My stock rad core size is 28 1/4 X 17 1/4. The closest i get to that in the summit catalog is 26X 18 1/4 and thats their biggest rad for GM. From tank to tank its 31X19 which would make my rad bigger than their biggest, which doesnt make sense because I had a 6 cyl car. So, do i just get the biggest one and hope it can cool my 400 sbc enough? I know a lot of you guys recommend these radiators so what did you get? Also do these rads take just an autozone rad cap? One more thing the guy said these are universal rads so they come within a 1/2 inch, mine doesnt even come close to within a 1/2 inch

wantedrodinco, I have a Summit universal radiator in my 64 SS with a 355. I think it was the 26 x 19, with 1 in. tubes. It cools much better than the stock 3 row that was in it, I run a 180 t-stat and engine temp cruising is usually around 190 even on the hottest days (95+). Had to get creative with install though, being a universal radiator. I plan on adding an electric fan soon. Summit measures overall dimensions, their largest is 27 3/8 x 19 pn# SUM380328, core dim are 24 3/8 x 18 3/4 x 2 1/4.
They are 2 rows w/1 in. tubes so they have much more surface area to cool down the coolant.

I also have one. It is the smallest they make and it cools great. I only have a 283 now, but the stock overheated all the time. Also, I ran most of the summer WITHOUT a fan (including a lot of 100+ degree daily bumper to bumper commutes) without overheating (couple close calls, though). I have no doubt that it could cool a big block with a good fan (have a deralle 16" now). If I switch it on with the temp over 200, it will be hovering at my thermostat temp (160) in less than 5 minutes.

Did you buy it yet?

See this post..

http://www.chevelles.com/forum/ultimatebb.php?ubb=get_topic;f=4;t=021395