Re: IML: Heat riser rotation?

["Roger Casagrande" <rdc2382@xxxxxxxxxxx>]

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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