Gdads, it looks to be the boss that the throttle linkage pivot post screws into in your picture. Mine uses the rear one. I’m thinking I’ll just plug it with a 5/16 bolt and sealant. High heat RTV silicone you think?
Doug
RTV silicone sealant will work fine. I'd suggest Permatex 22071 Water Pump Thermostat Housing RTV Silicone Gasket Maker as it's designed to work in the high temp coolant/engine environment.
Just a suggestion, but a machine screw as shown in the picture above may sit flush better (and seal better) than a bolt that might not have threads all the way flush to the underside of the head.
