Was that temp reading taken at the usual location?
Somebody said advance.And thats a very good point. If your engine isnt running enough advance under cruise conditions, it wont be making the cruise power that it could be making with the correct amount of advance. This will then require more throttle input, which will burn more fuel than it needs to. More fuel means more heat created. Which means more work for the cooling system. Meanwhile the late ignition means that perhaps not all the fuel has enough time to burn in the chamber. Some of it may continue to burn in the exhaust system, creating more heat. Some of this exhaust heat may spend time trapped under the hood.And if you dont have a fresh-air system, this hot air will find its way back into and through the carb. So you can see a vicious circle developing here.
So, if you dont have a vacuum advance dizzy, or cold air induction,you can expect problems. Under light throttle cruising at 3300, the engine will probably want 50 to 60 degrees of timing.This will require experimentation on your part. My mild 360 with aluminum heads is quite happy with 45* to 50* at 2150@62mph(O/D). Your fuel economy will increase as well, so its worth it to figure this out for someone who does spend significant time on the hi-way.
Your results may vary.
BTW,, 220* is a good number, as long as it never climbs much higher.I'd be more concerned with oil temps. Most oils will handle about 250*. After that,somewhere around 270, they start to smoke and boil of some constituents, which makes them done.
My 360 has been running 220 for years and years.
