BrianCunningham

It's on a strobe light so you can see what's happening


yes, 7 tenths inch lift cam!

linutux

Does that have 3 springs?

jtkeller

Looks like 3 springs to me too.

BrianCunningham

The special flat ones are dampers. You can imagine what it would look like w/o them. The newer behive style springs don't have dampers.

Slalom4me

Thanks for the video, BrianCunningham.

Watch how much the tip of the valve stem moves around under the
end of the roller rocker after the valve 'seats'.

Three-component springs are not uncommon. Sometimes there is a
flat damper between and inner & outer. Or three round or ovoid wire
springs.

An example is COMP CAMS #26028-1: "engineered to deliver
performance in 1.000” lift engines while turning 9,000 to 10,000 RPM."

Seat Load: 346 @ 2.200
Open Load: 1074 @ 1.200
Coil Bind: 1.150
Rate(lbs./in.): 728

.

rbeckham

Wow - the secondary harmonics are wild. I wonder if this is the case throughout a significant rpm range, or whether this occurs only at a very specific rpm. Every system has a natural harmonic, so if it is the latter, it probably would be much less worrisome than if it happened, say, from 6500 to 7500 rpm.

Solofast

The valve opening and closing event is taking a little over 8.5 milliseconds (if we assume 180 degrees of noticable duration, yes I know it is longer duration, but I am just trying to get a rom idea of what is happening here so that is close enough). That is, at 7000 rpm the cam opens and closes in (about) 1/2 of one rev of the crank. That 1/2 rev of the crank takes about 4 milliseconds and the valve sits closed for about 12 milliseconds in which time I counted about 5 cycles of the spring. That leaves the frequency of the spring at about 388 hz. That is almost twice as fast a natural frequency as the valve opening event (one cycle in about 233 hz). So it is unlikey that the valve is driving the spring at it's first mode frequency, and since the system damps out pretty quickly it is pretty obvious that there is a good bit of natural damping in the system. There can always be higher order modes, but the spring doesn't seem to be resonating in them from the movie. If one of the spring modes was actually being excited here the whole system would have blown up in a hurry.

The spring has mass, and it will try to contine to move after the valve closes, but this looks like it is behaving pretty well, when you consider how quickly the system is daming out.

steve40th

Are there anymore videos of this for current set ups? Beehives and .600 lifts would be intersting to see.
Well I found one, about half way down on the left, Beehive video, right click and save.
http://www.compcams.com/information/...ry/Default.asp