Fuel Line Question

Hey All,

Has anyone had any trouble with fuel line routing on the RV-7A. My issue is the fuel servo to the fuel pump. The flex line comes very close to the exhaust pipe. Does anyone have any pics of how they routed theirs? Also, could a person use a solid line from the fuel pump to the fuel servo, similar to the solid line from the prop gov. to the front of the engine?

Thanks

Jonathan,
My FWF kit for a 0-320 came with a heat shield that clamps to the exhaust and protects the fuel line.

Phil
N3938C
40 hours

Jonathan:

I had initial concers also but I found that by holding the line away from the exhaust while tightening the servo fitting, the line tightened up and is held away from the hot parts. Try tightening the fittings and see if that works.

Jekyll
7A
IO-360
Precision servo

Is this for a vertical or horizontal draft engine? I am struggling with the hose-to-exhaust clearance on my IO-360-M1B (horizontal draft, forward induction). There's not a lot of room between the oil sump and the pipes, and the mixture bellcrank spoils the hose routing I'd like to use. It may turn out that I just have to put heat shields on all the nearby exhaust pipes, and try to clamp the hose as far away as I can.

mcb

<<The flex line comes very close to the exhaust pipe.... could a person use a solid line from the fuel pump to the fuel servo, similar to the solid line from the prop gov. to the front of the engine?>>

Jonathan, I assume the servo is a Bendix. Route a firesleeved flex line along the port side above the wing on the sump, much like the hard oil line runs along the starboard side. A 45 fitting on the end of the line will couple to the port side of the servo well clear of the mixture arm. You can secure the line front and rear with two adels on the 1/4" sump bolts. If you need to run wiring in the same area, attach a mounting plate to the sump bolts and space the fuel line and wiring well apart and parallel using adels on the plate.



<<I had initial concers also but I found that by holding the line away from the exhaust while tightening the servo fitting, the line tightened up and is held away from the hot parts. >>

Jekyll, dependence on flare fitting friction might not be a good idea.

Safety wire on snout

Dan

Thanks for the picture. I didn't see anything on safety wiring the mounting bolts the horizontal induction snout in the instructions but I see you did it. I think it is a great ideal and will "borrow" it so I can copy. My only gripe is the darn bolts are just a pain to take out. Guess it is fitting to say, if it's worth having, it's worth the work.

Webb

For what it's worth, here's a couple photos of how I routed this hose:





Unlike Dan's nice looking installation, my mixture control uses the Van's bellcrank assembly, so I couldn't bring the hose all the way up and over the "wing" of the oil sump like he did. I clamped the hose to the #4 intake tube in two places, which holds it up and away from the exhaust and keeps it clear of the mixture linkage too. The photos don't show it very well, but I ended up with an inch of clearance between the hose and engine mount tube, an inch or more between the hose and exhaust heat shields, and 3/4" between the hose and mixture bellcrank when it's in the idle cutoff (worst case) position.

After thinking about it some more, I wonder if it's worth replacing these normal (200F) adel clamps with the high temp (400F) variety. The plans don't make a big deal of it, so maybe the garden variety clamps are okay in this application? I hope so, it took me all afternoon to put them in! (@#$% pipes getting in the way!)

cheers,
mcb

The engine is a vertical draft. I'll try to post a picture of the installation (well, trouble with installation), but I can't seem to get the firesleeved hose to route in any decent fashion! Too many things in the way, like engine mount, exhaust pipe, throttle or mix braket, etc...

Is a solid line from the engine mounted fuel pump to the "carb thingy" a big mistake, or is it acceptable? Any one have this set-up?