Cooling issues

I run my system at 207*F with a 1973 radiator. This is a 195 hi-flow stat that appears to actually be a 200 to 205. That sets the minimum cooling system temperature.
The thermostic clutch on the fan, sets the max to 207*F, by cycling as may be required. Around 30 mph, there is enough ram air thru the rad that the fan goes into freewheel mode and costs me nothing in terms of power or fuel useage.
I have a seven blade direct-drive fan, that I use for diagnostics. I wouldn't spin that bugger to max rpm either.
IMO,Your fan is adequate, but it does need to be in a shroud to be effective at low speed and idle.
A lower temp thermostat will only delay the inevitable on a prone to overheating engine, and only for a few minutes.
Eliminating the heater core, if you don't need it, is IMO a good thing, as it eliminates the coolant going round and round inside the pump. I did that too, and furthermore severely restricted the flow in the bypass hose. This helps my alloy heads warm up in a hurry. Then the stat opens and I'm gone. It can still take 2 to 4 minutes, at hiway speed for the rest of the engine to warm up. I can always feel the engine surge ahead 2 to 4 mph when it comes on-line. Now it's GO-TIME!

One test you can do, engine not running, is to run water thru the fins from a regular garden hose with no attachment.Put it up tight and the water should run right thru the rad without any back splash.
A second test is to check the difference in temp between the water returning to the rad, compared to that entering the pump. I like to see 30 degrees there.
Make sure your engine has enough idle timing; I like 14* minimum make sure the all-in is not excessive for your gas; on a fresh iron headed engine,I like 34 at no sooner than 3400. After you get to know her, you can sneak up on it.

both those pumps are el cheapo junk
if you want to cool you press off the impeller and spot weld a disc on the back side
no cavitation, no air bubbles, works at higher rpm, more flow, etc
or you can buy pumps with that done or a solid impeller

that anti-cav plate really works

The first ones I saw/ used were done by TMS propane in Santa Fe Springs
he had the die for the plates and did the pressing and task as a one man band
then he licensed the idea to my neighbor the late) Richard Bauman of Speed-O-Motive
then Idea spread to many other boutique pump builders
damn right it works

He said damn,lol
It made a huge difference to my combo. Knowing that now, I would never again build a performance engine without one. At the time I bought my Milodon they were more than triple of a local jobber pump, and with the money exchange, brokerage fees, and shipping, it hurt a lot. But it was worth it, and that pump is still going, since 2004, so I quit thinking about it a long time ago.

i used a stock 22" radiator from a 1070 340 with clutch fan and shroud with a milidon high output waterpump and never overheated even in traffic when 90 degrees outside . Changed to a champion rad last year when the 426 stroker went in figured it might make a bit more heat . a good radiator is cheap insurance

At your temps I wouldn’t worry. I will start paying attention to my gauge over 200, I continually scan it at 205 and I stare at it at 210. Over 210 I start doing things to bring it down. It only gets that hot on hot days on the highway because of the rear gear I run and it only got that hot twice during drag week and it was HOT! If I slow down the temps drop right back down.

The first thing is to move your fan back away from the radiator allowing the fan to pull more air thru over more area of the radiator and 2nd definitely add a shroud. I had the exact same issues a while back when I could not keep my temp lower than 200 and I did just what I mentioned here and as of today my temp hardly never goes above 190 and this is on a 90 degree Hot and humid day in traffic....Usually runs anywhere from 170 - 185 with a 180 degree thermostat.

I want to add a shroud to my '67 Barracuda. It has the stock fan and no shroud. Will a 68 A body shroud work on my set up. Non clutch fan.

383Scampman said:

O.k. , start with a clean cooling system . Next , install a high flow water pump (A/C) . Then a highflow thermostat@ 160-180* . OEM 18" fan and shroud . Make sure your pulleys are the same diameter . Use 50/50 coolant with w ater wetter . At 190-200* you are almost there . another 5-10* cooler and your golden . La engines were designed to run cooler .

Click to expand...

The stock thermostat at least on a '70 318 is 195 degrees, and it appears according to the service manual that the others are 190. Everything he has there looks like my original stock 318 stuff. I wouldn't run a thermostat cooler than 180, its going to do just about nothing in this situation anyway. Nobody should need water wetter anyway.

The A/C pumps actually are the 6-blade ones also, not the 8-blades.

190-200 degrees indicates there is no issue present. Especially if the thermostat is unknown. It may have a stock 190 in there in which case it functions perfectly.

If you want it to run cooler, you need a bigger radiator and a shroud and check the thermostat you have.

my 340 never overheated even at 90degrees plus in traffic , stock rad clutch fab shroud and 50/50 distilled water anti freeze ran 6 years never a problem , rad still looks new inside . used stock water pump and 190 thermostat

I would get a clutch fan. here's my 67 273, correct rad, etc, with aftermarket shroud they say doesn't fit....but it does...could use a longer stemmed clutch, but works better than the old 4 blade.

nothing is going to work unless the block , heater and radiator are clean