The valve is the part with the spring around it; the rocker is just what its name implies - they sit atop the valves and transfer the action of the pushrods (sticking up opposite the valves) to the valves so they open at the correct instant.

The bit about the Volvo B20 having a wear pocket in the underside of the rocker where it contacts the valve is right. You can use a standard flat-bladed feeler gauge to set the valve-rocker clearances, or do as I do, which is just a tad more involved, but gets your clearance closer to the original (pre-wear) specs.

I use a wire-type feeler gauge, which has blades of different thicknesses of hard steel in a 'U' shape, with the bottom of the U being flat instead of curved.

By inserting the flat tip of the U tongue between the valve stem and the rocker, you have to line it up so it is directly in line with the rocker so it will slide up into the worn, cupped area.

You sould feel just the tiniest bit of drag on the feeler gauge when the gap is set correctly.

There is also another type of feeler gauge that you may be more comfortable with; it's called a "go/no go" gauge. The blades of this gauge have one thickness at the tip, and then it steps up to the next thicker gauge; say a .020 blade would be .020 at the tip, then go to a .025 thickness. If the .020 goes in, but the .025 doesn't, you have your setting.

I once posted a diagram of how this is dome, look in the Image Library under Technical...Heck, let me go find it for you...

OK, apparently there is a problem with the image library; I wasn't able to pull up the correct set of images for Technical.

I've reported the problem, so it should be resoved soon.

Go to the image library and look under Technical and 444-544. You will find one of my photos or drawings there, (barongrey) so you can click on the Show All link next to my user name. This SHOULD bring up all my uploads in that particular area. You'll have no problem identifying the valve adjustment diagram.

I plan to do some fairly major work on my car this coming week, and I'll shoot new photos, including a real picture of the wire gauge and how it is used.

In the interim, by all means use a flat-blade gauge and get your valves adjusted. Your car will run much better.

Remember that after setting the gap, to move the rocker up and down with your fingers just to make sure you haven't overtightened it. There should be just a small amount of movement. If they won't move, they're too tight. If they're really loose, try adjusting them again.

If you need help, come back and post a request...I'll be home Sunday or Monday and I can take pictures and walk you through the procedure.

Don't be intimidated; this is an easy task!

Steve