exhaust manifold lever?

[mateo1279]

So...

I was changing out spark plugs and ran across something I hadn't noticed before: A square piece of metal that leads near the (stock) exhaust manifold. I pushed down on it and it moved like a lever... anyone know what this might be.... if it is a mystery I can put up a pic...

Thanks

Matt

[Fred T]

Sounds like the heat riser. Is it in the collector? If it is the riser, there should be a coiled spring that closes the valve when the exhaust is cool.

On a 283 when the engine is cool, the exhaust is diverted from one side through a passage in the intake that warms the area under the carb, helping atomize the fuel.

[C10-Driver]

Originally Posted by Fred T

Sounds like the heat riser.

Vehicles equipped with a riser usually used a snorkel style air cleaner that was hooked up to the manifold with a flex tube. Hot air from the manifold would be drawn into the carb feeding it with warm air until the engine heated up.

If it is not being used anymore, you should wire it open.

[mateo1279]

That makes scene! Thanks for the tips!

-Matt

[Ham-er]

Yep many of these engines had both. The exahst diverter on one side and the intake damper on the other side.

[mateo1279]

so then are there any benefits to keeping these systems in place? performance or drivability wise?

[Ham-er]

Same old carb and intake? then Yes for cold drivability. Performance,nah.
Both systems just warm things up quicker basically, helps the fuel burn better till engine warms up, so helps when its cold.