This is part 6 of many in Limitless’ engine build. – be sure to check out the rest of the posts there. Prepping the pistons for installation basically involves hanging them on the rods, and installing all of the rings. While that sounds simple in practice, there’s a lot to be done. Apologies for the pretty awful image quality on this one…for some reason a lot of the pictures, despite my best intentions, came out somewhat blurry.
Step 1…Is What?
While this section of building an engine is relatively simple, there’s quite a few things to be done, and they all require care and precision to do properly. They also have to all be done in the right order. If you forget something, or get something wrong, or make a careless mistake…you’re really going to regret it, because then you’re going to freak out that you made that same mistake (or something else) on the 4 pistons you’ve already fully installed. Go ahead, ask me how I know…
Right off the bat, it’s important to note that this post only covers step one of a two step process – step 1 is to assemble a single piston, and step 2 is to install that single into the engine…and then you’d repeat steps 1 and 2 again 7 more times. You could prep all of the pistons first, and then install them all, but I much preferred doing both the prep and install on a piston by piston basis for two reasons. The first is that it takes a shocking amount of time to do this all (I did 4 on the first night, and the other 4 on the second night), and leaving prepped and cleaned pistons to sit for a few days is not ideal…you want to install them when they’re still spotless. The second is that all of the components need to stay together through this section (i.e. cylinder #1 requires piston #1 installed on rod #1 with the rings that were file fit to #1…etc), and that’s way easier to do when you go on a piston by piston basis.
Step 1 is, of course, to clean everything. Thankfully I had another helping hand from Jen on this, which really sped things up. As we both got the hang of things we turned into a well oiled machine (ha…), with her having the exact part I needed – completely clean – at the exact time I needed it. Only a few areas here need to be at that level 3 “cleanroom” clean I mentioned in the earlier post about cleaning. The pin-bore and pin, and the bearings and bearing surfaces (and crank surfaces) need to be spotless. The rest of the piston / ring / rod / etc only need to be level 2 clean, since the oil that hits them will pass through the oil filter before hitting any critical clearance areas of your engine.
Step 2 – Hanging the Piston
Once you’ve cleaned everything, you need to hang your piston. Hanging the piston pretty much means to install it on its rod. It’s very important to do this before you install the rings…the first piston I did I installed the rings first, thinking it would be easier to do without the piston flopping around. While that proved true, I quickly realized that the rings were now covering the pin-bore of the piston, making it impossible to hang. Oops. And be sure to use the right rod to go with the rings you’re going to fit to this piston. Your machine shop will have checked each rod separately for a specific spot on the crank, just like how each set of piston rings is filed to a specific cylinder. Therefore the piston for cylinder #1 must use the rings you filed for cylinder #1, and the rod the machine shop prepped for cylinder #1.
The actual method of hanging the piston varies depending on what type of pin you have. A lot of OEM stuff is press fit, and requires special tools / techniques to properly install. Thankfully, most aftermarket pistons come with what’s called “floating pins”, which only require endless patience and prolific swearing to install properly. Otherwise, it’s fairly simple: Clean and lubricate the piston, install pin lock #1, install the pin through the piston and rod, and then install pin lock #2. In my particular case (and in most cases), the pin locks were spirolocks, which almost completely deserve their reputation for being hell on earth to install.
Spirolocks are not fun to install. By the end of the process, I had a real knack for them…but there were a few at the start that caused real issues, and one in particular took quite a bit of effort to install properly. They’re even more difficult to remove, but hopefully you won’t have to do that like I did…see (much further) below.
Anyways, here’s how to install them. First, stretch them out so they look more like a spring, above. DO NOT over stretch them…about ~1-1.5 inches length is what you’re looking for. Next, get the bottom edge started in the pin bore, so that the end of the spirolock is inside the recess for it in the pin bore. For what it’s worth, I understand that my text here and the pictures are still super confusing, so a quick Youtube tutorial or five is definitely the way to go here. But even with all the Youtube videos, I ran into a few issues, so I’ve tried to address them here.
Now that it’s been started, the idea is that you want to sort of push it into place, bit by bit, going around in a circle. It’s very important that you DO NOT spin the lock itself…rather you push it straight down, working your way around the circle of the pin bore. A lot of people recommend a small flat head for this, but I was a bit worried about scratching the metal or chipping things doing this. This concern proved valid the few times I had to use the screwdriver, but I fully re cleaned any piston that I had to do this with to ensure there were no tiny chips or burrs left. In most cases, I found that I could do it with my thumb if things were well lubed. Unfortunately, there was one specific spot on every piston that was almost impossible to get across, no matter what I tried. Initially this went really badly, and I nearly had to give up…but I managed to get them in, albeit in a pretty ugly fashion that took a lot of tries and bent the spirolock more than I would have liked. In one instance I had to use another pin to fully hammer the spirolock in and then use the flat head to force it into it’s grove and ensure it was seated, so it will probably never ever come back out. But it worked.
As I went, I realized that it was much easier to actually try and grab the spirolock and curve it inwards / twist it through this section. Again, I didn’t spin the spirolock at all…I just tried to curve the next section to be inserted inwards (radially), while also pushing it down (axially), which resulted in a sort of twisting motion.
It took a lot of luck, but I ended up getting the hang of things, and by the second day when I did the other four pistons, it was pretty quick and easy. The one caveat is that you can’t actually breeze through this, because if you do you’ll forget to check each and every piston’s orientation on its rod, and inevitably install one backwards. Sigh. So, it’s very important to check every piston and ensure the piston is pointing the right way relative to the chamfer on the rod’s big end. If you have true flat top pistons with no valve relief, this might not be an issue, but 99% of the time it is. The below picture shows my orientation, and the piston instructions will likely come with pictures specifically trying to prevent this. Take your time, and double check you’ve got it right before installing the second spirolock.
Step 3 – Installing the Rings
Ok, the final step – installing the rings. There are 6 rings per piston in my case, and all of them need to be installed in a certain way or things will go very badly when you start your engine. In the specific order you install them, these six rings are: The oil ring support rail, the oil wiper ring, the top and bottom oil rings, the 2nd ring, and the 1st / top ring. Note that your piston may not have an oil support rail, but mine did – because the pin bore passes through the groove for the oil ring, the oil ring support rail is needed. This is also why I had to hang my pistons first.
Unfortunately, the oil support rail is really hard to install. It’s specifically designed to clamp around the piston very tightly, so it really doesn’t want to stretch around the piston to put it in place. I didn’t have ring expanding pliers, but you’d need to be very careful using them in this case to stop from snapping the oil support rail. Instead, I spiraled the support rail (and all of the other rings) into place – very, very carefully, and with a lot of force and patience to stop from scratching the pistons.
After the oil support rail is installed, you can install the rest of the oil ring pack. The wiper goes first and then the bottom / top rings, which rest in indentations in the wiper. These are all really easy to install, but it’s important to ensure that nothing is in the wrong place – i.e. the top and bottom oil rings are resting in the relief on the oil wiper, and the ends of the oil wiper are nicely butted up against each other.
With the oil control rings installed, the last two things to do are install the second and top ring. Remember that both of them will have dots or some other marking that must go up. Carefully spiral them both into place in their appropriate grooves, being sure not to scratch your piston or snap your ring, and you’re almost done. The last thing to do is to clock your rings. The idea here is that you don’t want any of the ring end gaps overlapping…in fact, you want them to all be as far away as possible. Since I had 5 rings that had gaps worth caring about (the support rail is locked in place with it’s divet and doesn’t really matter), I chose to clock them in an “X” pattern, with the the oil wiper and top ring at the top left of the X, the second ring at the bottom right of the X, the top oil ring at the top right of the X, and the bottom oil ring at the bottom left of the X. This allowed me to clock both “groups” of rings 180 degrees from each other, while still ensuring that there was no real overlap on any of the rings. I also oriented the X such that the four corners were always equally spaced from the pin bores, so that there was never an end gap exactly aligned with the pin (or worse, perpendicular to it where the side loading is highest). At this point, your piston is ready for installation…but this post is long enough already, so I’ll cover the rest in part 2.
