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Thought I'd share my latest project with everyone. Maybe someone will find it useful. As we all know, the original cardboard duct linking the underhood heater core to the firewall on many of our cars is less than durable. I got my '51 Windsor with a galvanized steel, riveted, duct taped abomination in place of the original duct and I couldn't stand to look at it in the engine compartment (there are a lot of other interesting no-noes in this picture too; see what you can spot): Unfortunately, replacements are either very expensive or very low quality and sometimes both, so I didn't like that option. I decided to make my own out of fiberglass using the lost foam method. This is where you make the inside shape of the part out of styrofoam, lay up fiberglass on the outside and then melt out the foam core with acetone. More on that further down. First I needed to get the rest of my heater in working order. My heater control valve under the dash was missing and replacements are expensive and contain 60-year-old rubber, so I did some poking around and it turns out the 1975-91 Volvo 240 uses a very similar valve; in fact it's made by the same manufacturer, Ranco. I decided to see if that would work. Plenty of old Volvo 240s at Pick-n-Pull, so a valve was easy to find. It's hidden in the driver's footwell behind the plastic cover to the right of the gas pedal. You have to disconnect the heater control cable, two heater hoses, and extract the capillary tube from the adjacent heater duct. The right way to do this is to pull the whole dash out of the car, then separate the halves of the heater box and pull out the capillary tube. I expedited this by breaking the plastic duct around the capillary tube grommet and pulling it out the new hole. Apologies to Volvo enthusiasts. Back in my garage my Chrysler control cable needed the loop clipped off the end and then it was easily attached to the Volvo control valve: A couple differences between the original Chrysler valve and the Volvo valve: the pipe/valve assembly is rotated 180 degrees, so the inlet faces away from the direction the control cable comes from. This means either the control cable or the heater hose that connects to the cylinder head must loop around to the far side of the valve. The pipe/valve assy could be uncrimped and installed the other way, but that seemed like an invitation for leaks and my control cable was long enough to make a big 180 degree turn under the glove box. I installed the valve with the short (inlet) pipe facing the cylinder head: I also had to gently bend the inlet pipe away from the firewall to be able to fit a heater hose and clamp on it. I had to cut away some of the firewall sound deadener on the inboard side as well, to get a better angle. The original Chrysler part has longer brass pipes that aren't such a tight fit. I put a tinnerman nut on the firewall and one on the heater valve; one screw is installed from the engine side and one from the interior side, since the pipe blocks access from the outside. I coiled up the capillary tube (don't kink it!) and stuck it into the interior heater duct through a conveniently damaged area so it will pick up heat: