaust pressure.