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As the title says, what is this?

Thanks!

Re: What is this?

As im typing this, im sure somone else is also...

Its a heat riser valve. Vacuum is applied to the diaphragm(the big can thing with the nipple on it) and closes a butterfly valve. This forces all the exhaust gas threw the head, intake, and out the other head warming the engine up faster in cold weather. The vaccum line should be in line with a thermostatic vacuum switch that will shut vacuum off once the truck warms up and therefore, re open the butterfly valve. Between the exhaust manifold and exhaust pipe is a piece smiler to this,
http://t1.gstatic.com/images?q=tbn:A...Jsk2eZgEYAxAgQ

thats what the diaphragm is opening via a rod that goes from the diaphragm to the butterfly valve.

Re: What is this?

http://t1.gstatic.com/images?q=tbn:A...0jCQEf5atq6TnN

Assembly looks a little like this.

Here is what mine looks like,

[IMG]http://i597.photobucket.com/albums/t...i/IMAG0783.jpg[/IMG]

Re: What is this?

Quote:

Originally Posted by y5mgisi (Post 4462869)

Thanks for the quick reply. What is the vacuum source for this valve? I did notice what appears to be a TVS on the thermostat housing with the top fitting going to the carb and the lower one being open... Can you send me some pics of your setup?

Thanks!