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Filter Air Box for O-320 vertical induction

dbaflyer

Well Known Member
Really struggling on the sequence of steps to get to the finish line here. The first thing the instructions talk about is trimming the filter to fit over the accelerator pump. Finally figured out this is not possible until the filter retainer clips are installed.

Next is trimming the length of the air box. You really can't do that until the Mount plate and air box top plate are match drilled together, fixing the fore/aft location of the air box.

So next is aligning the air box top plate, centering it over the mount plate and ensuring it is horizontally aligned with the bottom cowl air inlet. Then matching drilling and installing the retaining clips. Instructions say there are 5 clips but FIG. 5 shows 6. So I'm thinking this is actually step one. However the fore / aft position of the air box top plate is somewhat predicated on ensuring the aft portion of the filter just sits over the drain plug. This also defines where the aft retaining clip needs to be.

Anyone who can simplify this for me gets a cold one next time we meet.

I also can't see how my filter will ever fit uniformly inside the oval hole that is cut in the air box top plate. From what I can tell the retaining clips are positioned on the edges of this oval so that is where the edge of the filter should be. Here I am holding the filter to the rear of the oval and it comes up way short of the front. Flattening the filter just causes alignment issues on the sides. This filter seems too small for this application.

FilterFitting1_zpsiq8irv2i.jpg


It also looks to me like the air box top plate needs to be trimmed to fit over the accelerator pump.

AirboxTopPlateTrimAcceleratorPump_zpsu2skv2ty.jpg
 
I think you're on the right track

I don't remember having to trim for length though. You will trim the top rubber part of the filter so it nests against the accelerator pump. Don't cut all the way through. Cover edges w proseal. Yes I think you will have to install the clips -5- first to insure the filter stats in position so you can determine where to trim for the pump.
 
Also

It probably won't fit perfectly uniformly in the hole. Mine has a small gap of 1/8" varying width around the diameter of the hole. I tried to make the filter housing airtight so as to maintaining positive pressure through the filter element.

You should not have to squeeze or otherwise force the filter element into position. You could trim part of the plate by the accelerator pump or perhaps move the plate a little. Hope this helps.
 
You want the filter to be inside the cut-out on the outer piece. The filter should actually sit proud of that metal piece by a small amount. The pressure from bolting down the inner/upper plate should slightly compress the small rubber ridge on the filter to help seal. The small angles are rivetted in to the outer plate to hold the filter firmly centered in that position.

Larry
 
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