4 core or 3 core?

[jack'd up]

Will a 3 core rad. cool a big block or do I need a 4 core? Also will an electric fan cool a big block or is the standard fan better?
Thanks, Dennis

[RON WOODGEARD]

Depending on the radiator, a three core will be fine. And on the electric fans,, It depends on the fan, I'm running the flex fan twin electrics, It says up to I think 300 horse.. But there again, it just depends on how well you're cooling system works, and where you live. This all depends on the Big blocks HP, etc.

I am running a slightly warmed over 350. I was living just outside Las Vegas Nevada. I couldn't get the danged thing to cool,, Tried everything you could think of, everything anyone else could think of.... It took a special built 4 core radiator,The twin electrics, and I had to take the Thermostat out... I know this is not normal, but it's the only thing that worked... Cooling was a problem this truck had for about 15 years..
I have had big blocks in other body styles that a double core with a worn out clutch fan worked great....

All you can really do is try it and see what happens..

[71-longbed]

how can you tell the difference between a 3 and 4 core ??

can you tell by the size of the rad holddown ??



thanks

[GMC Jim]

and be sure and use a fan shroud--- and , that the fan shroud matches the approx diameter of the fan

[smitty62]

If you don't run a shroud, a 6-core probably wouldn't cool it--if there was such a thing. A shroud is very important, particularly in slow moving traffic.

[roadking]

why not just put a 4 core in, and not worry about it. i put a 4 core in with my crate motor with along water pump and had plenty of room.

[RON WOODGEARD]

Originally posted by 71-longbed
how can you tell the difference between a 3 and 4 core ??

can you tell by the size of the rad holddown ??



thanks

You can tell a 3 core and a 4 core difference by looking, If you know the looks of the difference, You're best bet is to actually count the cores,, (Number of rows of cooling lines running across the radiator)
I have used the same radiator hold downs for two, three, and finally the 4 core..
Put your fan blades as close to the radiator as safely possible, and yes, if you run a Fan, run a shroud. And only allow about 1/2" between the side of the shroud and fan blades themselves.

[67Fleetsidedream]

I agree with roadking.

[jack'd up]

I have a 3 core in it now. I haven't driven it yet but at idle it overheats. It is a frame off resto and has late model brackets (rev. flow) on it. I guess I need to order a fan shroud and a four core rad. for it.

[GMC Jim]

I would insrall a fan shroud first....and like has been stated in previous replys; the fan should fit the shroud opening....Am using a 3-core radiator with shroud and original equip GM thermo fan. Manual also specifies a 15# radiator pressure cap... (my engine is also a 402.)..........Jim