Question about a Mopar 440

[Sport-Trac 01]

Okay, this is a very precise question that I need an answer to. In my Auto Service 2 class, we are rebuilding a 440 engine that came out of a 1972 Dodge motorhome. I have been tasked with the manifolds, (removal, surface cleaning, sandblasting, repainting) and one of the manifolds (I only have one of them currently). has a butterfly valve at the end of the manifold, where the exhaust connects. What is the purpose of this butterfly valve and is it removable? Thanks for any help.

 

[bronconite]

Can you post a picture? It sounds like you're talking about a heat riser.

 

[Photog]

My 440 muscle car does not have this; but my 3.9 V6 does.

In the older vehicles, this butterfly might be used to create a certain amount of cross-pressure, to flow more exhaust heat under the intake manifold, or into the EGR system. You would want to make sure it is working properly.

 

[Curmudgeon]

That is the heat riser valve, and functions to channel heat to the intake manifold during cold start. Since you are in Michigan, I think it would be a big mistake to remove it. When it is functioning properly, it has no adverse effect on performance, and provides a huge benefit when it's cold.

What surprises me is that you are apparently taking some sort of auto repair class, yet you have to come here to ask a question like this. Have you asked the instructor about it? If the instructor doesn't know what a heat riser is, you have a serious problem.

JP

 

[Sport-Trac 01]

Thanks for the quick answers you guys. After talking to my local mechanic, who's also my dad, he reached the same conclusion. The 440 is going into a 66 Plymouth Fury belonging to a buddy of mine. The group we have that's working on this project is doing most of it independently from both our instructors, so we're trying to do most of it without their help. The younger of our instructors is helping a little bit, but this is his second year teaching here, and he's only 28, I think, so he hasn't worked much with older engines. The second instructor has been teaching for 40 years (he taught my father...) but he was busy and didn't come in today. I'll talk to my buddy tomorrow and tell him what you guiys have told me. I'll try and post pics up for you guys if you want some.