Offy Dual Quad Small Hole 9.15K viewsApril 8, 2017 0 mike@lasby.net April 8, 2017 0 Comments I purchased an Offy dual-quad manifold for my ’62 Olds 394, and it has a small hole/port on the underside of the manifold. What is this for? Will it need to be plugged to avoid a vacuum leak? Thanks! 1 Answer ActiveVotedNewestOldest 0 OFFYEXPERT169 Posted April 22, 2017 0 Comments This hole does not need to be plugged it is a heat tube for an integral choke. Hope this helps. You are viewing 1 out of 1 answers, click here to view all answers. Register or Login Offenhauser Sales Corp, 5300 Alhambra Avenue, Los Angeles, CA 90032 Phone: (323) 225-1307