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So I've just learned how to take valves down and I'm pretty fascinated by the whole mechanism. I got a C-clamp compressor and took two valves out just to try. Went smooth.

A question: is it important to keep the order and put each valve and other parts in its initial spot? Or can I reinstall them randomly? Because keeping track of positions takes more work.

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    Very interesting question. In theory there should be no difference between any two valves but in practice people do keep tabs on the order. I'll be interested to see the reason(s) to do this myself
    – Zaid
    Jul 12 '15 at 8:26
  • If you just pulled them from underneath and didn't readjust anything on the cam you might be OK.
    – GettingNifty
    Jul 12 '15 at 23:35
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tl dr - It absolutely matters.

All of these parts need to go back into the same spot in the same positions for two reasons:

  • Sympathetic wear - Let's just say parts get used to each other. Once they have been meshed together for a long time, they are broke in together and work together. When you mix-n-match after the fact, unexpected wear can occur. Ultimately part failure is a distinct possibility.
  • Along the lines of the first, but more important, is the valves are lapped to their seats so they seal properly. If you mix and match, the valves will not seat correctly. Some of them might, but most of them will not. You will lose power and you'll be tearing the engine back down to do it all over again. If you have mixed up the valves, you'll need to lap them.

Let me just say, keeping track of valve positions is a lot of work. Not keeping track of them is a great deal more.

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    It's not just the valves either! Tappet and valve springs also should stay together as a unit. The difference between valves seating properly and leaking is a matter of fractions of a millimeter and switching parts between valves (or even putting replacement parts in) requires calibration and thorough expertise!
    – Stephen Arsenault
    Jul 13 '15 at 15:02
  • @StephenArsenault - Absolutely correct.
    – Pᴀᴜʟsᴛᴇʀ2 ♦
    Jul 13 '15 at 15:20
  • But you can't turn the crank at fractions of millimeters really so you put something long in the cylinder on the piston and make sure its where you need it.
    – GettingNifty
    Jul 27 '15 at 8:57

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