1989 Chris Craft 245 with a 454 and thru hull. I put new exhaust manifolds and risers on it not more than a month ago along with a new thermostat housing and hoses. Both risers are equally cool to the touch after running for extended times. Temp gauge (if accurate) reads about 170 with a 160 stat. I was sitting on the swim platform with the engine idling and just happened to reach down to feel the water coming out of the exhaust ports and I noticed that I could keep my one hand under the port tip and it felt warm, but I couldn't even stand more than 3-4 seconds of keeping my other hand under the starboard tip as it was scalding hot. The only thing I could think of was the idle mixture screws on the carb but they are sealed on the quadrajet. The stream of water seems to come out equally from each tip so I don't think one manifold is getting more water that the other but I could be wrong. Just curious if anyone else has noticed this on their boat and if there was a known reason for it that I am over looking. I guess I could try doing it again with the throttle up a few notches to have the boat run on the primaries rather than the idle circuit to see if the temps even out. If they do I suspect a idle screw needs adjustment. If they don't, then I have no clue.
