The B21/23 and B200/230 series of engines are overhead cam with solid cam followers. Valve adjustment is made by changing shims held in the valve depressor. The valve depressor looks like an inverted straight sided bucket, and the shim snaps into the shallow (up) end. Under each valve depressor there is a little rubber cushion which serves to take the "click" out of the actuation of the valve. This little rubber cushion is called either a "husher" or "valve absorber" depending on who your are talking to. These hushers snap into the valve keeper. The photo below shows a new husher alongside a very used one. The rubber looses its elasticity over time and heat, and you get noticeable valve noise.


The next picture shows a new husher snaped into place on the top of the valve stem.


The last picture shows the head with valve depressors in place. I have used some Hylomar sealant to make sure I don't have any oil weepage under the front cam bearing cap.


I just picked this head up at the machine shop, and have been adjusting the valve clearance. If you have new hushers installed it makes it tough to feel properly with a feeler gauge. I complete the valve clearance process before I install the new hushers.
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john