Exhaust Pipe Component Mystery

It started out as installing the tires...which wouldn't fit past the tailpipes...which got cut shorter and reswaged...and i found this oddity where the pipe flanges up to the engine. What is it (other than rusty) , what does it do? is it necessary? And what does the pivot arm attach to? The driver side pipe does not have this throttle body looking gizmo- is that right? Should it also have one?

 

It is stock it is calles a heay riser I think .
It helps the motor heat up in the cold by keepin some exhaust backed up a bit.
My dads 61 impala has one I also think it helps work the old heat type automatic chokes on the older engines.
And it is suppose to be free moving but most of them freeze up like yours when not used for a while.

 

Yep, heat riser. That coiled spring holds it closed when cold, then as the motor heats up it slowly unwinds enough to open the exhaust up. It's called a "bi-metal spring". It's made of two different types of metal that expand at different rates when heated, that's how it moves. The lump-looking thing is a weight to help pull it open.

It's supposed to help warmup the intake manifold I believe, to help warm up the automatic choke mechanism. I think you can get new ones, but I'd bet most folks throw them away. If you're running a different choke arrangement, you don't need it.

 

Heat riser - there is supposed to be a flap valve attached to a flat coil spring. The valve deflects heat up to the rochester 2G to warm the choke up. Mine started to rattle a looooong time ago and was removed.

 

Agree with just about everything said 'cept I believe the heat riser was also used on manual choked carbs.

 

The exhaust gas diverted through the intake manifold warms the manifold - keeps the fuel vaporized when the engine is cold. Improves cold-start drivability. Also heats the choke stove if you have an automatic choke. In Texas you likely don't need it. Recommend you clean it up and put it back if it's not leaky or so rough that it won't seal.

 

Ah...I learn something new. Thanks guys.

 

so do you keep this heat riser or remove it? does a rusty coil still work? mine has the little choke stove type coil and the flipper valve that does pivot but its got a little ear on the spring that must hook somewhere