Junction blocks are used to relocate nozzles hoses when intake ports are some distance apart or several castings are used. They can be used on either blown or unblown applications, also for water injector hookups and vacuum lines. Another common use of the junction block is the tunnel-port manifold with the use of a blower type hat.

A fuel shut off valve can be installed in the inlet fitting of the junction block, positioning it close to the nozzle hoses, to insure quicker starts and cleaner shut downs.