I tested the flow on my 7.4's by disconnecting the input line at the thermostat housing and connecting a random piece of hose to the line so that I could run the engine briefly to fill up a 5 gallon pail that I had in the bilge. Took about 20-30 seconds as I recall. I made sure the engine was warmed up so that it would idle properly
Make sure not to get twisted up in the belts and pulleys at the front of the engine
