Not sure which engine you have. However the stock intake on a 216,235,and a 261 are all heated by the exhaust manifold. No water in the stock intake. Lots of after market 2 and 3 barrel intakes use water to heat. If it is a threaded hole then use a sealer and a set screw to seal it. If it not threaded find out what it is before you put a "goober" fix on it. You will not like the results. Trust me. The intake/exhaust gasket is only under compression at the ports and does distort in between them. So it won't help you with sealing anywhere that is not a port. If the hole is easy to get to you can run a tap in it a little ways and then put in a set screw. That might work just fine.
