This.Exhaust.Valve.... What is it?

[pagrunt]

If you intend to use the car in Winter, then you should repair the EFE valve. They are available and it serves an important purpose. If not, then either wire it open or remove it and use the casting without the valve. What it does is- in the closed position it forces all the exhaust gas from that side- back up through the exhaust crossover in the intake manifold- then out the passenger side exhaust manifold. If it stays shut you can boil the fuel in the carburetor. Once the motor heats up it opens and both sides flow normally.

After nearly 30 years of making it look like I know what I'm doing now you have me rethinking about not using a EFE on the Monte (it'll be the earlier temp spring type I'll be using if I do.)

 

[Bonnewagon]

Well, as always, the factory knew what they were doing. The old heat riser valves that had a bi-metal spring and a counter-weight worked the same way. The spring eventually broke or the shaft rusted causing major headaches so people just yanked them off. If it stuck closed the fuel boiled. If it stuck open cold weather warm-up took forever. Of course if your car is a summertime only toy then you don't need it at all. But I can remember many a cold wet Winter morning when I'm late for work and the motor is coughing and stumbling because it can't warm up fast enough. EFE stands for Early Fuel Evaporation. That is the fuel in the carburetor and if your choke relaxes before the intake is warm enough you get poor atomization and crummy running. This also pertains to the THERMAC air cleaner. The flex hose that feeds hot air off the exhaust manifold to the carb is critical to smooth fast warm-ups. You won't miss it in July but you sure will in February.