I have found an exhaust device just after the manifold on the right side (passenger side)I'm not a mechanic but it looks to be a butterfly/flapper device vacuum activated, what is this and why do I need it...I have a manifold leak same side..this device seems to make it worse at times.

It's called a heat riser. It is closed when the engine is cold, forcing the exhaust from the right cylinders to go across to the left side exhaust manifold by way of the crossover passage in the intake manifold. This warms the carburetor. It is necessary in cold weather and at smog testing stations. Make sure it is free to move so it opens when the engine reaches operating temperature.
On your 84, it is controlled by vacuum ported by a thermostatic valve that senses water temperature. Make sure the vacuum lines are in good condition.

Hey Bill

Thanks for the reply, I'm familiar with preheat systems but this does not seem to be set up in the configuration you describe, could I send some pictures as I am thinking that whom ever put the exhaust upgrade (Banks I think?)changed the original design, also the air preheat/intake setup is AWOL on my coach, any suggestions for new setup? I will be getting the manifold leak fixed as one stud is broken. I am handy with easy outs but is this somthing better left to a profesional? Thanks in advance for the help.

[This message has been edited by Sam (edited August 19, 2005).]

Sam, without a picture I can only make more bad guesses. However, preheating usually means heating the air before it enters the air cleaner, and is usually done by means of a muff around the front part of the rh exhaust manifold on Pees. A flexible tube goes from the muff to the underside of the air cleaner snout. There a vacuum control on the snout to control when preheated air is used. The heat riser heats the center of the intake manifold beneath the carburetor.

Pictures would be informative. I am interested in what this is if it is not a heat riser. Can you use photobucket so all can see?

Since your preheat is gone, you will need to have a muff over the right hand manifold. I will look into taking a picture of one on a friend's RV. It can be home made. The hose is available at auto parts stores. Is the hose spigot and vacuum valve still on your air cleaner?

Sorry for the late reply, to explain... we are currently living in our Barth for the summer, much as we did with our fithwheel. With fuel prices @ 2.65 a gallon our 750 mile a week commute to work is too much to bear. The money we save staying in our coach makes the payment. : ) Internet access is limited to weekends and (shame on me) company/work internet access, anyhow nuff excuses. I will stay late tonight and get the photo bucket set up I read your helpful posts on getting that site setup for another member. I should be able to get things online. Really appreciate the help