Re: IML: Heat riser rotation?

["Bob Merritt" <bob@xxxxxxxxxxxxx>]

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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