Fuel hoses
I decided I’m going to learn to make my own fuel hoses.
Step 1: Figure out the routing and proper length.
Step 2: Wrap the hose with tape where the cut line is and cut very slowly and carefully with a dremel cutoff wheel.
Step 3: Cleanup any stray strands.
Step 4: Lube everything up real good with some oil. The inside of the hose, the fitting, the threads, etc. Liberally.
Step 5: Push the hose into the sleeve all the way until it bottoms out on the base of the threads.
Step 6: Mark the hose at the base of the sleeve to keep an eye on “push out” while the fitting is threaded in.
Step 7: Holding the hose in the sleeve, push and thread the fitting in.
Step 8: Tighten the fitting against the sleeve and ensure the hose wasn’t pushed out more than 1/32″.
Step 9: Pressure test to 1.5 times rated pressure.
This takes a little bit of practice but is pretty cool to be able to do. Some things that I learned along the way: Use liberal lubrication of the whole assembly. At first I wasn’t using enough oil and things got really tight really fast when trying to tighten the fitting all the way. More oil makes all the difference. I’m using Marvel Mystery Oil. It is what was handy. Also, use the cutoff wheel very slowly. If you try to cut too aggressively with the wheel, it will fray the hose just enough to make it a real pain.
I decided to put a 45 degree fitting on the mechanical fuel pump inlet so that the hose would clear the bottom of the prop governor housing on the accessory case. Others have just used a straight fitting there and allowed the hose to rest against the accessory case, but that didn’t give me any warm fuzzies. I did have to drop the bottom part of the fuel pump in order to thread the 45 deg. fitting into the pump housing. I’m much happier with the inlet setup now. All of these hoses that I’m making are Aeroquip 701 hose with straight fittings. The firesleeve that works well on the -6 fuel hose is -10 firesleeve. This is all just fabrication and mock-up right now. Later I’ll come back to all of this stuff and put clamps on the firesleeve and finalize all the fittings. Anything that doesn’t have a dot of inspection lacquer isn’t done.
I put a 45 degree steel fitting on the carburetor inlet and clocked it just so. Ahhh… entry of the dreaded fuel flow transducer. The pictures tell the story. I’ve spent a tremendous amount of time trying to figure out where/how I was going to plumb this thing. If you’re looking for a perfect, per spec, installation of the flowscan sensor, this isn’t it. But I have very reliable information on a flying example of an installation exactly like this that works just fine. Even if there is a tiny bit of error (because of that 90 degree turn on the outlet), I’m ok with that. Ok, enough of defending my installation. I tinkered with the orientation of all this for quite some time before committing to making the hoses. I’m just going to use an adel clamp to hold the flowscan in place on the engine mount. It is important that all of these hoses have some bends in them and aren’t just straight shots. This is harder than you might think sometimes. The bends are important because the engine is going to be jumping around a bit in relation to the fixed engine mount. The hose bends allow for that movement.
I painted the filtered airbox and that is drying. The carb heat on the airbox is all fabricated and ready for complete airbox assembly. A shop setup note: We’ve been thinking about how we’re going to be setting up our hangar. We decided we’re going to use some cheap plastic storage cabinets to store a bunch of stuff in. We actually found a place to put one in the garage. It now houses all of the parts trays that I’ve always used for all the small hardware. As we get further along and I buy more stuff to have on hand, the tray count has been steadily increasing. I’m so excited about this cabinet because I don’t have all this stuff stacked around the garage any more. We should have done this long ago.
