Thank you for your input and I will check out the site you mentioned. There is no doubt that with my life's work as a mechanic, tool & model maker and draftsman, that I am hung up on the mechanical aspect. If I can't measure it how am I supposed to build it, is definitely part of the problem.
As I look at the layouts on this thread I just can't help thinking about the system or method of first setting up the view and then being able to locate the components, bore spacing, valve angles, crank to cam centerline relationship, etc lets say for an engine cutaway. And also how each of those components change in size and ellipse degree as they recede along the perspective lines established for the view chosen. And that method has to adjust for every view chosen for each different illustration. That's a lot of stuff to keep track of! I guess I will need to put in a call to Yoda to help get my head around this.
I am going to throw a viewpoint in there that is very different from some of these folks, like Mr. Matthews, who would be a wonderful artist, no matter what his chosen subject. I also got my training in drafting in school, and after a couple of years doing it in Denver, came to California and really knew more than the teacher. He allowed me to experiment and to "learn" on my own the cutway styles by just copying them. I did this when I was 17, with a couple of LaTourette, Allington, Moore and Swaja pieces. I taught myself photography so I had reference that I could take with me, and started doing these things myself.
As a completely no-discernible-drawing-skill guy, I found that if I could get a photo of a car, only the exterior, could pick a couple of vanishing points, figure out a couple of the other odd axes in a car (engine sit or steering column, for example), with photos I could fill in the rest. Not sure where that is from, but it might work for you with your background.
Try picking a couple of drawings and reproduce them just to get a feel.
Think in blocks, like the body lines, or a complete wheel assembly, but taking into account what is around it ... don't just fill in area as you see it, but think in complete subsections to get things to look correct and not choppy and lumpy ... or is that lumpy and choppy???
Get a reasonable, not necessarily a hugely expensive, camera system and figure out how to shoot photos. As a basis, you can always use them to just copy and build an illustration.
Easy, and one can be taught .. I am proof that you don't have to be that skilled to pull this stuff off.
Since you seem to have some drawing ability, it will only shorten your learning curve.
I think everyone has to come from their own place, but just figure out something and draw something, even a copy. It will let you know how this stuff feels, you will see what is actually involved, and you can start creating your own style.
I may not be the best at this stuff .. there are many others here in the group who lay claim to that honor, but I started with no training or ability and taught myself, so it is something that is possible, just do it .. to steal a Nike line.