RV-9A Lycoming IO-320 vertical induction fuel line location

Trying to finish up my firewall work before the IO-320 D1A get here. I am unsure were the IO-320 fuel line should penetrate the firewall.

The plans call out for a location near the starter relay, Vans however told me that was for the horizontal induction. Vans suggested near the where the gascolator would have gone. I was worried about hose length and routing around the exhaust and the fact the gascolator provides a location and direction translation to the penetration also. What have other people done with the IO-320D1A?

Sure would be a nice to have a list of the actual deviations or steps to the install the IO-320 vertical induction that Vans sells as some people seem to have struggled with it. Does not appear to be many builder sites that actually use the FI 320.

Welcome Steve,
I have the IO-320 and I used the stock gascolator location. Good location to get a short hose to the mechanical fuel pump.

Keep in mind that the high pressure electric pump is located between the fuel selector and the firewall. Also, I elected to put the "red cube" fuel flow transducer between the electric pump and the firewall. Seems to work well in that location

Thanks for the reply's, I looked at the Lycoming drawing for the D series and it does look like that route from the gascolator could work.

ah red cube, another variable. I had planned to it suspended it in the line between the engine pump and throttle body as that seems to be the preferred engineering location. Seems like any 4" or so fuel hose as to be custom to go between the red cube and throttle body".

MarkW did you put another 90 on the FWF side or let the hose make the bend? I know to use Steel when doing this.

Steve

Hey Steve,

I have the exact same engine, with the AvStar fuel servo. Here's a few pictures showing my install. I kept the red cube inside, right up against the firewall.

I really struggled with the routing of the fuel lines, but I finally came up with a setup that works well. The key is to route the fuel "out" line to the back of the servo. I used a 45-degree fitting, clocked at about 2 o'clock. Fuel "in" goes around the outside of throttle linkage, which leaves plenty of clearance between it and the exhaust. The "out" line penetrates the baffling above the upper left engine mount bolt, and then to the back of the fuel distribution spider. I used Adel clamps to tie the in & out lines together in back of the fuel servo. It was frustrating because the AvStar servo came with very little documentation, the website is useless, and I had to call the company to make sure it was OK to plumb the out line to the back of the servo. When you remove the block-off plug and the fitting, you can see that the passages connect.

My mixture arm stuck out a bit, so I made a bubble on the cowling for clearance. I also made a thicker (1/8") FAB plate with more offset.

Good luck with your install!

I used a straight fitting on the fwf side. That left a nice gentle hose curve to the pump. I installed my red cube between the servo and spider. I also used the front servo outlet fitting.

rightrudder said:

... Here's a few pictures showing my install. I kept the red cube inside, right up against the firewall...

Click to expand...

I know you're still in construction but I have some comments/concerns with your setup. Your fuel lines interconnecting the pump, filter, red cube, etc are short and straight. This can be a bad thing if the components themselves are locked down to the airframe. I see cushion clamps in some areas which is good, but if you lock down that red cube with bolts I fear you will have issues. Though it seems like tying the components to the airframe makes for a rigid structure, heat and vibration can cause a bunch or relative movement between these components, and short, straight rigid lines then become a structural element trying to resist this movement. It doesnt take very long for a flare to break when put in this situation. I'm also concerned with the firewall penetration - that fitting is mounted to a diaphragm and is subject to quite a bit of fore and aft movement. Any fore and aft movement is going to react poorly with that short tube and 90 degree fitting buildup.

Again, I know it's still in work, but it might be worth a review of AC 43.13 and T.O 1-1A-8 to see if your plan is endorsed.

Finally, not a safety issue, but I though the FF transmitters required some length of straight tube going in and out. Not sure its going to like the two 90's if thats the case.

Hi Michael,

Points well taken. The cube and the fuel filter sit on pads of medium-density foam, so that'll allow some give. Maybe a short piece of braided hose between the firewall fitting and the cube would be in order. Since I took the picture, I've replaced the firewall fitting with a steel piece.

My understanding is that it's preferable to have a straight run into the cube, but not absolutely necessary. I realize that accuracy may suffer a bit, and I'm OK with that.

Hose after the cube would work, but so would a hard line with a few bends in it. You could replace the "out" 90 on the cube with a straight (180) fitting, and snake a hardline around to another 180 at the firewall (or re clock the 90 you have). This would give you at least two 90 degree bends in the tube and enough length to allow plenty of flexibility to deal with a drumming firewall.

Alternately, turn the Cube 90 degrees and connect it directly to the outlet of the pump with a staight fitting and the shortest piece of SS or 5052 tube you can make. Do a 45 (or a 180 if it will fit) on the outlet and snake a hardline up to the firewall fitting (again, a 180 would be best).

Anyway, you have a very sano installation and mine are just suggestions from the peanut gallery.

Thank you for your input and suggestions, Michael. So many safety issues are created with faults in the fuel system, and I want mine to be as bulletproof as possible.

After thinking on it a bit, I might leave the red cube as-is in terms of fittings and location, but turn the 90-degree firewall fitting to 9 o'clock and bend up a piece of tubing more or less in the shape of a question mark to connect the two. I've got a lot of room to the left to make a decently large-radius loop.

I've used the "question mark" bend in the past to solve a similar issue. Mine was FWF and was made of SS hardline. It worked well. I'd imagine your application would work out too.

Done! Thank you for helping me build a safer airplane.

There is at least 3/8" of clearance between the red cube and the firewall, so the cube won't be subject to vibration from direct contact.

is it worth moving firewall fuel penetration?

I built my 9A for a carb and installed a gascoator in the traditional Vans location on the right lower part of the firewall.

I've decided to switch to a Bendix fuel injection servo. It will be vertical induction in place of the carb on my O-320.

I've removed the gascolator and need to decide where my firewall fuel feedthrough will be. I can see two options:

1. Feed the fuel through where the gascolator was
2. Use the Vans location for the horizontal induction IO-320. This spot is much closer to the center and a bit higher. It is about 4.5 inches below the firewall recess on the right side.

#2 has some advantages I think, including maybe a shorter hose to the engine driven pump, and not having to run aluminum line behind the right side rudder pedals.

Of course the minor disadvantage is that I have to patch up the gascolator hole.

I can't see why vertical or horizontal induction would make a difference, since the hose goes from the firewall feedthrough to the mechanical pump. The pump should be in the same place in either case.

Thanks for any opinions!