Originally I had this 90-degree fitting on the top of the oil cooler, because I thought that a 45-degree fitting would push the existing hose too far back where it would hit the firewall. You can also see here that there's much better engine mount clearance with the oil cooler mounted vertically along the side like this (better than it was when I had it raised and tilted in). It's not a big deal either way, but you can see that the old relief cut I made in the oil cooler rear flange was no longer really necessary.
And here's the most significant improvement as I see it. Originally I had a 3/8" stainless steel tube running pretty much in this same spot. The difference is that the tube ran back to the baffle joint and didn't tie directly into the oil cooler. The inboard side of the oil cooler was allowed to flex despite the baffle itself being braced. And of course the tube broke at the crimped end, predictably. This setup is an 1/8" thick aluminum angle that theoretically doesn't have any stress concentrations like the crimped stainless tubing did. When I installed this angle brace I thought it might impede flow through the oil cooler since it's kind of a big ugly drag-inducing structure right there in the slipstream -- but I've found through about 8 hours of flying in 100-degree ground OAT conditions that the oil cooler is working just fine. You have to put your faith in the cowl/baffles being a pressure vessel, not a wind tunnel. As long as there's positive pressure in the "plenum" then air is gonna flow through the oil cooler.
At this point I'm convinced that a brace like this is absolutely necessary to preserve the integrity of the baffles. If you don't brace your oil cooler somehow, you're just asking for your baffles to self-destruct in that area. If you have fuel injection like I do, you'll probably be resigned to installing the brace like I did...but if you have a carb'd setup, you don't have the flow divider and distribution lines to deal with -- so you can run the brace inboard to the case bolts instead. Parallel valve engines don't have these nice baffle mounting bosses on the top of the heads like the angle valve engines do. Anyway, do what you gotta do to brace your oil cooler like this and you won't regret it! Tom Prokop passed on some advice from Jerry Scott...you should be able to move the plane around by holding the oil cooler. Sound advice.
At the front end the brace fastens to the front baffle mounting boss on cylinder #2.
At the rear it bolts to a chunk of 1/8" angle that is in turn bolted through the baffle to the oil cooler mounting structure. This braces the oil cooler directly...which is a huge improvement over the old system.
Here you can see one result of the way I rigged the brace, which is that I still have wide-open access to the top spark plug on cylinder #4. I was gonna be willing to remove and replace the brace if I had to, but it worked out great, and I won't have to touch the brace when removing/replacing the spark plugs.
Similar to what I had before, but slightly simpler, I made a little "continuity wedge" to make the baffle seal installation trivial here. I wedged a piece of fiberglass into the triangular gap and then laid up a mixture of epoxy and flox to fill and seal it. It adds rigidity as well. I was slightly worried about the reaction of intense heat coming off the engine and the epoxy, but it has held up fine after many operations on several very hot days.
Today I swapped out the 90 for a 45-degree fitting here on the top of the oil cooler.
I'm a bit more comfortable with the hose being run like this. I may have a slightly shorter hose made so it doesn't have to "S" at all, but we'll see.
Ok, now to the coil wiring thing. I got some photos of that setup today as well. Here you can see the fast-on connectors on the coils. If the wires aren't supported behind the baffle wall, strain can be imparted on the wires where they get crimped in the connectors.
So here's the little doohickey I built. It's just a piece of .040 that got bolted to the rear baffle wall mounting bracket. I put a couple of -2 adel clamps on the bracket, and the wires are totally secure here. This all moves in unison when the engine shakes, so no strain could possibly be felt at the fast-on connectors.
Here's another view. The red wrap is self-adhesive silicone wrapping tape. At the ends of the RG400 coax I soldered 16AWG wire (white wires), which run through the adel clamp on the engine mount. From there, I gave each of them a generous strain relief loop before passing through the adel clamps on the baffle bracket. When the engine shakes, these large loops are what absorb that motion. (No, the wires on the right side don't pass under something even though it looks that way...that's a piece of black heat shrink I used to denote which coil the wires go to.)
Here's another tweak I made today. Cylinder #1 & #3 CHTs are almost perfectly even. Not the case for #2 & #4. Cylinder #4 has always run about 35-40 degrees cooler than cylinder #2. Today I trimmed about 1/2" from the "temperature riser" (a.k.a. "air dam") in front of #2. Here you can see I just wedged some scrap sheet behind the air dam so that I could just use a cutoff wheel without worrying about it cutting into the cylinder's cooling fins. (I can tell you now, after flying, that this trim made about 5 degrees of difference...I'm going to keep trimming it iteratively until the CHTs are as even as possible.)
The other day, I was flying alone and I hopped into the right seat to fly from there for a while. I don't know what prompted me to try it, but despite my headset being plugged into the pilot's jacks, I pressed the copilot's PTT (push-to-talk) switch just for kicks. Nothing happened. I felt behind it and could feel one wire had broken loose. Today I pulled the switch and found that one of the solder terminals had snapped off.
It's another 20:20 hindsight situation, where I didn't provide enough strain relief. Here you can see the replacement switch, and how I used double heat shrink wrapping to provide additional strain relief.
After buttoning everything back up and preflighting the rest of the plane, I went flying. I wanted to top off the tanks for a flight to work tomorrow, and I figured since the sun was setting I could get a few night landings in. The sunset was really pretty tonight. I messed with my camera's exposure and managed to get some cool shots of the sky.
Here I was on my way from French Valley up to Corona.
Looking south over the hills toward the Orange County coast.
The moon was out, although it didn't come out as clearly here as I wanted it to.
Here I was on descent for Corona...kind of fuzzy, but you get the picture.
I've got six hours of night flying in 14D so far. I go up about once or twice a month and do the three full-stop landings to stay current. Tonight I did that and topped off for my flight to Santa Monica for work tomorrow.