5 things that changed how I build engines
Few things in the automotive world are as complex as building an engine. Not assembling an engine; building an engine. It’s similar to cutting a diamond: The beauty of the finished product is simple, but the process—taking the time to ensure proper setup and function at every step—can be intense.
Becoming a professional engine builder requires years of experience. I’m definitely still an amateur, but these five things helped me make huge leaps in my own engine-building process.
Layout/space for layout
One of my first engine-rebuild jobs wasn’t even the full engine, just the top end of a vintage thumper after it was destroyed by a short and torrid love affair between intake valve and piston. I set up shop in a friend’s garage. We pulled bits and pieces off with reckless abandon, stacking them on the motorcycle lift under the bike. Only once we reached the reassembly stage did I realize all the parts we needed were a jumbled mess.
Today, I prepare my workspace. I prefer to have enough room to lay out each and every part: They don’t have to be organized very strictly, but nothing is stacked, in a box, or otherwise hidden from sight. Attention to detail is one of the most important resources in engine-building; I don’t want to waste it on making sure parts didn’t fall off the table or get jumbled underneath it.
Honda famously requires all its assembly-line workers to wear white head to toe: The process should be so clean that the uniform stays white. I’m not a professional engine builder, but I did stay at a hotel last night—and I kept the towel to lay on my workbench. Only once a part is fully ready to assemble is it placed on this now-sacred space. Depending on the component, I might even wrap it in a plastic bag or container first.
That clean white space is where I first assemble the engine—mentally. I can visually take stock of the parts and pieces and know that I have everything, and each component is properly prepared. This prevents me from being surprised or having to source something on short notice: If a part I thought was cleaned and ready needs additional work, I address it now, before assembly starts.
Write it down
A failed seal once forced me to rebuild an engine I had already assembled. As I took the engine apart, I did the standard “while I’m in there” look-around. The only problem was that I couldn’t tell whether the wear on a given part was new: Certain pieces like rocker arms are totally safe to reuse if still in spec, but failing to document the wear in specific terms leaves me open to confusion when trying to diagnose other issues. Did I re-use a worn part, or did I produce that wear because of a sloppy assembly?
Eliminate that game and draft a personalized cheat sheet. Anything that can be nominally measured gets touched by the digital calipers before being final-assembled. If taking a measurement isn’t possible, document a part’s condition, including any flaws that you might need to monitor or allow for in the future.
These sheets are also handy if any of my engines go up for sale before I run them or put them in a bike: The buyer can see from photos and notes exactly what they are buying.
Understand each part
Once I started noticing each individual piece of the engine worked, my brain was able to prioritize. Suddenly I worried less about using factory hardware to hold on a side cover and obsessed instead of the one little lip seal that ensures oil coming out of the oil pump goes through the crankshaft to the rod bearing.
This mental process is also great for troubleshooting issues, especially if, like me, you use some components outside of the engine’s original design parameters, and thus deal with problems and fixes that the original engineers would never imagine. If you truly understand the system, you can more quickly deduce which component is not doing its job.
Just like it takes a couple of watches of Inception to know what the hell is going on in the second half of the movie, it takes more than one rebuild of an engine to fully understand what you are doing. It’s tough for us home garage folks, but rebuilding the same engine multiple times is an awesome way to learn a lot in a short amount of time.
Your first time through a build is often spent just trying to not do things wrong. Then, as your confidence builds, you start asking why this works, not how it works. Suddenly you are primed to understand what improvements you can make and, if you seek more performance, what is a good spend of your time and money.