Cooling ???

[Gimmie1965]

Hey everyone have a radiator question. Have a 65 gmc with the 305 v6. Getting ready to be able to pull a 5th wheel camper. Down to installing a bbc. It's a stock 77 454. Have everything gathered and hoping to get started this weekend. Biggest question is has anyone done this and kept the stock radiator. It has a 3 core in it now. If I install a shroud along with what I think is a stock 6 blade fan and clutch. Maybe install a lower temp tstat. What's your thoughts

[sstock]

Shroud would definitely help. I never could understand why GMC didnt use shrouds with their V6 engines, maybe because it has such a huge cooling capacity, mine takes north of 8 gallons to fill.

[vin63]

I think you might end up fighting cooling issues if you don't go with a higher capacity radiator (4-core) when you install that Big Block. I ran the same pair of electric fans on my 4-core radiator with a shroud that had no problem keeping a small block Chevy cool. When I built and installed my 462 Pontiac, it was a different story - it would quickly go to 210+ idling in traffic. I had to modify my shroud with a couple of pressure release vents and run a pair of H.O. Derale shrouded fans inset into the radiator shroud to increase the airflow efficiency over the fins. It now stays in the 180-190 range.

[Captainfab]

I agree on going with either a 4 row core copper/brass radiator or a 2 row core aluminum radiator. Both with a good shroud and fan(s).

[Gimmie1965]

That's what I'm afraid of. Especially pulling a 33ft 5th wheel threw the mountains here in Colorado. What radiator did you go with. I've found a aluminium 4 core on Amazon for 340. Comes with a shroud. fan and temp switch w/ wiring. Didn't really want a nice shinny pretty radiator but I really can't afford a direct replacement from U.S. radiator or champion.

[T Herder]

Years ago I had a leaking radiator and took it in for repair. Told my guy I regularly run at a GCVW of 17-18,000 lbs. and sometimes it runs hot. He guaranteed he'd make me happy. He built me a 5 pass radiator using the stock tanks. No matter how I run, light or heavy, flatland or 21% grades in 4 low heavy with 102 F outside temp, the temp gauge runs at constant 190 degrees.
My GMC, 1965 ¾ ton 4X4, 305E, fuel injected, stock fan, no shroud. I run John Deere antifreeze in all my trucks, need it for all the diesel rigs.
Butch

[LVPhotos]

Won't DOT have an issue with you when the stock gross is less than what your pulling? Hope you got good brakes.

[Captainfab]

I hope your truck is either a 3/4 ton or better yet a 1 ton, with disc brakes up front and preferably hydroboost brakes.

Originally Posted by Gimmie1965

That's what I'm afraid of. Especially pulling a 33ft 5th wheel threw the mountains here in Colorado. What radiator did you go with. I've found a aluminium 4 core on Amazon for 340. Comes with a shroud. fan and temp switch w/ wiring. Didn't really want a nice shinny pretty radiator but I really can't afford a direct replacement from U.S. radiator or champion.