I searched around, but if there is a good thread let me know and I'll just read that one.... Setup: 350 SBC, supposedly crate, no idea on power Big cam headers 12 psi rad cap E Fan Runs great, cools great. I need an overflow can if I want to make some passes at the track. I'd like something that will suck the coolant back into the radiator. If I fill it to just under the cap hole it might puke some out, if I fill and just cover the fins I don't think any comes out. Would this do the trick? https://www.speedwaymotors.com/15-Inch-Stainless-Steel-Expansion-Tank,7302.html?parentDisplayId=7303 Or: http://www.summitracing.com/parts/RNB-603-100/ http://www.summitracing.com/parts/RNB-603-305/ I don't understand how the vent line would work here, I wouldn't want it to vent from the button..? To recap I like the idea of having an extra 6-10 ounces of coolant, then it would be one less thing to check every other time I drive Mercula. Right now I just have a dangling rubber hose. I know what a coolant catch can is I'm not looking to just run that.