Yes definatly. 20 minutes is way to long to run it out of the water. but make sure you hook the engine up to some sort of water supply. a good idea is to get a preasure regulater like the ones used on motorhomes when hooking up to city water. your water supply at the house is most likely set at 35 psi, try and regulate it to about 10-12. watch the temp gauge. you may want to have someone else with you while breaking in the cam just in case you need to adjust water supply, or any other task as you will be at the throttle. just a thought.