> I'm guessing a leak in the manifold gasket or maybe one of the carb
> gaskets. Does that sound likely? Any other suggestions? Any way I can
> check those gaskets without pulling everything apart?
The classic way of looking for a intake leak is to spray WD40 or carb
cleaner at all of the suspected leak locations. If the engine tone changes,
you've found the leak. WD40 is basically just light machine oil in a spray
can, should be something similar available in NZ.
Some HS6 carbs were fitted with bypass valves, which could cause your
symptoms if the springs were weak or broken, allowing the valve to open at
idle. That would also explain the temperature and choke dependant aspects
you describe. However, I've no idea if your car would have the bypass
valves or not.
Randall
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