Setting up Summit overflow. questions.

If you put it on the top, it will only work as an overflow - no matter how much you "pre-fill" it. If you put it on the bottom, it will work as a "reservoir" and exchange coolant with heating and cooling like the factory one does.

im with Adam. i would think the thing comes with a hose and fitting so that you can make it work as a reservoir (as Adam put it) using the top fitting. it probably does not, though.

but i dont like that way, even if you can do it, cuz if you dont have a nice tight seal, it wont refill the rad as necessary.

the pressure/vac in the system overcomes gravity. no biggie. if you filled the reservior all the way and drove it, coolant would gush out. the reservoir level is dynamic (changes).

so what im trying to say is that the bottom connection is the best way to go, on all fronts, as Adam said.