There is an exhaust gas control valve shown in the Ford Truck Manual that is installed between the crossover pipe and the rh manifold. Some pictures of stock exhaust setups that I've seen of other members trucks do not all show this part. Some photos show that the crossover is bolted directly to the rh manifold.

I'd like to know what this part does and why it is apparently optional?

Thanks,
Doug

 

its for warming your motor at start up.theres a spring that opens it when hot.when cold its closed and forces exhaust through the intake to warm the carb.

 

Yep, that is what it is for, I think my gallery pic of my y-block catches a glimpse of the one on my y-block(sorry, just looked and the top radiator hose covers it up, but it's just a valve that inserts between the manifold and crossover pipe), well, it isn't going to be my y-block any longer, but yeah, you get the point.

 

It is called a heat riser and like the guys just wrote it is closed until the engine warms up. It is a bi-metal spring. It forces the air from the exhaust on the left side up over the intake manifold to heat things up faster for smoother running. By "optional" do you mean was it an option from the factory? No. It was standard on all V-8's. Is it optional to keep it on or not? Yes, I guess so. The engine still runs with it off.

abe

 

In certain conditions the carburator can ice up causing very rough running when cold or maybe not run at all. You need high humidity and cold weather to create such conditions. Later enginers had hoses going to the air cleaners that came from the exhaust pipes to heat the air to prevent the icing,

 

You are right on.

Fred

 

thanks guys...I guess I won't need it in Arizona

 

I am not an expert but it is for more than freezing and icing up. It is for warming up the engine faster so it runs more effciently and burns gasses better. Will it run without it? of course. But I think Ford thought it would run better with it regardless of the climate.

abe

 

I keep them in place. You should always let the engine come to full operating temp before driving, and that little ole valve cuts that time down drastically (if it's working).