Cowl clearance for vertical induction

[jdeas]

Guys, I am installing a 360 vertical induction with Bendix FI
Has anyone else had problems with the clearance of the mixture control arm?
I have tried three different arm offsets. Control on the inside is too close to the air filter element inside the air box (can't cut any deeper into the box)

Control on the outside hits the cowl.

The air box has about 2" clearance on the right but only 3/4 on the left. Does this sound correct? The cowl was originally designed for a carb so is a blister on the cowl needed for the Bendix FI to fit?

 

[LettersFromFlyoverCountry]

You mention cowl clearance but it sounds like your problem is arm interference with the FAB. In this configuration, you have to remake the mounting plate and offset it to the left (as you look at it). Basically by moving the FAB to the left (again, as you're looking at it in the above picture), the recess in the FAB will allow plenty of clearance for the mixture arm.

And also, doing this lines up the front of your FAB with the "snorkel" too.

 

[jdeas]

FAB

I could move the fab about 1/4 but I was concerned about moving the FI throat off center. If having the air filter element off-center to the throat isn't a problem that fixes more than one problem.

 

[LettersFromFlyoverCountry]

You mean the cutout for the FI air intake? You basically get a new piece of .063 and cut it out in the mirror of the old piece. Then you determine how much you want to slide it over and make new cutouts for the studs and for the throat.

I've got some pictures around here -- and some dimensions, too -- around here somewhere. Let me look.

 

[jdeas]

Been there

Already did this once when I tried to slip the whole FAB instead of just the throat. Don't worry about a photo, I know what I need to do now, I just had to come to terms with doing it a third time

Thanks for the input!

 

[Lars]

For what it's worth I made a new top plate (out of chrome moly steel, since the aluminum ones seem to have a reputation for fracturing on O-360 installations) which shifted the airbox to the passenger side as far as I could. Then messed with the lever. Since I'm handy with a TIG torch I cut and rewelded the lever to tuck it in as far as possible. Everything cleared until I fired up the engine and started doing ground runs. I discovered the cable screw had punctured the cowl when it was in the idle cutoff position (wet dog shake). Grrrr... Since the screw had conveniently center-punched the cowl, I drilled it out with a hole saw (1-1/2" maybe?) and made a blister out of glass and filler- yielded another 3/8" or so of clearance at the screw. Got fancy and made it a tear drop shape. It was actually pretty easy. No one even notices it's there unless I point it out, and I have no more clearance issues.

 

[rv699jb]

FAB interference

Another option, is to turn the arm up, instead of down, and then bring the cable in from the front. This will entail making a different cable attachment bracket, and also exchanging your present cable for a longer one. The cable runs along the base of the cylinders, and then makes a 180 degree loop, back towards the mixture control arm in this arrangement. I have a template for making the custom bracket which has been used successfully on three injected RV's out here each having flown now over 1000 hours.....

Jim Baker
RV-6

 

[jdeas]

New FAB top plate

Have some 2024 on the way to re-make the plate. Existing doubler etc should make a good template and can be reused to beef up the struc at the FI holes.
Given a clearance of 1/2 inch on the mixture side and 2" on the other. Moving the whole fab assembly will also keep that 'wet dog' away from the sides of my cowl.

 

[Guy Prevost]

I have the experimental version of the Bendix fuel injection (Silverhawk). To get the FAB to line up with the hole in the cowl, I needed a 1" spacer. This also solves the interference issue with the FAB plate. If you don't need the spacer, you may be able to just slide the FAB to the right. I actually did both.

Because I was painting before flying and the mixture arm was close to the cowl, I also made a cowl blister to insure I would have no contact. You can see the blister here:

 

[JonJay]

You can also get the version of the Servo with Reverse Mixture. The arm then goes up instead of down. You have to bring the fuel inlet into the right side of the Servo and the outlet to the back so it does limit your fuel line routing. This requires some modification of the mounting plate to change the geometry of the mixture cable so it is then inline with the mixture arm.
More than one way to skin this cat.