Air filter box question

I am installing my air box and if you notice the side view of the picture, the fiberglass part slopes up to the intake side. The filter is installed and the aluminum part is setting on the filter and parallel to the bottom part of the fiberglass component. The air intake now is only 1 3/8" tall and the snorkel on the cowling is 2".

Has my fiberglass part deformed or do I need to bend the aluminum part so that it matches the slope of the fiberglass?

No, your box has not deformed. The top of the inlet of the airbox often needs to be higher than the bottom of the Carbeurator / fuel injector. In that gas, the aluminum plate needs to be folded upwards, possibly matching the upwards curve of the fiberglass. In th case of my RV7, I needed to cut the sides of the fiberglass and "un-bend" it to exit straight and level. A heat gun was used to straighten the glass and the resulting "V" shaped cuts on the sides were glassed in.
Confession: I, unfortunately, learned all of this AFTER bending the aluminum up to match the glass.
The bottom of the aluminum plate when mounted to the carb, should be folded up, down , or not at all, to be very slightly above the top of the lower cowling snorkel.

What Carl said.

While you working the air box, go ahead and put in a 0.032" piece of aluminum in the bottom of the box to protect the fiberglass from the filter vibration wearing it away. I also put in 4 pieces of bent aluminum at the base to keep the filter from transforming from a cylinder to a cone. PM me your email and I'll provide photos.

Carl

+1.
I've laid up extra fiberglass here as I started to notice some of the box wearing away where it contacted the filter. an aluminum plate would be better for sure.

Carl Froehlich said:

While you working the air box, go ahead and put in a 0.032" piece of aluminum in the bottom of the box to protect the fiberglass from the filter vibration wearing it away. I also put in 4 pieces of bent aluminum at the base to keep the filter from transforming from a cylinder to a cone. PM me your email and I'll provide photos.

Carl

Click to expand...

I think the instructions for the FAB start the install process of with temporarily clamping the metal top to the carb. adapter plate and then install the bottom cowl.
Adjustments are then made to the FAB top so that the nose aligns with the top of the induction inlet. The best way to do this is fluting heavily with a single flute on each side/flange.

Once the top has been adjusted, the fiberglass bowl is fit to it..... not the other way around.

Wear of the fiberglass bottom is not a problem as long as the filter is not loose (It should always be trapped/restrained between the top and the bottom).
They are reusable filters but they don't last forever and should be replaced periodically because as they age, they shrink.

rvbuilder2002 said:

SNIP

Wear of the fiberglass bottom is not a problem as long as the filter is not loose (It should always be trapped/restrained between the top and the bottom).
They are reusable filters but they don't last forever and should be replaced periodically because as they age, they shrink.

Click to expand...

This has not been my experience - nor that of the builders I know. Still recommend adding the piece of aluminum in the bottom of the air box.

Carl

750 hours and no wear to the bottom of my airbox. I wouldn't recommend fixing a problem until you have it. Adding in an aluminum plate later is easy work if you discover you need it.
I believe most folks who have this wear issue did not fabricate the assembly correctly with the correct amount of pressure on the filter flanges. This is a weak area in the plans and instructions and perhaps some of us just got lucky. Bottom
line, if it is captured and can not move, it won't fret.
My two cents.