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curt
09-26-2005, 08:39 PM
How do you know if the heat riser valve is working? Mine moves free. BUT. The fellow I had put the crossover pipe and Y pipe on said it was not open when it came in to the shop. HE felt it should have been open to some degree.. Could it be on upside down? But how do I check if it is open? VAcuum test? What?

N8N
09-26-2005, 08:42 PM
with the engine cold, grab the weight and see if it moves free. If it doesn't, or if it moves *completely* free (i.e. doesn't snap shut when you let it go) then you have a problem.

nate

--
55 Commander Starlight
62 Daytona hardtop
http://home.comcast.net/~njnagel

curt
09-26-2005, 09:03 PM
Sounds like an easy test. The car is hot now, I know it moves freely cold, I do not know if it springs back when opened by hand with a cold engine. Can one pruchase the the valve, or should one wire it open? I do not plan winter driving.

N8N
09-26-2005, 10:30 PM
yes and yes. I believe a '67 (?) Cadillac valve is a perfect functional replacement.

nate

--
55 Commander Starlight
62 Daytona hardtop
http://home.comcast.net/~njnagel

GTtim
09-26-2005, 11:26 PM
Here is another wrinkle in the heat riser valve issue. I thought mine was operating just like it should, it was always nice and free. When I took the exhaust pipe off the header I found out that the flapper inside the pipe was loose on the shaft. It was screwed around so that when the car was cold it was not completely shut and when it was hot it was past full open and starting to close again. So, I have to say take the pipe off and look if you want to be certain.
Tim K.

curt
09-27-2005, 08:05 AM
It moves as N8N says it should. If someone instaled the heat riser valve upside down would it function free and snap closed when cold BUT fail to operate properly or is the 'valve-plate' not sensitive to orientation?

gordr
09-27-2005, 09:10 AM
Curt, the heat riser valve IS position-sensitive. There is, or should be, a counterweight on the outboard end of the valve shaft, shaped like a small segment of a circle. The bimetal spring acts to close the valve against the force of the counterweight when cold; as the engine warms up, the bimetal spring relaxes, and the counterweight ensures that the valve opens promptly. If the counterweight isn't there, the valve may not work at all.

I agree with GTtim that the valve butterfly can work loose on the shaft. If the valve were installed upside-down, the counterweight would act to keep it closed, and I doubt the bimetal spring could overcome its weight. I think the valves had "TOP" molded into the top surface of the body casting. Of course, you can't see that when its installed.:(

Gord Richmond, within Weasel range of the Alberta Badlands

52hawk
09-27-2005, 09:38 AM
quote:Originally posted by N8N

yes and yes. I believe a '67 (?) Cadillac valve is a perfect functional replacement.

nate
--
55 Commander Starlight
62 Daytona hardtop
http://home.comcast.net/~njnagel

I put that caddy heat riser on my 289.The flap was too big,so I grinded some metal off the edge.Now it makes a stupid whistle sound,and has to come back apart. Just one more little detail to slow the finishing of the car.

Home of the Almostahawk

curt
09-27-2005, 08:52 PM
Gordor or anyone: The bimetal spring when heated by torch moves the counter weight on the heat riser valve. It looks like the counter weight works aginst the springs movement as the spring is heated. The spring moves the counter weight as it heats with the tourch. Just runing the car I do not see counter weight movement. Any coments about the above valve and if the valve is working proper or not is apreciated.

GTtim
09-27-2005, 09:16 PM
The hidden flapper valve in the pipe is made such that the rushing exhaust gases tend to force the valve open. If the car is warmed up and if you accelerate the engine you should be able to see the valve open. When the engine comes back to idle it will probably close. If the thing is installed backwards this action won't happen because the force of the exhaust will tend to hold the valve closed.
Good luck,
Tim K.

gordr
09-27-2005, 09:32 PM
Curt,

I second Tim K. on this.

Try this: with the engine and bimetal spring cold, the counterweight will be at its rest position, against a stop pin, as a matter of fact. The flapper valve should be closed, if it hasn't slipped on the shaft.

Now which way does the counterweight have freedom to move? The heavy side should be able to go down, against the spring tension. If it wants to go UP, the heat riser is in upside-down. If the only constraint against movement of the counterweight is the bimetal spring, in either direction, then the stop pin is missing, and the valve needs to be replaced or fixed.

I'm not at home, or I'd go outside and look at a Stude or two and tell you normal rotation direction of a good heat riser.:(

Gord Richmond, within Weasel range of the Alberta Badlands

curt
09-27-2005, 09:35 PM
I will try that tomorrow night, sounds so logical, thanks. I had a Kaiser with the smoothest heat riser valve I have ever put my hands on. The maniflod needed replacing, when I got the manifold off all the valve consisted of was a naked shaft, the butterfly ( or what ever you call it) was gone. No functional heat riser but the shaft turned and worked fine.

curt
09-27-2005, 09:45 PM
Gorder, it looks like the main movement of the counter weight is upward. The big thick part of the counter weight is almost down at room temperature. As I heat the spring with a torch the spring tightens and moves the valve.. Engine heat does not seam to be enough to move the weight, a hot torch flame moves the counter weight.I will try GTtim's test and I bet the faster RPM will not move the weight. If I had to say tonight I would say this valve is upside, darn it. [xx(]