He did use single springs for the break in. He claims when he first assembled it with the intake off none of the lifters were spinning. So he backed off the rockers some and turned it over with the starter. Still only a few were spinning. He torqued the rocker shaft back down and spun it over, no spark plugs, until all the lifters were turning. He said some turned faster than others but all were turning. He then took the rocker shafts back off, popped the lifters up and relubed the face. Reassembled everything and fired it up. He said it fired right up, ran it up to 2200 and checked the timing, it was retarded 6 degrees at 3000. He set the timing and let it run for 30 minutes varying the RPM for the duration but never went below 2000.