Van Window Foam Seal

Using the cardboard box the porthole came in you can trace a pattern using the inner portion of the trim ring or aluminum inner frame of the window whichever you are more comfortable with should yield approx the same template. 

Once your pattern is drawn out you'll cut it from the cardboard box. Determine where on the Van you will install your porthole window. Check the interior for possible obstructions. The Porthole comes with a reversible mounting ring so can go straight to the exterior metal of the van using the 1/8" or you can flip it if you have interior walls to a 1-1/2" depth. If you need to use the 1-1/2" depth you may need to create a spacer often times a 1" thick ply would that's cut into a ring to place behind the wall to fill the gap between outer sheet metal and interior wall.

Before cutting always double-check the pattern size make sure it's the inner portion of the trim ring and only the extruded aluminum thick frame can go through holes and can always be trimmed larger if needed not so easy to make them smaller. 

Once your hole is cut apply tape on foam seal to the back side of the porthole window start and end at the bottom so the gap of foam is on the bottom to prevent leakage. 

If you do not have two people you will want to tape the window in place otherwise one person holds the porthole from the outside while the other screws on the interior clamp ring (mounting ring) much like a tire you will tighten a little at a time top, bottom, left, right ensuring an even seal. 

That's about it for a Van Porthole Window install. 

Here is a printable installation sheet. 

Van Porthole Window Installation