Fuel Line from AFP Servo to Flow Divider

[jpharrell]

This post relates to my RV-7A with IO-360, vertical induction and Air Flow Performance fuel injection. I am perplexed trying to figure out how to run a fuel line from the fuel control servo to the flow divider. The fitting on the fuel servo is on the aft side. The flow divider is on top between the #1 and #3 cylinders. I know there is a hole in the lower cylinder baffle for this line to pass but the question is how to get it there from the servo. There are two basic directions one can go (around the left side and around the right side of the sump) and there are many obstacles in the path between the servo and the flow divider. I also have the EI FT-60 "red cube" fuel flow sensor that I have been told should be located somewhere between the servo and the flow divider.

Can anyone give me some guidance how to route this line and where to mount the red cube? Photos would be invaluable.

 

[TS Flightlines]

John---there is no easy answer to your question. I've seen the flow transducer mounted in alot of different locations. But, most builders are running the hose from the servo through the baffle between the cylinder. Some mount the cube down low, some near the flow divider.
Where ever you mount it, try to get as straight a run into and out of the transducer as you can.
Tom

 

[Walt]

I have the same setup, hose runs to the rear then over to the right side where the cube is installed, then up over the intake pipe and up the intercylinder baffle.

 

[BSwayze]

John, I can't tell you much about the routing of the fuel line yet. I'm going to have a vertical induction setup with fuel injection just like yours, so I'm going to have the same situation. I can tell you that most of the "red cubes" that I've looked at have been mounted somewhere other than on the engine. Here's where I put mine: right on the firewall, left of the heater box opening (left, as seen from inside the cabin). I was able to rivet the support bracket that I made to the firewall stiffener angle on one side and to the brake line stiffener on the other side, making for a very sturdy installation. A total of 4 rivets were drilled out to accomplish this, along with 2 new rivets on the top of the bracket. The instructions I received with it were quite adamant about putting it downstream from ALL fuel pumps. So my fuel line that comes out of the engine-driven pump will go into this cube, and it will come out the other side, over to the bottom of the engine to the servo. It will route up from there between cylinders #1 and #3 to the spider. After looking at a lot of setups, that's the one I liked the best. YMMV, as they say.

Hope this helps!

 

[jimgreen]

I forget who I copied on this one. The fuel line exits the rear of my Bendix servo and goes straight back, then up behind the motor and through the rear of the baffle to the spider. The red cube is placed in the vertical portion behind the engine, considered to be a good orientation. The red cube is not rigidly mounted , just restrained with zip ties so no vibration problems.
I only have 80 hours on it but it works perfectly so far.

 

[Rupester]

Same as Jim's ....

My servo-to-spider line routes the same as Jim's above. My flow divider is located on the top R side of the engine, so the line from the servo and red cube penetrates the R rear baffle. The red cube is located about 1/3 of the way down to the servo. The firesleeved fuel lines are stiff enough to support the red cube just fine, and this arrangement provides straight runs into and out of the cube. Works well.

 

[jpharrell]

What I learned so far

Thanks to all who posted suggestions. I also received an email from Don Rivera at AFP with a few photos and the recommendation to:

"come out of the fuel control with a 45 on the hose, make the hose short, maybe 4-6? then connect the red cube, then run the hose on the tops of the intake pipes on the right side and up between the baffle between cylinder 1 and 3 and connect to the purge valve inlet."

I will try to mock this up with some rubber tubing first to see how it fits and get accurate lengths so I can order hoses.

In my continued research though the postings I learned that the red cube used to be sensitive to engine vibration but apparently the design has evolved to where that is no longer an issue.

 

[BSwayze]

In my continued research though the postings I learned that the red cube used to be sensitive to engine vibration but apparently the design has evolved to where that is no longer an issue.

John, this is precisely why I mounted mine on the firewall. I had read some warnings somewhere to avoid mounting it on the engine, inline somewhere where it wasn't sturdily supported, or too near any heat sources, like the exhaust. There seems to be a lot of diverse opinions when it comes to this little device. Any light you could shed on what you have found would be greatly appreciated.

Also, when you get yours finished, post a picture or two, will you? Thanks!