Y block Billy (3/16/2013)
Something doesn't appear right with that video, that spring is turning 2 revolutions for every rocker lift, I watched other videos, the one of the valve spring at 7000rpm and that spring wasnt turning but 1/16 per rocker lift, I also watched a few other videos but they were overhead cam and could not really see the turning action well. I know the valves and springs turn and such, but that appears excessive and it does not stop when relaxed, I can see it revolving a quarter turn or so after each compression from the rocker but it should slow down or stop between compressions shouldnt it?
What’s not shown in that first video that was posted is the rpm that the engine is running at. Depending upon the video frames per second speed and the engines actual rpm, the valve action can be quite misleading. The fact that the spring is constantly rotating is a good indication that the video is only catching some of the valve action and not all of it. While the spring rotation in that video seems severe, I suspect the rpms of the engine in that particular video was way up there.
Here’s the link to another video where the engine is held at 7000 rpms which gives another view of valve spring rotation. This one is not near as severe as the earlier posted video.
http://www.youtube.com/watch?v=i_NpzU4pGjc&NR=1&feature=fvwp
And here are couple other videos where the rpm is slowly increased thus demonstrating how the frames per second of the video recording device gives a misleading view of the speed of the valve action at the various engine rpms. But both of these videos give a good view of valve spring rotation by watching the retainer. Without some reference marks on the spring itself, it’s difficult to discern the actual valve spring rotation in the first video but the retainer does tell the story. The stripe mark on the spring in the second video helps to clarify the actual spring rotation though. Both of these videos give a running narrative of the rpms as they are being changed.
http://www.youtube.com/watch?v=_REQ1PUM0rY&NR=1&feature=endscreen
http://www.youtube.com/watch?v=cfGg15WgSEU