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.

The Red Cube

Time: 2 Hours

To get an accurate fuel flow reading on my Dynon system I needed to convert actual fuel flowing to a digital signal. To do this I’m using the “Red Cube” transducer which will take care of this task. My way better half, Tricia, got this for me for Christmas! This girl knows the way to my heart…airplane parts! There are as many ideas as where to mount this as there are primer wars. I decided to follow Jason Beavers location and just put it just to the side of the fuel servo with a short fuel line. From the cube the fuel line will run vertically to the fuel divider “spider”. To start I needed to remove the lower cylinder baffle the AeroSport power installed as well as the oil return line so I could get the baffle out.

I will need to drill a hole in this baffle and place a grommet so the fuel line can pass through it. With the help of Glenn I measured the two lines, one from the servo to the cube and one from the cube to the spider. I’m using a couple aluminum fittings for the mock up and will put in stainless steal fittings when I assemble them.

I ordered the two lines from TSFlightlines, Tom is a great guy and answered every question instantly via email. They arrived just a couple days later and looked great. I really like how he uses a very tight fire sleeve which makes the line look great without a sloppy look. I first measured where I wanted the grommet and drilled the 7/8″ hole. I picked up some high temp grommets from McMaster Carr with the dimensions of 7/8″ for the drilled hole, 5/8″ for the center of the grommet and 1/16″ gap for the thickness. I drilled the hole with the step bit and cleaned up the edges and put the grommet in place. I then reattached the baffle retention bracket on the top of the cylinders after returning the baffle back between the cylinders. Darren at AeroSport showed me a trick to get this back in place. I used some safety wire around the hook. I pulled the wire up through the slot in the bracket and clamped my safety wire pliers on to it. This gave me a lead to pull the hook up with. Then I used a spade drill bit loaded into my adjustable screw driver and pushed down on the bracket while pulling up with the safety wire. Works like a charm!

I grabbed the first line and connected it to the servos elbow. I then screwed in the stainless steel nipple and elbow into the cube and connected it to the line going to the servo.

I then ran the second longer line down through the cylinders and the grommet connecting it to the spider elbow and the cube elbow. To help secure the cube I decided to use some .063″ thick aluminum to make a bracket. The forward spinner support, that I was planning on using, I used a piece of card stock to mock up this bracket. Then I transferred it to the aluminum and cut it out.

I drilled a hole to account for the wiring and match drilled the mounting holes. I don’t have the right length, AN4-17A, bolts so I used longer ones with a set of washers. This allowed me to make sure the bracket is good and I’ll order the correct bolts later.

I connected the hoses to the cube so I could mark the bolt hole from the sump. I took a the end of the bolt and marked it with a red sharpie. I quickly dropped the bolt in its hole and pushed so red sharpie ink would come in contact with the bracket marking the drill spot. After drilling that hole and cleaning the edges I returned the bracket to the cube. I reattached the hoses and bolted the bracket to the sump. Looks great and is very secure, it will look even better with the correct length bolts.

So now I will just need to run the wires and connect them to my Dynon EMS to show my fuel flow when the engine is running.

Baffles #1

Time: 6 Hours

For Lycoming type engines cooling is paramount as they are air cooled. Just scooping air at the front of the engine cowl isn’t enough to keep the engine cooled properly. You need the cool air coming in the cowl to penetrate all the cooling fins of the cylinders. To do this you need to create a positive pressure and direct that pressure around the engines cylinders. To do this you use baffles which direct the air around the engine. The baffles are just a collection of parts that seal up the engine area as to direct the pressurized air. On the top of the baffles will be a rubber seal that will compress against inside of the upper cowl sealing that area. To start I have to separate several individual parts and remove some unwanted areas.

After those parts were all separated, edges cleaned up and deburred I started working on the individual sides of the baffles. The baffles are separated into several sections that all come together to form the entire baffle system. I follow the plans and started with the left after portion. This section is comprised of several parts.

Normally in this area Vans calls for the oil cooler to be mounted on theaft portion of this baffle. However I am using the remote oil cooler mount from so I’m not cutting the normal opening in this area but I’m still putting the bracing to add structure. The aft and side portion are riveted together along the corner but I’m going to wait to rivet them until final assembly when they’re all in place to make it easier to install. Moving forward I primed the surfaces of each piece that would touch each other for now, I will be priming and painting after all the fitting/cutting is done. The baffles get held into place with a series of screws that’s match holes in the engine case. The screws go through the baffles and that area needs to be strengthened so there are doublers in those areas. I riveted them first, then the angle bracing and then worked on the the rear bracing. I used my pneumatic squeezer for most of them but had to get creative on some. I reached into my drawer and grabbed the bucking bar that I had drilled a hole into for my dies. Using the die to cup the rivet head I used my back riveting set to rivet.

After they were riveted I put the left aft side portion in place to see how it fit. I needed to tweak the area around the valve cover to get it to fit as the shape is off just a little. It still needs work but it’s in place for the initial mock-up.

I then worked the left aft section in place. This is a little difficult to say the least as there are a lot of folds, bends and corners to deal with in a tight space. Once in I cleckoed the corners together combining the aft and side parts together.

I repeated the process for the right side aft section which goes in a lot easier.

The forward sides have the same doublers for the screws as the aft sides.

That’s where I quit for the day, progress is the key. Next I will work all four valve cover areas so they fit nice before moving forward.

Inverted Oil Lines

Time: 2 Hours

In between the cowl work I started fabricating the oil lines for the inverted oil system. I’m using Aeroquip fittings and lines that are easily put together. These will have a max pressure rating of 1000 PSI. The process is to cut the line making sure the end is square. Then you slide in the fittings nut which takes a little effort. Then the fitting is inserted into the nut and hose. As you screw the fitting into the nit it draws the fitting into the hose. It also expands the hose locking it in place. After I had one fitting on it attached it to the spot it goes to. On the other end I marked the length and repeated the whole process on that end. You can also see my exhaust pipes installed, or just roughly installed. I did this to make sure I have clearances for all my lines as I build and install them.

More Cowl Work

Time: 4 Hours

Spent the morning today working on the cowl and it’s seams. I wanted to get all my gaps at a 1/16″ to account for the paint. Having this gap will help with the paint chipping when you remove and install the cowl in the future. This is a slow process as I sand a little then put the cowl back in place. Then I remove the cowl and sand some more. I repeated this process several times until I was happy with the gaps. I used a penny as my gauge which is a perfect thickness. I also worked the inner edges of the air inlets and made them all square.

The inside of the upper cowl gets a couple of ram scoops that help direct the airflow. These are preformed and just need to be epoxied in place. I sanded all the areas and the entire scoop so it would be well bonded. Once I had the spots I wanted them I drilled several holes and cleckoed them in place.

I mixed up some epoxy and flox and made the connections.

After these cure I will sand and fill the holes. I will also fill all the edges and make a smooth transition for good airflow. I still have a lot of work on this cowl to get it perfect.