Another heat riser question (1970). Is 720 degrees normal?

[Northcoast300h]

Hi, I did a search but can't find this specific answer. Based on pics, can anyone tell me - Is my heat riser open or closed? It won't turn and unbolting the exhaust might seem easy but moving it out of the way would be a pain in the A (no room). The flat area on the knob is pointing vertical. (up/down). Turning riser counter clockwise will open it, correct? Are there any other markings?

Since I don't drive it in winter and have an auto carb choke, I just want it open all the time. I think its partially closed since that side is running around 720F. The other side of engine is running around 650F. Heat riser might have been fully closed before I owned it because I had to weld up a nasty manifold crack (I didn't have to take it off). Thanks guys!

 

[CBODY67]

On the "old style" counterweight, it was easy to tell if it was more open or closed. On those, they usually stuck about 40-50% open, by observation.

The spring on the back, around the shaft, is a thermostatic spring to react to the ambient temp around the valve/counterweight. Plius keeping the valve closed during cooler temps.

From my experiences on our '66 Newport 383 2bbl, the valve would "stick" due to the bushings in the manifold, which the shaft slides through, were too tight. Which would restrict shaft turning over a short time of being that way. When we had the dealer replace the valve with their repair kit, even THOSE bushings were too tight, BUT after a little reaming action, everything worked freely, as it should.

When you get the manifold off, you probably will discover a retainer that slides onto the shaft to keep it in place. Remove that retainer and you should be able to drive the shaft out of the manifold, also driving ehit through the flapper valve in the manifold, which is a slip fit on the shaft (although a tight one). After that, you can clean up any corrosion on the shaft and then selectively enlarge the bushings until the shaft slips in and turns easily. Reinstalling the flapper valve is optional for you, all things considered. Then re-install the manifold with a new flange gasket.

IF you're trying to determine the valve's position, the heavy part of the counterweight should be at the bottom for the valve to be fully open, I suspect.

As for performance, I could not tell any difference with the 2bbl engine. There might have been a bit less at WOT, but there was already enough there as it was. Additionally, one OEM stated in a TSB that in the case of throttle opening percentages, by the time the throttle body's throttle plate is at 75% of "open", 90% of total air flow through the valve is already there. FWIW

Enjoy!
CBODY67

 

[Northcoast300h]

Great info CBODY67. I'll look at the round counterweight and try to determine which side is heavier. If I need to, I'm just going to keep screwing with it to get it to turn. I know it'll leak but there's enough room to weld it up, or try clamp it down. Trying to remove these old rotted bolts on the manifolds would be a disaster. I don't care about speed. I think all old muscle cars are slow compared to today's standards, but the looks, smell and even the comfort of old cars are awesome.

 

[Northcoast300h]

OK, I checked it out. Heat riser looks the same all the way around. Where is the heavy side? Other side is just the shaft and a tiny spring. I made a grind mark on the bottom of heat riser representing vertical with ground (see 3rd pic). The flat area on the shaft which is visible in the 2nd, and where I think the thermostatic coil would go, is vertical to the ground. Any help is really appreciated.

What a silly design and crappy place to put it. No stickers or anything mentioning it needs to be lubed at every oil change. I wonder how many manifolds cracked and Mopar engines died early due to the added heat and backpressure?

Thanks!

 

[HWYCRZR]

Here are some pictures from my underside. Mine is a ‘68 but the manifold is a ‘70.
When closed the weight is angled (not completely vertical. Turn it clockwise to open. The weight is now straight up and down. (Vertical when open).
On mine when closed the Chrysler emblem is towards the block. When open straight down and part number at the top is right side up.

Closed: wider gap between weight and flange

Open vertical narrow gap between weight and flange.

 

[Northcoast300h]

Wow, great pics HWYCRZR. This should be all I need. Really, yours turns clockwise as it heats up to open? Many posts say our Mopars go counter clockwise to open? Can you check on that? Thanks!

 

[HWYCRZR]

If I am standing underneath looking at the emblem it rotates clockwise to open. At least that is the direction that is fighting the spring. Here is a video of the operation.
This faces the front side of my engine. In ‘68 it looks like it was facing the rear. My manifold is a early’70’s.

 

[HWYCRZR]

Pictures from top side.

 

[Northcoast300h]

Wow HWYCRZR...You're the man! Mine is upside down from yours. Do you know why? It looks like its 180 degrees from yours, so probably in the wide open position? Seems like engine runs hotter on that side. Maybe I'm just being paranoid. Maybe I should just leave it locked up at that position? Car runs fine, just hotter on that side than drivers side under hood. I think I'll just leave it alone, or should I unbolt exhaust pipe to see and hope not to break anything? This car is like working on an old lady.

ND is awesome. Beautiful wide open state (*except in Winter and Williston, lol) I worked in every state and Canada 10-50 times, (ND about 15). Go Bisons!

 

[HWYCRZR]

Wow HWYCRZR...You're the man! Mine is upside down from yours. Do you know why? It looks like its 180 degrees from yours, so probably in the wide open position? Seems like engine runs hotter on that side. Maybe I'm just being paranoid. Maybe I should just leave it locked up at that position? Car runs fine, just hotter on that side than drivers side under hood. I think I'll just leave it alone, or should I unbolt exhaust pipe to see and hope not to break anything? This car is like working on an old lady.

ND is awesome. Beautiful wide open state (*except in Winter and Williston, lol) I worked in every state and Canada 10-50 times, (ND about 15). Go Bisons!

View attachment 397697 View attachment 397698 View attachment 397699

You know it definitely is possible to put it in 180 degrees differently as it really is just a quarter turn valve. If yours is 180 off, I would say that it is in the mostly open position. If you can check the temperature just below the flanges on each side you should be able to tell. If it is stuck closed, the passenger side, after the valve should be cooler than the drivers side. If it is open. They should be close in temperature below the flange on each side.
Some of your perception on top could be the alternator and or A/C could be blocking some air flow from that side. Also your heater hoses go that way as well creating surface heat.

Go Bison!

 

[1970FuryConv]

Given that your pipe flange bolts look good. I'd spray the manifold mounting bolts with WD40 or Liquid Wrench for three days and then take manifold off and see what you've got. I don't see how one side can be 70° hotter if it's not partly closed. I agree with cbody67 on removing it and deciding whether you want to keep the internal plate and rod. It may be simpler to remove both and have a shop weld up both holes.
My 1969 HP manifold, right side, some one had already closed both holes
Before, as received from ebay seller

After wire wheel cleanup and POR15 Exh Manifold Paint

 

[oldkimmer]

Have u considered that 1 cylinder may be leaner than the others? Years ago when I had 1 stick closed the temp difference was more than 300 degree’s. Kim

 

[fury fan]

Drilling/tapping them for pipe plugs, or installing a 3/8-16 bolt with copper washers and a distorted-thread locknut is always my preference over welding them closed. Welding cast is a lost art and I don't want to risk introducing a crack.