7 hours.
Apparently, 7 hours is enough time to royally screw up a cylinder baffle. Case in point:
The #4 cylinder baffle holds the oil cooler on the aft section of the baffle. The way this is supposed to work is that the baffle is made largely of 4 pieces: There’s the part that connects to the #4 cylinder head, the part that holds the oil cooler, the part that covers the inboard part of the crankcase, and the stiffener that holds parts 1 and 2 together and gives it some beef so the oil cooler doesn’t rip the baffle apart in all the vibration. The plans call out a distance of 3/8″ from the outboard edge of the baffle where it joins parts 1 and 2. Fun fact: If you stick to this dimension, you don’t get enough room between the drill-through holes of the oil cooler doubler and the angle on part 1, which means you can’t install platenuts. Part 4 has pre-drilled holes which supposedly line up with the holes in the oil cooler doubler. The plans then say “keep the oil cooler as high as possible for maximum efficiency.” Well, that’s neat and all, but if you do that, you get out of alignment with the predrilled holes, and everything’s a mess.
Another important safety tip is to leave cutting out the big rectangular hole for the oil cooler airflow until AFTER the whole mess is drilled. Long story short, I wound up making a huge mess, with holes drilled way outside acceptable parameters for edge distance, a rectangular opening about 1/4″ off from where it should be, and a generally bad day. So I have to order new parts from Van’s and call it a lesson. Also, the plans say to follow the callouts on drawing OP-27A. I don’t have that one, I have drawing OP-27, which is probably the same thing, but I have to check.
So after setting that aside, I went on to see if I couldn’t screw up the #3 cylinder baffle as well. Lo and behold I did not.
This one clecoed together nicely. IN the above photo, you can see the flange for the cabin heat intake. A little piece of screen goes between this and the baffle to keep the grasshoppers out of your cabin heat muff attached to the exhaust pipes.
Here are the two sections of the #3 baffle in an intermediate state of completion. Notice on the lower right, the cutout looks a lot like a Lycoming valve cover. The two doublers there are where it screws to the cylinder heads. One thing you have to do to get these things to fit right is to trim away the excess gasket squeezing out from under the valve covers.
Another shot of the #3 aft section. You can see the bug screen sandwiched between the flange and the baffle, as well as the tab that mounts to the crankcase. Bit of fun, that. In order to get to this part with a screwdriver, you have to dismount the oil fill tube from the engine. Nothing else will work, not even my miniature ratched screwdriver. That’s fine, I just have to remember to safety-wire the oil tube again before I run the engine.
A test fitting. This is a pain. Install, figure out where the baffle rubs on the crankcase, uninstall, grind down baffle, repeat.
From the back. See how deeply buried that mounting tab is? It’s hard to see, but there’s a piece of black PVC tape covering the hole for the oil fill tube.
I also started messing around with the center mount bracket, which requires a little bit of moving the injector lines around to keep clear. This steadies the middle of the baffle in back and connects both #3 and #4 baffles together at the center.
Next is to continue on with the #1 baffle, whichever one connects to the one I just built, because I can’t do squat on the other side until I get the new parts for #4.