You said you can see the lower hose sucking in when you rev it. Is there a spring in the lower hose to keep it from going flat? Flow restriction on the inlet side can cause lots of trouble. Make sure your rad to radiator yoke is sealed or has min gaps, also no gaps in the fan shroud to radiator interface.
Travis..
I use only well sprung hoses, top and bottom on my radiator, with excellent result! I tried the molded hoses once, with piss poor results, dropped them quick, and never looked back.
Ironically enough, the factory shroud for my 1965 22" 2524984 radiators has big, heavy gauge stamped steel brackets which held the shroud about 1/4" away from the radiator frame and tanks all around. I used foam weatherstripping and aluminum foil tape to seal that gap on the old setup.
Having recently replaced my venerable 3 row 2524984s with an OER MB2384A (4 row, 22" radiator, meant for the 426 Hemi according to OER and Classic Industries) I saw that its made for them by US Radiator, as can be seen below:
Alas, as expected, I COULDN'T BOLT THE OLD SHROUD BRACKETS to the new, after market radiator. They did the usual cheap-arse trick of making a flat flange for a flat sheet aluminum electric fan shroud. They also ****** up the hole pattern for the yoke, just like certain other aluminum vendors do.
BUT despite these little sins, the thing COOLS WONDERFULLY. IFF my damned Latest Brat can be restrained long enough for me to type a decent article, I will. As it is: I made an aerodynamically superior bracket from 1/16" thick, 2"^2 aluminum angle which permitted me to bring the shroud closer to the radiator than the old heavy stamped steel ones do, and yes, the shroud directs the air drawn by my 18" 7 blade 2.25" Mopar clutch fan very nicely. My coolant temperature has YET to exceed 200 F and only RARELY gets that warm, with 180 F, the thermostat rating be FAR MORE the NORM for this engine. I verified this with ambient pavement temperature around 140 F this week. As always, THE decisive factors are coolant and air FLOW. While the pusher fan only rarely kicks on, it does at 200F for brief cycles when at traffic signals.
Anything which hampers coolant flow (including air, which cools the radiator) unduly will cost in performance, fuel, lubricant and engine parts. So, KEEP THOSE RADIATOR HOSES OPEN BY ALL MEANS!
