Heater Muff

Time: 1 Hour

On the right two exhaust pipes there gets a heater muff or shroud that creates hot air for a heat source. This shroud goes around the pipes and heats air that goes inside the shroud via a scat hose coming from the aft section of the engine baffles. Then the air leaves the shroud via a section of scat hose to the heater valve on the firewall. This came with the exhaust system from Vetterman and is pretty straight forward to install. You can see in the photos why I had to move the exhaust hangers to make room for the scat hose connections.

Exhaust Support Brackets

Time: 2 Hours

Another task I wanted to get finished to help with wire/hose routings was the support brackets for the Vetterman 4 pipe exhaust. It’s pretty simple as they give you most of the parts. They consist of two shaped brackets that hold two pipes together, the left side and right side. You have to construct a strap to tie the two brackets together. Then the two brackets get a support brace that is made up of stainless tubes that have flattened ends on them for bolt holes. These tubes get connected together with some flexible hose to account for vibration. So I measured where the two brackets would end up keeping equal distance from the cooling ramp. There is no exact spot for these so I just went with what worked based on my oil lines. Once I had them where I wanted them I made a mark so I could return them. I removed them and marked for the 1/4″ hole that needed to be drilled and drilled a smaller pilot hole. I returned them to the pipes and clamped a piece of angle that I would use for the strapping across the two brackets. With that in place I used a Sharpie to mark through the holes I drilled on to the angle.

Once those were marked I drilled all the parts to a 1/4″ hole and cleaned all the edges. I trimmed the angle to look better and be the correct length. From here I just shortened the tubes so that they would be the correct length between the brackets and the adel clamps I put on the engine mounts accounting for the required 1/4″ gap needed between the ends of the tubes. I put all the parts together and bolted them in place. I tightened the left bracket bolt a little too much and bent the lower bracket a little so I’ll remove it and straighten it out later. For now they are secure and I can continue to run wires and hoses. One thing I have found with the firewall forward stuff and doing things a little different than the stock setup is that you need to be flexible. I had planned on the support bracket arms to be located in one spot but found out that they will interfere with the heater muff that will be located on the right had exhaust pipes. So I redid my measurements and made some modifications to the support arms to change things up. Once I was happy o removed all the steal parts and cleaned them up for a coating of high temp paint. Once that was dry I returned all the parts and tightened things down. This arrangement gives a little more support and remains clear of the heater muff and allows more room for the scat tubing that will later go here.

Fuel Servo Brackets

Time: 4 Hours

Due to my specific engine that incorporates the Superior cold air sump as well as the full inverted oil system the stock brackets and connections to the fuel servo won’t work. These are the connections for the throttle as well as the fuel mixture servo arms. This is a common problem for builders using this engine sump. I already had the two cables that connect the throttle quadrant to the fuel servo and just needed to fabricate some type of brackets. There are plenty of builders that have done this with just as many different connections fabricated. I saw one style at OshKosh this year and wanted to do something similar. I started by laying under my engine looking up and eyeballing where the cable would end up. Then I made some cardboard templates to get a rough idea. I ended up making several versions from the templates in aluminum before I ended on one that I was happy with. Once I was happy with the aluminum ones I repeated the shape and bends in some .050 steal sheet from Aircraft Spruce. These were then primed and painted with high temp engine paint. The paint I ended up using was Moeller Honda marine engine paint. It almost matched perfectly with my engine paint.

After installing them and making the adjustments I safety wired them.

I’m happy with how these fit and securely hold the cables. Another fun fabrication complete!

Alternate Air Cable

Time: 1 Hour

In the case of a rough running engine due to the air filter getting clogged and restricting the air flow there is an alternate air door on the side of the snorkel. This door can be opened to allow unfiltered air to supply the fuel injection system so the engine continues to operate normally. I had run the cable in the cockpit some time ago and fabricated the door hole per the plans. Today I measure and cut the cable and attached it to the door. I also secured the cable with adell clamps to the oil return line from the forward cylinder head. It operates smoothly when opening and is not intended to be closed again in the air as the cable has to much slack to push it closed without bending. The idea is to get you back in the ground safely they return the door to the closed position after you remedy the cause of the clogged filter.

Fuel Pump Cooling Shroud

Time: 1 Hour

Back when I installed the engine on the engine mount I installed a cooling shroud on the engine driven fuel pump. This has a flange that allows for a 1″ duct to direct cool air to keep the pump cooler. Now that the baffles are almost done I needed to create a take off of the baffle to allow pressurized air from the inside of the baffles to be used for this cooling. I bought a 1″ flange and marked out where it would best fit so that the duct hose would not interfere with other cables. I used the my 1 1/8″ hole punch to create the hole. Then I laid out three rivet holes and match drilled them to the baffle. Using the bucking bar and gun I made quick work of attaching the flange to the baffle. I measured and cut the duct hose and trial fit it to see how it looked. I will secure the hose once the baffles are painted and back in place for good.