Can anyone tell me what the difference between a 1" thick core on a radiator, and one that is 1.25". I ordered online a radiator with a 1.25" core thickness just like the one I am replacing, but was sent one with a 1" core thickness. I sent it back, and reordered with the same result. Before I send this one back, what are your thoughts on this? I live in Florida, so my concern is sitting in traffic on a hot August day with the a/c running. The car is a 1994 Chevy Lumina 3.1.
The 1" core radiator has less cooling capacity because the tubes where the coolant runs in the radiator are 1" wide. The cooling fins between the tubes are also 1" long. Where the 1-1/4" core radiator has tubes that are 1-1/4" wide so more coolant can pass thru and the cooling fins are longer and thus more surface area to remove the heat faster.
You can install a thicker core radiator in a vehicle that originally had a thinner core radiator. But installing a thinner core radiator in a vehicle that had a thicker core radiator can cause overheating problems.
Yes, find another source that has the correct radiator. Try Autozone, etc., you may pay a bit more but you can check it before you buy it. I had to go to a thicker one years ago when I moved from Ohio to Texas.