Well I just came back in from doing MP's cooling system "test". Not very scientific, but all it consists of is bringing the engine up to operating temperature with the radiator cap off and watching the coolant flow across the top of the radiator. There was very little flow with the engine at idle, you could see it pick up some, but not greatly when you gave it gas.

Then I did my own test for air flow. I took a 8.5"x17" piece of corrigated cardboard, and put it in front of the radiator and trans coolers with the engine idling. The fan sucked the cardboard up tight against the trans coolers and held it there, so I'm definitly getting adequate airflow at idle.

I just re-read Sanborn's Oval track cooling tips at Rapid Robert's suggestion ( ), and I think my next move is installing a 8 blade pump with a homemade Flowcooler disc (since they don't sell them any more ) and a high flow thermostat.

If you look at the stock impellers, they are just a piece of flat steel, cookie cuttered, then bent into shape. This makes a cheap but leaky impeller, prone to cavitation. They clearly were more so worried about keeping assembly costs down rather than creating a superior pump. The engineers and bean counters decided what was "good enough" and that's what we get in a stock pump.