I have a 70 Chevelle that I am in the process of converting to a Big Block car. I will need to replace the original SB Radiator. I know that I have two options on core size.....20" & 28" 4 core. I have access to a 20" core at a really good price, but am a little concerned about the cooling capacity of this smaller core. This car will have a 454 BB and it's home will be in the south Texas heat. Let me know your thoughts.

For our '72 Lemans Sport, we cool the 455 with a high density 3 core rad. 100 degrees is about as hot as it ever gets here but I never have a cooling problem even then.

You've got plenty of options that will work, but do a search on the Alumitech radiator and don't look back.

With a BBC 28" core for sure,the smaller core is at a good sale price because its good for nothing in a sbc or bbc performance application,dont buy the smaller core.

With that said run a stock shroud,7 blade gm 772 (or repop copy) clutch fan,std fan clutch or h/d clutch esp with AC,w/pump with cast iron impeller thats advertised these days as a 30% better flowing/pumping unit,hi flow 180 deg stat,and std 28" 4 core rad or an alumitech and you will be good to go.

If you back off on 1 or 2 of these things you will likely have cooling issues at times on hot days in traffic but not all the time. Its your choice to do it right the 1st time then try to save a few $ and possibly run into cooling issues down the road with less radiator or an inferior fan/ water pump/etc. Most of the water pumps sold today have inferior pumping stamped steel impellers and thats why i mentioned it. The stock 30-40 pump came from factory with better pumping cast impellers but unfortunately they are usually discarded when the old original castings are rebuilt and the inferior stamped steel ones are installed.

Scott

With a BBC 28" core for sure,the smaller core is at a good sale price because its good for nothing in a sbc or bbc performance application,dont buy the smaller core.

With that said run a stock shroud,7 blade gm 772 (or repop copy) clutch fan,std fan clutch or h/d clutch esp with AC,w/pump with cast iron impeller thats advertised these days as a 30% better flowing/pumping unit,hi flow 180 deg stat,and std 28" 4 core rad or an alumitech and you will be good to go.

If you back off on 1 or 2 of these things you will likely have cooling issues at times on hot days in traffic but not all the time. Its your choice to do it right the 1st time then try to save a few $ and possibly run into cooling issues down the road with less radiator or an inferior fan/ water pump/etc. Most of the water pumps sold today have inferior pumping stamped steel impellers and thats why i mentioned it. The stock 30-40 pump came from factory with better pumping cast impellers but unfortunately they are usually discarded when the old original castings are rebuilt and the inferior stamped steel ones are installed.

Scott

I agree. If you run just the original stock style radiator 28" and CUT OUT the area that doesn't allow air to flow through the new portion of the new radiator, that you just installed. You will not have an issue. I am running that exact set-up, a new stock style 4 core radiator, with a 454 conversion in my former 307 Small block car. 7 blade stock fan 18" w/clutch. No cooling issues what so ever. This is how GM set them up. If you do the same you shouldn't have a problem.