Both if you understand the concept of why flowing to fast causes it to run hot when flowing to fast and more at an idle with a manual pump.
If the radiator flows to much you need a re-stricter to slow the flow. If you have radiator that is to small and it restricts the flow it acts as a re- stricter. but you have no control . It is what it is. It is the same principle flowing through the radiator to fast it does not cool or restrict. Look I am not going to argue with you all , You do what you want. The information I am giving you is what Tony at that NASCAR shop showed me and I looked it up and what was in bold print above is what I found. Why don't they run a large diameter top hose with a high flow radiator on any race car. If you flow through the radiator to fast it will not cool. Why ? probably because it does not create coolant pressure in the block.
I have the biggest radiator you could buy from Be-cool in my car. It would have been a lot easier to just clamp a hose on the rad instead of welding that $1000 radiator up where the cap went on and the bungs to eliminate the big hoses. Could have just run a thermostat. Flowing to fast causes cavitation and causes it to run hot because it does not cool as efficient. You believe what ever you want . flowing through the rad to fast reduces block coolant pressure. This is seen more at an idle then at higher RPM's with a manual pump. Either way you look at it if it flows to fast it does not cool the motor due to lack of coolant being retained in the block from resistance from the stat or a 1 inch washer.
The same reason your trans cooler flows from bottom to the top . It keeps the cooler full from pressure of pushing the fluid out the top. if you run it from top to bottom you will create cavitation of the fluid Same deal with the oil cooler. keep the cooler full. I run both and twin electric fans and a CSR electric high flow pump. I run a 1" hose to slow down the flow so the block does not cavitate. The pump will not fill the block to the top at idle unless you re-strict it. The same thing the stat. does when it is open.
If any one with common sense would have read my post. I would not have to explain reducing flow promotes better cooling . It stops cavitation. slowing the flow cools the motor more efficient. No change in what I said . I just tried to explain it to some of you stupid people that have a answer for why nothing works that your not doing.
You all do what ever the hell makes your boat float. I know my car ran cool anywhere. any time, at any speed , at any out side temp. My motor is now 13-1 and rpm's to 9000 all day long if I want and I will run pump gas when I need to and have no worries at all. Some of you could cool your whimp's with a hand held fan.
I only tried to tell the OP what his problem could be. I like hearing some of the foolish stories. Or I wouldn't even try to explain. The friction I get is one of the reasons I will not sell or help members with parts on this site anymore They should all come to you. I don't answer PM's even with the better members that have been to my place.
I frequent other sites. My gold will run out soon like Daves and some others . Then who will be next. Nothing like chasing members that try and help others off of the site. Some of you question things just to cause trouble. Like "Yellow fish with no teeth just gums" Your negatives just chase members away. Your loss not mine. at 64 and all over the states racing everything that has a motor. I may have learned a couple of things. I do not claim to know it all , But what I do know is fact I will stand my ground.
I love factory cars as much as anyone and I build some that way. I have put a lot of money into race cars and learned the hard way. I am just trying to save you all the money I had to spend. Good luck to you on your idle cooling problems. "Yellow fish with no teeth just gums" should have all your answers and parts. he has been doing this for over 60 years. He should have you all covered.
