Before getting back into this, I spent quite a bit of time looking for examples of what other folks had done that I could shamelessly copy, but I really didn't find much that was applicable to my specific configuration. So, I'm going to try to be somewhat detailed in this entry with the hope being that it might help somebody else in the future. A while back, I started this install, thinking I'd knock it out in a couple of hours. Turns out, like so much systems stuff on this airplane, there's a huge difference between a simple R&R job vs. figuring out from scratch what that install should look like. Starting at the lower plugs, I had previously secured the wires aft to the engine mount, and then it got complicated quickly. Basically, there's a lot of stuff in a small area and I need to route the leads in such a way that they don't have any potential to chafe against other stuff, but they still have to be slack enough to account for engine movement. These leads came with the P-mags, and while not as ridiculously long as some slick harnesses, it seemed like some of them were exactly the wrong length; Too long for the most efficient routing, too short for a more circuitous tidy installation. So, after tinkering with this for way too long, I shelved it and moved on to something else. At this point, it was time to dig in and figure this out. My list of considerations for this is as follows: 1. routed to account for engine movement, but prevent chaffing 2. not in the way for ongoing maintenance 3. leads separated from each other (per E-mag to prevent potential inductive mis-firing) 4. neat and tidy I don't like installing adel clamps (does anyone?) but they are undoubtedly the best solution in about 90% of the cases where you need to clamp something like this. However, one issue in this case was the requirement from P-mag that the wires not be run together for more that 6" of their length or run the risk of inductive coupling and misfires or other havoc. They are all going to be in close proximity where they come off the P-mag so I'm already eating into that tolerance. Therefore I decided that it probably wasn't the best idea to run multiple leads through one adel clamp. I ended up going to the car world for a solution and ordered some billet plug separators from amazon. Nothing special about them really, I think you can get them from multiple sources. Couple of cautions if you go this route; you can get them in either plastic or billet aluminum, so make sure you know what you're getting. Also, there really isn't any cushion or chafe protection on these, so take that into consideration. They were a little loose on the P-mag harness which has a wire diameter of about .310 , so I was worried about vibration causing the edges to cut into the insulation. To guard against this, I applied a wrap of fusion tape wherever a lead went through one of these, both to snug them up enough to eliminate relative movement in the support area and to add an additional layer of protection against any chafing. These are basically just two halves that screw together with a flush Allen screw with 10-32 threads. They are drilled in such a way that the threaded portion goes all the way through, but the tip of the screw is flush on the back side. I went to Ace and got some 3/4" long screws, so that when you screw these together over a set or wires, you end up with enough threads sticking out the back that it becomes a stud that you can get a lock nut on. I also took some scrap .040 and .032 aluminum to the shop at work and sheared then bent some simple 90 degree L shaped brackets. Once I got back home, I determined a routing for the leads basically through trial and error, then figured out how to secure them with a combination of brackets, separators and adel clamps. One thing I was trying to do was to keep leads from running under the oil filter so I didn't have to deal with that at every filter change, but I ended up with two under there any way. There really wasn't any other way to do it with the wire lengths as supplied and I suppose two is still better than four. It's hard to get a picture in the mass of stuff criss crossing the back of the engine, so in case it's not clear in the pictures below, here's basically what I've got going on: On the top of the engine, I tried my best to avoid piggy backing off the adel clamps that are butterflied together mid-span on the pushrod tubes to support the fuel injector lines. This was an important consideration for me because on some of the Lycoming engines there is a recurring AD to inspect for cracks/fuel leaks at the brazed fittings at the ends of those lines. Based on that, it just doesn't seem like a good idea to be hanging extra stuff on there. Cessna does exactly that in 3 separate locations on some of their IO360 installations, but I think I'd just rather not do that. At any rate, what I ended up with was a second set of adel clamps coming off the pushrod tubes then an L shaped standoff, then either a billet fitting or an adel clamp, depending on what was needed. In my case, the nylon closeout that allows the upper plug wires to go through the aft baffle wall needed to be modified. I don't remember whether these came with the engine or with the baffle kit, but at any rate, the holes in them were only about .25, so I reamed them out to .310 for the fatter P-mag harness Between hard points, I just installed a zip tie every 6" or so utilizing a short chunk of vinyl tubing I had laying around. Emag says you can use left over manifold pressure hose for this purpose, which feels like it's probably silicone, but I didn't really have much of that left over and I had plenty of vinyl, which is supposed to be good up to 200 degrees or so. I'll keep an eye on it and if it starts to deteriorate I'll do something else here. Where the leads go under the oil filter they have a free span of about 10-12". where they go over that area, I secured them with a billet standoff and an L bracket to a stud on the vacuum pad. Regarding what mag fires which plug, there are a couple ways to go here. Lot's of people have one mag fire top and the other fire bottom plugs. However, there is a standard convention here which is to have each mag fire top on one side and bottom on the other. The reason for the top/bottom arrangement is that historically, the lower plugs were the most prone to fouling, so it made sense to not have all your eggs in one basket so that if the mag that was firing all the top plugs tanked, you had to limp home on all lower spark plugs. With a high energy ignition firing fine wire iridium plugs, I really don't think this applies to my installation, but I also don't see any benefit to bucking industry convention in this instance, so the Left P-mag fires top left / bottom right plugs, while the Right P-mag fires the top right / bottom left plugs. About the only other thing I have to say about this is that the P-mags are a wasted spark system, with towers 1&2 firing as a set and 3&4 firing as a set. This means that you get to choose either of two different tower locations for each plug as long as you stay within the appropriate pair. This comes in handy when you're figuring out how to route everything, as does the fact that P-mags couldn't care less how they're clocked on the engine. When I replace this harness in a few years I'll consider custom wires of a length specific to a different routing that has everything going over the top, but for now I think this will work well and is certainly much neater that a bunch that I;'ve seen with wires running every which way.