It would be nice to hear back from the OP(BlueRacer69) since we didn't get an answer to the questions in post 6 and 8 before everybody threw in their $.02

There is no clutch fan. A 69 big block Dart had a 18" fixed fan with 1 1/2" pitch to the blades. I've upgraded to a different 18" fan with a 2" pitch to pull more air throu the radiator. Yes I have a fan shroud on it.

I'll politely disagree. I have always run 10-12 initial at idle with out issue

Troy with a Hemi Dart and Barracuda now runs those 3 row high density cores the OP has. Last one from Glen Ray

He has viscous clutch with OE fan. No shroud cause factory hurst S/S didn’t come with them.

No cooling issues with a 528 Siamese bore and 472 regular bore motors. 90 degree So Cal valley weather here surrounded by mountain ranges on to get out and in.


With the items the OP has done so far, I think there needs to be a look at non cooling system issues:

Ignition
Carburation
rust and scale in block
Physical failure: head gasket, head crack, etc
Mechanical: cam lobe flat,

383 cars were often raced and lived hard lives. Do you have any idea the condition of the block?: O-ringed, sleeved, etc. numbers matching?

OE Hemi cars with original/dated motors can have nagging problems like this cause the Hemi parts used to build them are all raced-out. Repaired blocks are typical, large overbores, all kinds of crazy stuff done to them.

Quote

3 row high density cores the OP has. Last one from Glen Ray

there could be a key there, Did the OP's unit come from Glen Ray or elsewhere.
The reason for asking is as previously stated, all cores are not created equally. I know for a fact that Glen Ray uses specific sources and he has helped in resolving more than one over temp BB issues that had NEW 22" cores from other sources.

The one from Glen Ray is the Barracuda he got running recently.

The radiator in the Hemi Dart has been in there for 9 years. 4 row high density core. It was done by a local shop Reseda Radiator . IIRC around $500 back then.


I have an cheap Chinese Champion 22” 4-core in my Barracuda with a stroker 416, 9.7:1 compression, 242@050 solid cam. I made a metal shroud and my MP fan has 1” cut from every blade (dumb champion water neck placement). … I don’t overheat. I bought it because of cost and weight.

I have a "pusher" fan on my 68 Dart. It is a Mr. Gasket 18" I believe. I updated my radiator with a "Champion" aluminum 4 (I think) row. Stock opening in the rad. support. 180 thermostat. Water only with water wetter. 440, 12.5 - 1 pistons. It runs 170 - 190 for me. I usually don't sit in traffic. Alot of the time, I don't even turn the fan on as I'm driving. If I do get in traffic or sitting idling, I flip the switch on and don't worry about it.

Wire it up correctly and you do not have to worry about the original wiring handling the draw of a fan. Use a relay and a hot wire (fused) directly from the battery with a switch or a powered wire from the original harness to the relay activator and you are good to go. The relay activator only draws like 3 amps if I remember correctly. It may be even less.

70HemiGTX, Thank you for that information.

Do you know only have this pusher fan?

Or does is it in addition to a mechanical fan?

I only have the pusher fan. No others.

The temperature on my wife's 440 Six Pack Challenger would slowly creep up on super hot/humid days in prolong stop and go traffic.
Any driving speed over 20mph and the temp would cool down and stay cool.

Had a custom built 4 core 26" Mopar radiator, shroud and FloKooler water pump then swapped to a big Champion aluminum radiator with the same results.

I ended up installing a thin Maradyne low power draw pusher fan in front of the radiator with stock fan still in place.
Ran a simple toggle switch wired to a relay powered from the battery.

Don't need/use it much but it's nice to have if needed and the fan works great.
Car will sit at idle all day at 185 degree with the fan on.

Eventually I would like to wire in a temp sensor to automatically turn the fan on/off and keep the the toggle as a back up.

Moving your trans cooler to another location could also help substantially

I've had the tranny cooler in 3 different locations and completely removed with no change.