I have an 83 Z28 with LG4. on the passenger side Y pipe there is a thing called a heat riser I think. What is this thing for? And will it make a chattering nose under acceleration when the car first starts up?

thanks,
phil

 

It forces the right bank exhaust to go through the exhaust crossover passage and heat up the intake under the carb, until the engine is warmed up. It makes the car much easier to drive much sooner, when it's really cold out. Its official name is "EFE valve" (Early Fuel Evaporation)

Yes it definitely can make clattering noises. No it can't be removed completely, without altering the Y-pipe. But you can remove the shaft and blade, and plug the holes with 1/8" pipe plugs.

 

Phess,

Does your heat riser have a thromstatic spring or a vacuum actuator to operate the valve?

 

If you only drive the car in the summer can you just plug the vaccum source or does it also make a difference in the summer? Without vaccum is it open?

 

It uses vacuum.

Applying vacuum to the valve closes it. So you can disconnect its line from the EFE thermal vacuum switch and plug it.

 

They also make an open spacer that goes in place of the EFE valve. I forget who or where but I know they exist.

 

That's why I was curious.

http://www.firstgen.com/New%20Camaro...n%20Parts.html