Heat riser with Sisson choke?

[Lehman57]

I have a Chrysler industrial engine in a 1943 civil defense trailer pump.  It has a Sisson choke.  A friend tells me there is some sort of heat riser where the intake and exhaust manifolds come together.  But there is nothing about this in the manuals I have--not much on the Sisson choke either!  Can someone describe what exists here and how to adjust it.  A drawing or sketch would be great.  Thanks.

[desoto1939]

Yes there isa Sisson Automatic choke. This worked when the starter motor was engaged intot he flywheel. There was an electric line that ran to the choke and this then caused the choke to close on the Carb. There is a bimetal plate on the base of the choke and as the manifold got hotter then the bimetal plate released the tension and the  choke then would open up more until the point that the engine no longer need the carb to be chocked.

The heat riser is a plate that is where the two parts of the manifold are bolted together. This was setup to help the car owners that lived in cold weather areas. The heat riser woked via a wound spring so that when the weather was cold it would divert the heat up to the base of the carb to prevent the stalling of the carb and also prevent the ice buildup because the gas being vaporized.. 

 

The sisson cjoke is a spate unit and does not have any direct connection to the heat risor unit.  I have a manual on the sisson choke and how it works and how to set it up

rich Hartung

Desoto1939@aol.com

cell 484-431-8157

[Lehman57]

Thanks Rich.  So, there are no adjustments to be made to the Sisson choke.  I have some instructions about setting the Sisson choke.

[desoto1939]

yes the choke can be dajusted.

 

rich hartung

[dpollo]

Industrial engines s did not always have heat risers and some that did were set manually.  The heat riser is directly below the carb.  There is little direct relation between the heat riser and the Sissons choke unit.  Adjustments for the choke can be found in the automotive shop manuals and this has been discussed on this forum too.   The main advantage of the Sissons choke is that it closes electrically when the starter is engaged.

The electrical component is the usual point of failure.

[Lehman57]

Thanks again to rich and to dpollo whose first 3 sentences are the most meaningful to me.  As modified, the manifolds are almost invisible close behind the gas tank; I'll have to brush off some rust to see what I can see.  After I get a positive ground starter solenoid hooked up, I'll see how things work.

[Tom Skinner]

Vintage Power Wagon sells a Service Manual for the Chrysler Industrial Engine. I have a copy, and the Manifold Heat Control Valve is clearly shown on Page 62. In addition to that the Imperial Website has a technical/service tab that shows various Service Booklets on line on how to adjust a Sisson Choke. Actually using the Imperial Website will show you all of what you need to know without spending a dime (except for a few pages of paper copies you may require) for your shop use.

Tom

 

[Lehman57]

Tom, Do you have a website address or full name for Imperial?  Thanks.  I haven't found it yet.

[Alshere59]

 

[Lehman57]

Thanks Alshere59.  Got it; now to read to see if it says anything about the heat riser that someone, not on this site, has said is in the manifolds.  I doubt it though since there is no physical connection that I can see.

[DonaldSmith]

The Sisson choke and the exhaust heat riser are separate animals.  I looked through my photos to show the choke and heat riser.  Here are the best photos that I have -

The Sisson choke, at the bottom left of the photo: The wire link at the end of the arm works the choke plate in the carburetor.  The choke is on top of the manifolds.  A bimetallic spring in the choke partially closes the plate until the manifold heats up the spring.   The wire is from the starter solenoid, and the choke closes the plate further while the starter is cranking. 

Manifold heat riser:  The partially circular weight works against a bimetallic spring, to open and close a plate in the exhaust manifold.  I forget which way the spring and weight work, and which position is "open" or "closed", but when the engine is cold, exhaust gases are diverted into the chamber below the carburetor.  When the engine heats up, the plate moves and the exhaust flows straight past the chamber.  And that's all I have to say about that. 

 

[Lehman57]

Thanks Donald for the Photos.  I'll be saving them.  The first one shows a setup virtually like mine.  I don't think I have the weight and bimetallic spring shown in the second photo; apparently because this is an industrial engine on a WW2 trailer pump, but I'll have to get out a wire brush and mirror to be sure--it is virtually hidden behind the relocated fuel tank.  The heat riser (if there is one) apparently is manually set and is fixed from what I hear, but I have never seen any instructions on that.

[desoto1939]

if the engine is an industrial engine then they did not care about the heat riser. All they did was pull the throttle cable and kept the engine running at  faster speed because they were probably looking to get the most out of the engine to run some other piece of equipment.  The heat riser was mostly used in the cars that were used in the parts of the country that had winter type weather so that the carb did not ice over as I stated in my prior posting.

 

Rich Hartung

[Lehman57]

Thanks Rich.  That is the statement I wanted.  I had never seen it actually stated.  So, finding none is expected.