Deck Plugs, 6/pkg Water Pump Block Off And Filler Neck Kit; Deck Plug Kit; Wall Distortion Reduced; Restrict Water Flow to Cylinder Heads; Upper cylinder wall distortion is greatly reduced when these 3/4" NPT plugs are installed in the water passage holes in the decks of Small Block and 90 V6 Chevy engines Water holes must be tapped before the plugs are screwed in block must also be decked after installation Plugs also restrict water flow to the cylinder heads by reducing size of water...