The stubstack is designed to only work effectively with K&N Filtercharger™ elements and 360™ custom air cleaner assemblies
The K&N Stubstack reduces turbulence, improves metering accuracy. Increases the airflow by reducing restriction. Straightens and speeds up air-flow.
The K&N Stubstack is designed to increase the airflow of carburetors, by decreasing the restriction around the choke horn. The stubstack fits inside the air cleaner housing and slides snugly down over the choke horn.
Install holding nut finger tight and use Loctite or 3M to seal. When installed on some models, there may be a slight gap at the base, however this is normal and will not affect the performance of the stubstack.
Due to space limitations between the choke horn and some air cleaner baseplates, the stubstack has two thin spots in the casting.
These will sometimes crack or chip slightly, but does not affect the performance. Because carburetor castings vary, the stubstack will not fit all carburetors.
Check the list numbers for proper application. On some carburetors that are listed, it may be necessary to alter certain areas on the stubstack. The polyurethane material is easily filed and sanded.
Air Filter Application
The stubstack is designed to only work effectively with K&N Filtercharger™ elements and360™ custom air cleaner assemblies. If the stubstack is installed in an improper housing, the performance may actually drop! The minimum height above the stack needs to be at least 1-1/2″ for proper operation. See http://www.knfilters.com/racing/stubstacks.htm for compatible K&N custom assemblies.