hi guys, i gots a annoying question, there is this round actuator and arm that is attached to my passenger manifold by the y pipe and i cant figure out what it is or what it does, looks useless. there was a line going to it and its not hooked up and the line went to the carb, it feels like the actuator closes and opens a butterfly valve in the manifold, thus reducing my flo, i cant figure out why this would need to be there?
any ideas? ill photo it later

 

The old name for it is "Heat Riser".

Auggie

 

When the engine was cold it would force the exhaust from one head to travel through the crossover under the intake and out the opposite side manifold to warm the intake up faster.

 

im talking passenger side, it looks like an actuator not a little heat shield, im also talking like its right in the end of my exhaust manifolds


edit, it really blocks off flow?from one head, is that even safe?

 

Listen to what Apeiron is saying because he has it right. This valve is normely open. When a cold eng is started and vacuum is applied to the actuator and the valve is closed. The exh. is routed through the Pass. side head under the int. manifold and out the driverside head into the exh.manifold. This system is controlled by a Thermiel Vacuum Sw. (TVS) and is usuelly located on the thermostat housing. When the coolent temp gets to 105*F (i think) the vacuum is removed from the actuator and the valve opens and the exh. goes out the pass. side exh manifold. If you store your car in the winter you really don't need this system but if you don't this really helps driveability in cold temps.

Auggie

 

i live in texas...winters are not harsh and i warm my car for a few minutes anyway, the thermostatic parts are not needed here.


a few questions,
-The exhaust can flow under the intake manifold?
-The actuator valve hasnt been pluged in to its line for a good while cause it wont stay together, if i leave the line in to it off does this mean it wont function, as in simply stay open?
-When i get headers this stuff falls off with the old manifolds, right?

 

ya, when i did my headers i had the same ? about it. but it's not on my car anymore and haven't have any problems. mine didn't have anything hooked up to it...well it did but they were soo rotted and rusted that it might as well not been hooked up. mine was held in place with the y-pipe just press between the mani and y-pipe...... but here's the thread

https://www.thirdgen.org/techbb2/sho...hreadid=235635

edit: ^^o ya, it has a pic of it too^^

 

I gutted mine & opened up the inside,but left the actuator rod w/vacum hooked up for the smog guy.