Yes, the heat riser has everything to do with the diversion of exhaust gases from the passenger side cylinder head exhaust manifold, through the bottom of the intake manifold and then into the driver's side exhaust cylinder head, and then into the driver's side exhaust manifold.  The heat riser spring provides resistance to the opening of the plate that restricts the flow of exhaust gases out the passenger side header.  As engine speed increases, the volume (quantity) and force of exhaust gases exiting the passenger side cylinder head increases and the heat riser valve opens against the spring pressure permitting the increased quantity of exhaust gases to flow out the passenger side exhaust manifold, through your cross-over pipe, and into and out the driver's side exhaust manifold, and into the exhaust header pipe and on to the muffler below. 

Even if you have the heat riser wired in the open position, some exhaust gases will still likely flow from the passenger side cylinder head, through the bottom of the intake manifold, into one of the driver's side cylinder head exhaust ports, and then into the driver's side exhaust header and then out of the header and into the exhaust header pipe.

To restrict the quantity of exhaust gases passing under the carburetor (which otherwise burn the paint off the two exhaust cross-over branches of the intake manifold) some of us use the style of intake manifold gaskets that Ford supplied on some truck y-block engine application.

Here's a picture of the standard intake manifold gasket originally supplied by Ford for passenger car use.  Click the link below.
http://www.ebay.com/itm/Fel-Pro-MS9361B1-Gaskets-Manifold-Intake-Ford-Mercury-Ford-Y-Block-Set-/331549408964?fits=Make%3AFord&hash=item4d31e27ec4:g:4I4AAOSwBLlU~~LQ&vxp=mtr 

Here's a picture of what Ford originally supplied for use on some truck applications.  Note the restrictions in the size of the center exhaust cross-over ports in the link below.
http://www.ebay.com/itm/FORD-CLUB-1955-1962-Y-BLOCK-INTAKE-MANIFOLD-GASKET-SET-9433-01-/360814069198?hash=item540231c5ce:g:cFYAAOxy6-tR-U~N&vxp=mtr 

Some of this is a lot easier to understand IF you have the opportunity to see how the y-block cylinder head is ported with regard to one exhaust port in each side of the engine.

Hope this helps.    


NoShortcuts
a.k.a. Charlie Brown
near Syracuse, New York

Thank you for all the information , you live up to your namesake. : )

I figured it was probably for heating up purposes. I guess I figured you didn't need it because like you mentioned, we usually take our cars out on planned outings with no rush and thus let the car heat up at home first.

I remember reading about who the Y-block funnels exhaust gases through the intake manifold to help heat up everything and get the car going which I guess was a new idea then at least how it was written about. I was wondering if the heat riser has anything to do with that.

Half-dude.  The purpose of the carburetor choke and the exhaust manifold heat riser is to improve the drive-ability of our vehicles when they are initially started and the engine's are not at normal operating temperature.  IF you regularly use your car in early Spring, late Fall or Winter weather, the carburetor choke and exhaust manifold heat riser are important if not critical to make your vehicle safe to drive when you first start out to go anywhere, particularly if you are operating in traffic.

As hobbyists, many of us do not operate our vehicles on any kind of a 'need-to-go somewhere now' basis.  Many of us do not use our vehicles in the Winter at all because of the adverse weather and road conditions.  -We put the vehicle in storage for the 50 degrees and lower months.  The exhaust manifold heat riser prevents carburetor icing and flat spots in carburetor operation by improving fuel atomizing and preventing fuel and air separation (fuel drop-out) in the intake manifold or cylinder head intake porting passageways. 

IF you retain your heat riser valve mechanism, it's important to maintain it so that it does not get stuck in the closed or partially closed position.  Check its free movement regularly.  Personally, I use a graphite like material as a lubricant to assure free movement of the valve shaft mechanism.  Dri-Slide is one such product that has molybdenum disulfide as its base.  Dri-Slide will penetrate into the shaft and bearing surface area of the mechanism.  The fluid carrier dissipates at room temperature and leaves a rust preventative and dustproof lubrication that is effective from -50 degrees to 750 degrees according to the manufacturer.

In the early Spring and late Fall, at temperatures of 50 degrees or lower, IF you only drive your vehicle after warming-up the engine first, I believe you'll find that you don't need the heat riser to do it's intended job and can simply wire it open.

Hope this helps.  


NoShortcuts
a.k.a. Charlie Brown
near Syracuse, New York

If you have a single exhaust car would you suggest leaving the heat riser alone? I've thought about tying it open myself because the one I have the spring makes a lot of extra annoying noise as the exhaust opens and closes the valve.

I replaced the heat riser with the spacer in both of my YBlock cars with no problrems.


54 Victoria 312;  48 Ford Conv 302, 56 Bird 312
Forever Ford
Midland Park, NJ

That's a lot nicer piece than the one I got from Larrys TBird Parts.

55 Glass Top.  The exhaust manifold heat riser was originally located on the passenger side of your '55.  Consider tying it open OR replacing it with one of the FoMoCo heat riser size spacers (the spacer is held by the exhaust manifold bolts, but has no valve mechanism in it).

By doing either of the above suggestions, both sets of exhaust pipes, mufflers, and tail pipes will get to normal operating temperature together and eliminate any condensation in both branches of your system when you operate the vehicle.  With the heat riser working properly, it takes longer to eliminate the condensation on the passenger side and you will likely find yourself needing to replace components on the passenger side (mufflers, tail pipes) while everything seems to be fine on the other side.

Click the link below to see what one of the heat riser replacement spacers looks like for your engine.  This is an eBay listing.  -Not mine.
http://www.ebay.com/itm/Ford-Thunderbird-Exhaust-Heat-Riser-Spacer-Cast-Replaces-Heat-Riser-Valve-/111954921586?hash=item1a11088872:g:8IIAAOSwEK9W~nTM&vxp=mtr

Food for thought.  


NoShortcuts
a.k.a. Charlie Brown
near Syracuse, New York

Hello what side does the heat riser go on a dual exhaust 1955 272 engine drivers or passenger thanks