Oil Cooler Butterfly Valve

Time: 8 Hours

Now that I have 20+ hours on the engine it is apparent that I will need better control of my oil temps. Even with a good portion covered I was only able to get the temperature up to 185°. The manufacture of the oil cooler mount/shroud, www.showplanes.com has a butterfly valve kit now that will allow you to control how much air you want to go to the oil cooler from 100% to 5% based on their website. So I ordered that kit form them as well as a cable and knob from McFarlane Aviation.

I needed to remove the cooler shroud so I would have access to the baffle. The first step is to mount the outboard pivot block that the valve rod rotates in. I measured half way based on the baffle opening and marked where I needed to drill for the screws. Once one was drilled I could use the other hole as a drill guide.

Once the outboard block was screwed in place I could drill the 3/8” hole for the rod using the block as a drill guide.

I removed the outboard block and opened the 3/8” hole to a 9/16” hole for clearance.

That hole got cleaned up and I installed the block again and slid the rod through the block and hole in the baffle. This allows me to level the rod and place the inboard pivot block so I could drill its screw holes.

Once the rod and pivot blocks were in place I could start on the plate that will act as the shutter. The one that came with the kit wasn’t perfect for my opening so I sue it as a template for one I made out of .032 sheet I had. I used the screw holes as a starting point and made extra measurements to get the size I wanted. I decided to do a double bend of sorts to get the lower half to close as much of the opening as possible.

After I had the shape finalized I added a small piece of aluminum tube that they supplied and a couple of washers on either side of the outboard baffle wall where the rod goes through. These keep the valve centered in the opening and keep it from moving sideways.

The way the valve opens and rotates inward into the fiberglass shroud causes a problem with the inboard lower edge of the sheet hitting the shroud. So rather than trim the cover and loss some of it effectiveness in blocking airflow I decided to modify the shroud a little. I measured and trimmed the shroud so that it wouldn’t interfere with the valve. I then created a mold out of styrofoam covered in packing tape and laid up a couple layers of fiberglass to create a bump out. This will hopefully provide enough clearance for the valve to open freely.

While the fiberglass cured I started the work on where to put the cable and pull knob for the control of the shutter. I decided to put it between the cabin heat and the alternate air pull knobs.

Once I decided that location I worked on the route where the cable would run. The first thing was to work on the firewall pass through.

Once that was finished I ran the cable through the gear tower placing the washer and nut on as I thread it through. Then I used adel clamps to secure the cable as I ran it across the engine mount to the oil cooler. Once I had the cable secured I could measure and cut it to its final size. I adjusted the length so that I had the proper through from open to closed on the valve.

I adjusted the cockpit end so that the knob was lined up correctly and tighten the not to hold it securely. I bought the cable and knob from Mcfarlane Aviation and had the custom knob say “Oil Shutter, Pull On” in the clear anodized.

With the cable all run and it’s function tested all I needed to do was prime and paint the valve, finish the touch up work on the shroud for paint.

I cleaned up the valve and painted it with the same silver as the baffles. I finished up sanding the shroud and primed/painted it as well. Once the paint was dry I started putting all the parts back together. I cut a new piece of the rubber seal that goes on the lip of the shroud to seal it to the baffle as it needed to be slightly longer due to the change in the side I made to clear the valve as it opened.

Now all that’s left is to close everything up and test it in the cold Chicago weather!

First Engine Start

Time: 2 Hours

I spent the morning cleaning up some little tasks for the first engine start. A good once over of the engine area to make sure all items were secure and ready to go. I spent an hour or so going over the starting procedures recommended by Superior and P-Mags. It has been a while since I had started a single engine piston aircraft and wanted to make sure I had all my steps down again. I called my pilot/A&P friends and advised them of the start to come help, watch and advise as needed. Before I knew it we had a small crowd from the neighborhood that popped out to watch the big moment. I followed the steps from AeroSport power on pre-lubing the engine with the lower spark plugs removed. That went smooth and we had oil pressure on the third starter cycle. Plugs back installed and ignitions wires put back in place and we didn’t have any more excuses for delaying. So we pulled the RV out and strapped the tailwheel to my truck. Chocked the main tires and got fire extinguishers on standby. With several iPhones recording I jumped in the RV and ran my checklists for pre start steps. My heart was pounding and I was pretty nervous as I had been waiting for this step for over seven years. Throttle full open, mixture full open, boost pump on for five seconds, boost pump off, mixture cutoff and throttle cracked open slightly. A quick look around and the standard “clear prop” I hit the starter toggle switch. The propellor turned and for 10 seconds or so with no fire. I repeat the boost pump steps and hit the starter again but this time the engine roared to life and the sound of the Vetterman exhaust was AWESOME and just what I dreamed of. Ok head back inside and check the gauges…everything looks good and pressures are stable. The RPM indications were off, a ground wire would be found later to be disconnected from the P-Mag on the left side. I ran through the Mag checks and changed the RPM a little for a few minutes and shut the engine down. You don’t want to do long ground runs on a new engine as you can damage the cylinder walls which need the first five hours or so at high power settings to set the piston rings. No leaks or issues firewall forward and everything worked as it was supposed to.

I can’t describe how nervous but excited I was for this day. It will only be surpassed by the first flight I will do in the next few months. What a day!

Propellor Installed

Time: 2 Hours

Now that we were home with the propellor it was time to get it installed and see how the engine cowl fit. I cut and installed the cowl a long time ago based on measurements from Hartzell and the late Jon Thocker. I asked a couple local pilot/A&P friends to assist me. The process is pretty easy and straight forward. I guessed on what spacing I needed on the spinner backplate which is adjustable with washers and spacers to get the gap between the aft edge of the spinner and forward edge of the cowl.

The spacing on the spinner was a little tight so I adjusted the washers to give a little more clearance. I couldn’t get the lower cowl installed with the cowl lip baffles installed. The material I used is thicker than what Vans supplies and is less flexible. So I removed them and installed the cowl. The fit is ok but still tight and I’ll need to fix that. The spacing on the cowl ring in relation to the spinner was perfect, it has about 3/16” adjustment for future engine sag which allows the engine to slower slightly due to the rubber engine mounts compressing.

What an exciting day! The propellor is installed and all the painstaking work we did to try and get the fit just right based on nothing more than rough measurements paid off. It’s getting close now!

Hartzell Propellor

Time: 0 Hours

Vans emailed early this week that my propellor was finished. I quickly emailed Hartzell and set up a time to pick it up. We had originally planned on staying in the Dayton area to visit the Air Force Museum as well as tour the Hartzell facility. unfortunately due to the virus we were unable to do that so it was just a quick trip down to pick up the propeller and return home. To say we were excited to go done and pick it up was an understatement. This is a huge part of the build and are excited to get it installed.

Baffle Sealing

Time: 4 Hours

One last step that I needed to do on the baffles is to seal up any gaps in the baffles where they meet to engine. The idea is you need to imagine a molecule of air and you want the molecule to cool the engine. That molecule needs to travel past the cooling fins of the cylinders to me the most efficient. If there are other spaces that the molecule can go then that reduces the effectiveness of the cooling properties. So to force as many of those molecules around the fins you need to close any other escape paths for them. One area that had a very large gap was on the right side of the forward baffle. I think it would have been tough to fill it with just RTV so I made a filler strip out of .025″ sheet. Once I had it to the shape I needed I drilled, deburred, primed and painted it to match. Most of the areas that need seal are pretty obvious to see for the not-so-obvious areas I used a light shining up from the underside of the engine to identify them. I used a grey colored RTV sealant, think caulking for environments that get hot and have contact with oils/fuels. It seals well and creates a good bond however can be removed when needed. It’s messy and hard to get it to look good but it is needed to properly cool the engine. I bought a couple large tubes that fit in a caulking gun to make it easier to apply. A couple areas that were too hard to access with the nozzle on the tube so I used a piece of 1/4″ plastic hose that was extra brake line stock attached to the nozzle to help get to those. I was able to use a wet finger to smooth some of the areas but others it was just too tight to get a finger on the seal. They aren’t beautiful but the will accomplish the task. I’m glad I was able to find a color that didn’t stick out like the red RTV that most planes use and would really be an eyesore.

I have a few areas that I want to clean up a little once they cure all the way. In the mean time I went ahead and cleaned all the baffle seals for the top of the baffles and installed them.

Overall I’m happy with how the baffles turned out. I think they will provide good cooling but will have to wait until I’m flying to confirm that.