It is a single overhead cam aluminum head on a cast iron block. The cam is run by a chain located behind the front cover and under the valve cover.
The biggest problem area in any 22R is the timing chain. The chain is usually a single row chain with plastic guides. There is a hydraulic tensioner as well. NOTE that two different head and block heights were used. One up till 84 or so and another from then on. If you change heads, make sure you get the head that goes with your block. The exhaust ports will tell you what you have. Pear shaped are new, 2 hole exhaust ports are old. If the head/block is mismatched you will either have a chain that is too tight or way too loose.
Taking the valve cover off and inspecting with a light is the best way to know if your chain is in bad shape. If the plastic guides are broken, replace the timing set. These are availible everywhere and include new gears, a chain, tensioner, and guides. Northwest offroad sells some heavy duty guides and chains. I have used the standard stuff and had no problems. I really dont see the use in the heavy guides. I would rather have a plastic guide break and know something is up than have a steel guide grinding against the chain after its rubber coating has worn away.
See your manual for detailed intructions on chain replacement.