[steve s]

For several years (college) I ran my heater without any scoop, just a home rigged tap on the rubber radiator hose. It seemed to work okay as long as I had a thermostat above it. Like Jim said, the back pressure from the stat seemed to help. Also, it really made a difference whether I used a 160 or 185 degree stat. I'm currently using the tap in the thermostat housing sold by Vintage Precision, which looks to me like it would provide plenty of back pressure. That works fine with the 160 stat that came with it, but the car is no longer my daily driver in the dead of winter. It's kind of nice to be able to put that over-zealous Model A water pump to some good use, other than pushing coolant out the overflow.

Another suggestion: I installed the switch controlling the heater fan in the kick panel on my wife's side of the car--HIGHLY recommended! I never bothered to rig up a remote cable to control a flow diverter valve to fine tune the coolant flow (and temperature) thru the heater core. I did construct an elegant diode array and multiposition switch in a failed attempt to make the blower motor multi-speed. I did install a shutoff in the heater hose under the hood, for use in summer time. But in cool weather, it's one-temperature, one fan speed, either OFF or blasting ON--under my wife's control. Works for us!