Do the cylinder heads have additional items that get attached to them? Bolted etc
Top meaning you have one main Assembly, next level would be a sub-assembly inserted into the Top Main Assembly etc...
Rule of thumb that I like to use is this, anything that is welded together is a Sub-Assembly, anything that can be bolted together as one unit can be a Sub-Assembly and so forth... Normally my Top assembly has very little single components that are not in a Sub-Assembly...
Just a stab at your Engine
Main Assembly = All the components required for it to run
An example for a sub-assembly =
Cam Rod Sub-Assembly =
Cam, Rod, Bearings, Rings, Piston etc... (I have no idea what else would be included or eliminated)
Carburetor Sub-Assembly =
All the components for a complete unit, after assembly this Sub-Assembly would be ready to bolt on the engine block
Water Pump Sub-Assembly =
All the components for a complete unit...........
So, my guess off the top of my head, when opening the main assembly, your feature tree would only have sub-assemblies and very very little other parts. Also, most companies will setup their main and sub-assemblies on how the units are sold, when you buy a carburetor kit, what comes with it and so forth.....
They should be in the sub-assembly that they are bolting on - For kicks and giggles, check what is included in a carburetor kit, my guess is all the gaskets, bolts and parts to "Install" it on the engine block, the same with the water pump, cams/pistons.
Oil ways should be a good example and is another thing that would be a Sub-Assembly, the bent pipe with the thread nuts on each end, therefore when you go to buy the pipe, you don't just get the pipe you also get everything included that would be needed to replace a faulty pipe.
Good place to start is an operators manual, can you picture the service guy trying to find a certain bolt if it's buried in the top main assembly, no he looks for the sub-assembly first, like the water pump and then he can find the bolt, otherwise it would almost be like trying to find a needle in a hay stack trying to find it.
So pretty much as long as my cylinder heads are not sub-assemblies of sub-assemblies of sub-assemblies and so on, and they remain one step under the main assembly I am about as much top level as I can get. It has nothing to do with it's position up or down on the feature tree correct?
That's correct - Feature Tree order has no recognition of Sub-Assembly levels, the only thing that happens in the Feature Tree is that SW will rebuild or load from the Top going to the Bottom...