Baffles #2

Time: 10 Hours

Before I could move to the next step I needed to get all four sections that go around the chrome valve covers to fit just right. They come with the basic Lycoming shape but need to be trimmed to fit. There are two holes on each section so I decided on a plan of attack. I worked one section at a time and repeated the process for the rest. I slid the baffle down until the screw holes, which were off a little, were equal on both sides. Then using a red Sharpie I traced the valve cover. I removed the baffle and sanded down until touching the red Sharpie line using my drum sanding bit in the Dremel. I returned the baffle and checked the fit, repeating this process until I had the holes matching the holes in the engine and a 1/16″ reveal around the valve cover.

I cleaned and deburred the forward and aft top baffle bracket. These use the engine case bolts to hold them in place. I attached them, temporarily and not torqued yet, so that I can get all the work done before painting them.

The plans now call for you to work the forward inlet baffles. I started with the right side and cleckoed/match drilled all the holes.

In the right side I need to account the constant speed propellor oil line. This line runs from the front of the engine case to the propeller governor in the aft section. I need to drill a 1″ hole that will get a rubber grommet later. I used the drill press and step bit to drill through both parts at the same time.

I took all the parts apart and deburred the holes/edges. I prepped and primed the lower strip of the air dam that gets riveted now. Once the primer was dry I riveted it in place and reclecko’d all the parts back together. I took the baffle assembly and put in place which took a couple of try’s as the lower bracket needed trimming to fit around the cylinder.

from this point you have to start working the forward inlet ramps of the baffles to match and fit the lower part of your engine cowling. The ramps have an angle to them which is short for bringing the ramp up to the cowl lip. The goal is to bring the ramp up to the lip leaving a 1/16 inch gap. Here you can see the gap that you start with, it’s quite large.

So the process that I used was to remove the cowl, remove the screws holding the baffle in place, remove the baffle, slightly bend the ramp upward, return the baffle to the engine, screw it in place, return the cowl and check the gap. This process is time-consuming but necessary so that I don’t bend it too much. I started with the right side first and get the process multiple times to get it right.

You can see that last photo the inboard edge of the ramp is perfect however the outboard edge still has a gap. This is due to the angle of the inlet on the fiberglass. To solve that issue Vans has you mark a point at the where the inboard section touches the inlet, the tangent, and draw a line between it and a point on the outboard aft corner of the ramp. This line now becomes a reference line at which you can bend the ramp to bring up the outboard edge to the cowl lip. I used a few boards and clamps to make this bend. I did this a few times to get the bend right.

Now that the ramp is in position I need to work on the side baffle that meets up to that ramp. This also needs to be brought up to within a 1/16 inch gap of the vertical portion of the cowl lip. Again it’s the same process of mark, remove everything, remove some material and then return to see how it looks.

A lot of material has to be removed from these battles, including the forward edge of the ramp. I marked the edge of the fiberglass onto the ramp to give me a start line. This also gives me a reference point to create the bottom bend on the side baffle that will hold and support the ramp.

I then marked out a tab on the side baffle that would get bent 90° to create the support for the ramp.

Once I was happy with my layout I made the cuts and bent the tab using some boards and my rivet gun with the flush head using low power.

I fine tuned it with my hand seamer. I returned it in place to check the fit followed by trimming the forward edge of the ramp. I used a clamp to hold the corner together and returned the cowl to see how it looked.

Next up the left side ramp which houses the air filter and “snorkel” attaching the fuel/air servo.

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