My Intek (Briggs) has had a problem air cleaner seal from day one and the new engine ate a lot of dirt early on. Briggs tried to foolproof it with fairly detailed instructions and warnings. I am guessing they have had lots of warranty issues with failed compression as the rings work the grit against the cylinder walls. The paper cartridge air cleaner is sponge rubber trimmed to "make" against a flat bottom and raised ridge top perimeter, but it is somewhat awkward to install the air cleaner and feel good about the contact planes. What I do is use a thin white grease tracer film on the sponge rubber so I can "read" the contact areas. Of course to read you gotta clamp down the unit to make impressions, then remove. What happens is that you gain confidence so that you can make a marginal design work. Upon removal you should clearly see line contacts in the thin film grease. The Intek uses two hold down screws with thumb holds and standoffs so one screws down until contact is felt ,at which point a slight "crush" is achieved. IMO aircleaner design and effectiveness is a feature that seems to be greatly improved in the commercial units according to discussions here. I have never owned one.
