i was wondering why i haven't ever seen any cylinder heads for cars that do what some ducati motorcycles do. Instead of using springs to close the lifters with the rockers to open them, they actually use 2 rockers, one that opens the valve, and one that closes the valve, eliminating the power needed to open the springs and the springs themselves, which are limited to going only so fast.
here is what im talking about.
http://www.seastarsuperbikes.co.uk/ducatiengines.html
or would this just not work for our types of engines?

 

What you are referring to is known as a desmodromic valve.

Instead of trying to recreate the Wikipedia entry here is a link. http://en.wikipedia.org/wiki/Desmodromic_valve

 

Interesting read

 

Complicated system valve clearance needs to be checked and shimmed every 12k miles (I know the older ones say 6k). I believe Ferrari tired to run it in F1 and it was outlawed.

 

I have one of the older Ducatis, and although I don't mind adjusting the valves every 6,000 miles, that's only because I don't ride the bike as often as I drive the car. With 6k (or even 12k) intervals on my car, I'd be adjusting the valves several times a year. Plus, to really do it right, you need to buy a full set of intake shims and exhaust shims, and they're not cheap. You can get by with less than a complete set, but that means you have to check the clearances, order the shims you need, and then wait for them to come in, so in the meantime, the car would have to stay off the road or you would have to put everything back together and then take everything apart again when the new shims arrive.

Regardless, the biggest advantage of desmodromic valves is that they completely eliminate valve "float", regardless of engine RPM. But valve float is no longer the problem it used to be, thanks to advancements in metallurgy and valve design. Now, you can have engines operating at 8k, 10k, or even 12k RPM without worrying about valve float.

As you mentioned, there's also a power advantage to desmodromic valves, since you're not having to overcome spring pressure to open the valves, but horsepower is cheap these days - we're no longer having to eke every last bit of performance out of 60-horsepower engines. The power gains would be pretty negligible compared to the extra manufacturing expense and maintenance, so it probably wouldn't be worth pursuing for anyone other than a race team. I suspect Ducati continues to use desmodromic valves for reasons of traditions as much as performance reasons.

 

The valve adjustment intervals will kill you. About 10 years back I was looking into Ducati's at a dealer, and was quoted much shorter than 6K valve adjustment intervals, and at least a full 8 hours if not more time to do the job right, for two cylinders no less. Not cheap.
F1 engines can spin to 20K RPM partly due to pneumatic valve springs. Get any float, just crank up the pressure. Easy fix.

 

I don't remember the Ducati valve adjustment interval ever being less than 6,000 miles, and my current Duc is a 1998 model.

Eight hours of labor sounds a bit high as well, even if you were looking at one of the 8-valve models like the 916. Four hours is closer to typical depending on the model, and that includes checking/replacing the cam belts as well. I've gotten lucky on my current Ducati, because the last few valve checks have shown everything in-spec, so I didn't have to replace any shims. Just having to check the valves takes a LOT less time than actually having to adjust them.

 

I guess that shows one of two things. Either the dealer was conservative, or was going to lighten my wallet like most of them do. Good to hear they're not as troublesome as it was made out to be.

 

Almost any dealership is going to try anything to lighten your wallet.

When I had mine I paid one the mechanics to do it after hours for 175.00 instead of the 500.00 that competition accessories wanted.

He also said 6k was really just an inspection and that 12k was really when they would be out of spec enough to need adjusted along with new belts.