Onegammyleg: I don't disagree with you, as far as the cam profile defining when the valve's can close. However, the fact is it is the spring pressure that makes the valves follow the cam profile and if you put to weak a spring on them, their going to float.

My point wasn't that you couldn't use less spring pressure. My point was that I don't like dismanteling and rebuilding engines, unless I have to and in my perspective, the potential gains are so small as to be virtually insignificant, in comparison to the problems with goofing up the valve's.

If anyone has the inclination to try this, go for it. I don't think your going to see any measurable gains, but hey, I just am not into rebuilding something if I don't have to.:rolleyes:

Good point. Honestly, I think I've only ever taken the valve springs off a head once, and that was so long ago I honestly don't remember how difficult it was. Also it was a pushrod engine.

Hi Gary

Well . .discounting the cam change there still would be measurable gains just by the springs alone.
Have you ever had a head on the table and tried turning the cam sprocket by hand ?
If you had you would appreciate that they don't turn easily , and when others in here are doing almost everything apart from shaving door handles off they probably are looking for that 1 horsepower loss/or advantage.

Even after the many years that I have rebuilt engines I am still amazed at what people expect them to do.
Idle smoothly , run well across a huge RPM range , live a long time and give good gas mileage.(and now days pass smog tests)
Its an amazing trick really that they do it so well.

But one of the problems with having an engine that can run across a wide powerband is that its not going to work PERFECTLY across it.

That is why ,,if a person desired to do so, modification to narrow the powerband (cam, springs and reduction in head port size) you could increase its efficiency in a lower RPM range....which should/would improve FE at those revs.

The car would loose its maximum power and flexibility would be less (no more tower out bogged Hummers in the Metro).,, and of course JUST a spring change (without a cam change) would be asking for trouble.

Of course extreme FE mods arent for everyone ..otherwise we would be all driving around in white metro's with clear vinyl sheeting stuck to the front and back to improve the aerodynamix . :D

"Of course extreme FE mods arent for everyone ..otherwise we would be all driving around in white metro's with clear vinyl sheeting stuck to the front and back to improve the aerodynamix . "

Don't you mean White Civic Hatch's? I know it's hard to tell sometimes. :)

Hehe , your rite ,its hard to see under all those mods. :D

i agree. definitely.