Re: IML: Heat riser rotation?
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Re: IML: Heat riser rotation?

Looks kind of like the coil in a HVAC thermostat, no?

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The unknowable promoted to the irrefutable.  Doubt in exile.  The
child's comfort.  The fanatic's trigger."

-- Brooke McEldowney
----- Original Message ----- From: "Roger Casagrande" <rdc2382@xxxxxxxxxxx> 
To: <mailing-list@xxxxxxxxxxxxxxxx>
Sent: Saturday, August 18, 2007 3:51 AM
Subject: Re: IML: Heat riser rotation?
I always thought it was a bi-metallic spring. It's long so that the temperature change will cause a curve great enough to rotate the valve. If anyone is in the mood, remove the spring and heat it separately. If it is bi-metallic, the spring will unwind just due to the temperature change alone. 

Roger
----- Original Message ----- From: "Bob Merritt" <bob@xxxxxxxxxxxxx> 
To: <mailing-list@xxxxxxxxxxxxxxxx>
Sent: Friday, August 17, 2007 2:07 PM
Subject: Re: IML: Heat riser rotation?



Dave is seldom wrong but I disagree with "is not a thermal spring".


From page 11-5 and 11-6 of the 1962 service manual:
"When a cold engine is started the thermostatic coil exerts enough tension to keep the valve closed. This exhaust gases from the right exhaust manifold pass through the exhaust crossover branch in the intake manifold and into the left exhaust manifold. 

When the spring heats up, it loses tension and the valve opens."
Also, same page of the service manual shows the valve is open when rotated clockwise, as others have previously replied correctly. 

Bob Merritt
----- Original Message ----- From: <sosmi@xxxxxxxxxxx> 
To: <mailing-list@xxxxxxxxxxxxxxxx>
Sent: Friday, August 17, 2007 1:13 PM
Subject: Re: IML: Heat riser rotation?
The clock spring on the riser valve is not a thermal spring. Opening and closing, is a function of exhaust gas flow(volume). When closed, all exhaust gas runs through the passage under the carb, this pre-heats the mixture for better cold weather warm-up.However if the valve is stuck shut ALL exhaust from the right bank, will pass through the manifold with less than a one square inch of passage.This only leads to poor performance, and lean carb conditions. There was also a small coil spring, for anti-rattle at low speed, or idle.Ya'll have a nice day, Dave.
-------------- Original message -------------- From: David Wilker <wilkerbeast01@xxxxxxxxxxx>
You could try finding another car with a working valve, and try it. See which way the valve opens. The spring will expand when it gets hot, so my guess would "against" the spring pressure. Maybe try moving it when the engine is running and seeing which way makes the engine run best?Isn't there a cross-over passage through the intake manifold to allow that side of the exhoust to go out the 
other manifold? I think it was to heat the intake up on cold starts.
--


David C. Wilker Jr.
USAF (RET)

---- randalpark@xxxxxxx wrote:
I have seen the counter weight slip on these, particularly between '64
and '66. The only way to determine with certainty that the valve is
open is to remove the exhaust pipe and look. The idea of comparing the
amount of exhaust coming from the right side vs. the left side is a
good one, but most Imperials built since 1962 have a single exhaust
pipe, rendering this test useless.

If the valve is stuck closed the car will over heat. If the valve isn't
stuck, then it will always open when the engine is "reved". The counter
weight isn't strong enough to keep it closed. If it is moving, it is
working fine. If it isn't moving, then you should be concerned.

Paul W.
-----Original Message----- From: nicholasadamo@xxxxxxx 
To: mailing-list@xxxxxxxxxxxxxxxx
Sent: Thu, 16 Aug 2007 5:38 pm
Subject: Re: IML: Heat riser rotation?



So Dave, I've wondered about this too. If the valve is open (engine
warm position), it is rotated all the way clockwise??? The cold
position would be all the way counter-clockwise or too the left? I am
correct??
-----Original Message----- From: sosmi@xxxxxxxxxxx 
To: mailing-list@xxxxxxxxxxxxxxxx
Sent: Thu, 16 Aug 2007 4:52 pm
Subject: Re: IML: Heat riser rotation?



NOT a dumb question, If memory serves me correctly, the valve rotates
clockwise. There should be a stop pin which prevents the valve from
opening past center.If you feel a lot of restriction opening the valve,
its possible to break the spot welds on the valve, and it will remain
shut.If you have dual exhaust, have someone listen to the right pipe
for a louder exhaust sound, when you open the valve.This is one of the
simplest issues for performance, and mileage that goes un-checked.When
we remove the manifolds, we remove the valve completely.Ya'll have a
nice day, Dave.

Â
-------------- Original message -------------- From: therichardsonfamily@xxxxxxxxxxx 

> Dumb question time:
>
> On a '67 440 (from an Imperial - required content), looking at it
from the
> passenger's fender, which way does the heat riser rotate as it opens?
I suspect
> mine does not work correctly and I want to wire it open.
>
> Dan Richardson
> 300L Family Heirloom
>
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