0+ (Unillustrated Parts)  
1+ Inlet camshaft  
2+ Timing ring  
3+ Exhaust camshaft  
4+ Tappet  
5+ Inlet valve  
6+ Valve spring seat  
7+ Valve spring  
8+ Valve collar  
9+ Valve cotter  
10+ Blind rivet  

The part numbers in the assembly image below relate to the product number in the table. Clicking on the part number will open up the relevant part details.