In the exhaust pipe (stock) of my 350 V-8, on the passenger side and just above the starter is what appears to be a valve that is vacuum operated. I THINK it is called an EFE valve (Early Fuel Evaporator), but am not sure. It appears to be part of the emissions system. I have searched high and low looking for informatiion on its purpose, how it works and what it does. Anyone know? I am especially interested in learning if the valve gate inside the pipe is open when the controlling arm is all the way forward or if it is closed in that position? I don't think it actually closes all the way off or the engine would stall. Maybe it just restrricts the exhaust flow for some period of time.

In my neck of the woods, the city and county are under pressure from the feds to lower ozone. When this happens in other parts of the country, it is just a matter of time before auto emissions inspections begin. I am just trying to get ready so when the time comes, I will not be pressed for time.

Thanks for any input.

That sounds like what we call the heat rizer valve, it closes off the manifold when cold to heat the engine quicker. if its not opening it can burn the valves and make the engine lose power.

You're right, it's the EFE. When cold, vacuum sucks it closed and the exhaust is directed thru the head, the intake and out the other head. This warms up the engine faster. It's for cold start emissions and driveability.

Most emssions testing don't/can't test at cold start up.


I am not 100% sure, but I believe it's open when the is extended in the normal/relaxed position. My arm rusted off and that's the way it's been for the last 6 months.