[tomthecomic]

I have a 355 sbc with aluminum heads. What should my max water temp be? It runs 180 or under in 100 temp but sitting or it traffic it can get to 200.

[Rick WI]

That is not a problem for the engine.

[tomthecomic]

how high can it go?

[Rick WI]

A correctly sized and operating cooling system should maintain the setpoint on the thermostat within a few degrees.

For tem rise I'd be concerned if it got into the 220-230 range as the system is building heat and not rejecting it fast enough, soon after the 230 range you'll over heat.

If you are worried about the deck surface of the aluminum heads assuming they are aftermarket they are quite thick (9/16 or so) and can take quite a lot of abuse. Overheating at 240 should not cause warping of the surface like it could with an OEM casting.

[j.d.brown.042964]

You might want to consider adding an aftermarket auxilliary electric cooling fan (puller or pusher) with thermoswitch if room permits, if you really want to keep a tight reign on operating temp.range. I would think that with proper pressurizing in system and all other components in proper working order (as well as sized appropriately for the application) anything within 180-215 would be considered "safe/normal". As others stated it can spike a bit more than that without real damage, but IMHO the 180-215 range would be where you'd want to keep it within. A good clean system with hi-flow pump and thermostat should keep you there, but the addition of auxilliary ("insurance") fan system certainly wouldn't hurt if you can afford it,especially if you do lots of lo-speed stop&go with the AC on in hot weather.-Hope this helps,Jim.