Small block radiator size/cooling issues

[nitronut]

I've just swapped a slant six for a 360 small block in a '69 Plymouth Valiant which had factory a/c. I assumed the radiator was heavy duty enough to handle the cooling issues because of the a/c. so I kept the original radiator, fan and shroud from the slant six. I have a March bracket/serpentine belt system on the small block along with a compact sanden a/c unit and power steering. New motor has headers, a mild cam, electric fuel pump, auto trans w/stall converter, rebuilt stock cast iron heads, 600 cfm carb etc. I'm not drag racing it so the fewer ponies were an o.k. compromise for the convenience of ps and a/c.The water pump is a Mopar high performance 8 blade. The radiator measures roughly 23 inches square and has the #2949072 stamped on the top and #38086 stamped directly underneath. The car runs hot. 190-210 degrees in 80 degree weather with a 160 degree thermostat. Is the original slant six radiator too small? I've seen similar radiators on some big blocks and even hemis. I don't know if it needs to be re-cored or replaced with a larger one. I would like to keep the stock look as much as possible. Maybe a re-core with an aux electric fan? Anyone have any thoughts or know what applications this radiator will work with?

 

[Snake]

That temp is fine no worries,what temp does it get to in stop and go.Is you rad a 3 row or 2.210 would not bother me ,I once had a BB chevy that would run a temp of 230 in stop and go never boiled over nothing.heat is horse power.

 

[yellowdartdave]

318/340 A/C radiator, shroud, A/C fan and fan clutch should fix you right up.
Slant 6 rads are made for 225 cubes.

And a seperate tranny cooler helps, esp. with a high stall converter.


Check this one out. 2nd to last picture.

http://www.forabodiesonly.com/mopar/showthread.php?t=93176

 

[jefflock]

You might consider changing the thermostat to 180. This will allow the coolant to stay in the radiator longer to cool.

 

[pettybludart]

I,m with Jefflock on this one,a 180 thermostat and maybe have the rad checked.It may need a recore?I,m running a 2 core rad with 7 blade fan(no shroud)in my 66 Dart with 408/904 with no overheating issues.

 

[Map63Vette]

I'm not entirely sure on this one, but don't most serpentine systems run a reverse rotation fan? Don't know if you are using the stock one or if one came with the serpentine kit, but you might check which way it turns to be sure.

 

[71dustar]

i had cooling issues with my 408 stroker motor. At first i had a 2 core 22x19x3 radiator from summit and a 5 blade clutch fan. I had regular coolant in the radiator and my temps stayed at 230 cruising and would climb farther if i was stopped. I switch coolant to 40% shell glycol coolant (its expensive but we use it in the ferraris and help greatly) 60% distilled water and a bottle of water wetter. the temps then stayed at 210 cruising and would climb to 230 if i was stopped.

Well after being fed up with my engine running hot (grant you the weather is about 110 out here mostly) i switched to a griffin 26x19x3 radiator and a derale twin 12" electric fan setup. Now my engine will stay cool at 195 cruising and will climb to maybe 205 if im stopped. i rarely need to engage the second cooling fan but when i do it brings the temps down quickly.

I would first try different coolant because that is the easiest thing to change.

 

[fishy68]

I'm not entirely sure on this one, but don't most serpentine systems run a reverse rotation fan? Don't know if you are using the stock one or if one came with the serpentine kit, but you might check which way it turns to be sure.

Stock newer stuff runs backwards but the March serpentine system is a direct bolt on replacement for stock pulleys. Got it on my Cuda and it works fine.

Nitronut it's crazy how things work but I've seen guys run 2 core radiators with no shroud and not have overheating problems then another guy might be running a 3 core radiator with a shroud and have overheating problems. Just the luck of the draw I guess. Most of the time in a perf. application anything less than a 3 core radiator will run hot.

Things you can do that should help. Install a 3 or 4 core radiator.

Install a 180 thermostat.

Install Be-Cools water pump disc to help it pump water better and not cavitate.

Install a clutch fan and shroud if you don't already have them.

Run a big auxiliary trans. cooler on the transmission.