no real answer, but encouragement anyway
Bob,
I do not recollect all the details, and certainly don't have pictures. But thought I would try and walk through what I did.
To start with,... you are trying to get a "tube" from the front edge of the cowl,.... to CLOSE but not AT the FAB. While you are getting the tube, you don't want to lose any of that good RAM air that RVs are known for,.. so you don't want to restrict the "tube".
My approach was to:
- first take "initial alignment" from the front of the cowl opening to the FAB,... in my case it was a little off centerline and I had to make a little drift, rather than run straight back. All this really was a look in the front and visualize where the FAB sits in relation to the cowl. Don't sweat being absolutely perfect,.. unless you are absolutely a perfectionist.... for me it was a very short run,.. so I couldn't screw it up too much.
- second jam the foam block on the cowl snorkle to "cut an imprint" of the cowl opening in the foam,..... so then you know the MINIMUM size of the opening you must make,... really need to make it larger,. but this will get you started,.... so .. you can start hollowing out the block. (out in your hands,.. prior to getting it "installed" and it is harder to work and visualize) think little drills, big drills, chisels,.. etc..Remember this is the mold that will define the inside (and outside) of your inlet tube,.. so you don't want lumps and bumps (you may want to mark the back side of the block with the FAB opening... so you know what you are transitioning to.)
- set the block in place - easier said than done,... recommend look for helpful notes from others, I ended up using some epoxy to hold the block in place. good news.. I could move the cowl around and work on the block (file and sand) without a problem bad news... I have some "extra epoxy" inside,.. not visible until cowl removed...
- finish sizing the block - and make sure it does not "narrow down" the "tube from outside to FAB",.. meanwhile providing a "smooth transition" from the snorkle to the tube that will be created...... that is,.. open the block a little more... to allow a few plies of fiberglass to build up inside the foam block,.. when you create the tube. I used a rat-tail file working from the front of the cowl and filing the inside of the block.
- set the fiberglass - I'd recommend some "bi-ax",.. it shapes much easier than plain weave. I stood the cowling on firewall end so the work was "down-hand" and the "tube" was hanging down,... thinking that the tube would have less tendency to collapse than if it was sitting horizontal. Don't sweat the length,... just make sure you have enough "good length" of good glass.... so you can trim back as necessary for the standoff between the "tube" and the "fab". some of the big tongue depressors work well for reaching in and working
- knock off the block,.. and "clean up the tube" inside with final sand/file/filler coat,.. trim,..
good luck,... I had some problems sorting through it... but once I got started in fell in ok,...
p.s. thought you had exceeded the standard time for a good answer on the forum,... so felt I needed to at least give you something,....