NOW for my next step. As has been mentioned here, using oil to a front oil cooler is less than ideal. Velocity uses it in their stock Lycoming installations since they do not have a water/coolant option. However, we do.

My question to the collective is; would it be acceptable to use the aviation oil cooler that is already installed in conjunction with my currant water coolant system. My thinking is that an oil cooler, if I understand correctly, is more "durable" and able to withstand more pressure than the standard water radiator. Of course, there may be reasons other than pressure that would factor in, I just don't know them.
 
There are no doubt specifications for heater cores from SAE. But they need  only survive about 25 pounds in normal operations, so they need only pass a (Guessing) a 50 PSI test. The aircraft oil cooler has much stricter specs in order to operate at 50 to 90 PSI so a good pass/fail test would be twice that rating or 160 to 200 PSI. The aircraft piece is furnace brazed the car piece is soldered. It is aluminum vice, tin plated brass or steel for the car piece. Check out the cooler to be sure the core has not swelled and closed off any air passages. This is also a failure more common in flat tube radiators.
 
Any place on the high pressure side of the engine or water pump is good for water pressure out. Any place on the suction side of the pump or water radiator is fine for water return. The small, light, cable controlled valves I was thinking about were for a Chevette (Maybe). Check with a big NAPA store. They have pictures of all of the parts they sell. Very use full in these situations.
 
Lynn E. Hanover