In my opinion, the lesson regarding exhaust to be learned is in the answer to this comment.
Originally, Fenton headers were offered with what some call a "heat box" on the rear header. This "box" had the same configuration on the top of it as the stock exhaust manifold and bolted to the bottom of the intake. This "heat box" was nothing more than an open passage way from the rear header into the box where the intake attaches, keeping continious heat to the intake. Later, because of the configuration of the 216 versus the 235 intake, Fenton went to the more common header set without the heat box and developed the plugs in the headers with the two tubes that attach to each header and run to a plate on the bottom of the intake, suppling heat to the intake. In so doing, the exhaust is "shared" between the two headers, or between the two sides. Here is where the equalization of the exhaust from each side works to together. It's not so much the lack of a one way flow as much as just the equalization of the exhaust from side to side to creat constant a heat source.
It seems to work for a heat supply, but I agree, it doesn't seem like an equal flow would take place. I would suggest a plumbing pipe nipple pointing down on one exhaust pipe and above it another plumbing pipe nipple pointing up. Take the exhaust from the one pointing down, to a plate on the bottom of the intake and send it back out the other pipe to the nipple pointing up to create a circular motion of the exhaust to the heat plate. This would do more to move the heat and it would avoid the equalization process or the build up of any pressure between each side of the exhaust. I used this method on my truck for awhile and it seemed to work well. I now have a heat box rear header and, frankly, I'm not sure I could claim it works as well as the circulating set up. It heats fine, but it seems to take longer.
Finally, mixing the sides, or the front headers and the back header, by use of the tubes from each header does another thing.....something I do not like. I destroys the "rap-rap" sound of the Chevrolet six, the sound I originally fell in love with many years ago. Obviously, this means that method is not even a consideration.....at least for me.
Joe
