Performance update:
While on my regular cruise today I took note of the criticals and thought I'd pass them along for general info.
I was partially concerned about running an electric fan over the engine driven fan with the thought that it would put an unnecessary drain on the electrics even though I'm running a 60 amp alternator. It seems my doubts were not realized and have come to the conclusion that an electric fan is the better solution.
A brief over view.
The engine is a 69 300HP 350 driving a TH350 trans and an 80's era Nova rearend (ratio as yet unknown)
Electrics are 12v with a 60 amp 3 wire alternator and an HEI ign.
The fan is a 2700 cfm 16" model mounted on a home made shroud and controlled by a 200 on / 185 off sender.
Radiator is a stock 49 GMC with 50/50 anti freeze, a 160 degree thermostat, a 4lb pressure cap and an overflow tank..
**note** The GMC overflow is different than the Chevy as it's tapped into the highest spot on the radiator and not in the gooseneck housing the cap. I'm going to guess once the pressure rises the coolant level enough to reach the high spot it'll just flow unimpeded out the overflow tube. Since I route this overflow to the overflow tank it pulls it back into the radiator upon cool down and I haven't had to add any coolant yet.
There is no provision for the cap to open and dump the coolant out an overflow pipe. If the cap does open theres no place for the coolant to go except perhaps out the gooseneck which it has never done yet.
No heater at this time.
No front bumper apron at this time.
Trans cooling is via a separate trans cooler mounted below and in front of the radiator.
Today the outside temp was a very comfortable 72 and I avg'ed 50 mph on the 1.5 hr cruise. This includes 1 short red light idling, some 65 mph stretching but mostly 40-50 mph cruising.
Other than the amount of time it idled while I loaded up the garbage for the dump run, approx 4-5 minutes, the fan never came on again. The engine temps never got above 195 and avg'ed 180-185 the entire trip. Oil pressure avg'ed 35 psi. So total cooling was via unforced air moving through the radiator.
I have noted on 80-90 degree days the fan does come on more frequently as the engine temp will avg 190-195. Short idling will turn it on as will running 60mph or higher but once the speed is an avg of 55 and under the temps will drop enough to turn the fan off and keep it off until it hits the above instances again. I haven't run it over 10 miles on the interstate as of yet but he highest temp I've seen was around 205-210 and seemed to stabilize at that point.
I'm about ready to stretch it out much further on the interstate and will report any problems then.
So in conclusion it seems the stock radiator will handle a somewhat stock SBC without AC or P/S and maintain proper operating temps with a coolant temperature controlled electric fan and shroud with minimal drain on the electrics.
And how hot does the trans cooler get with no fan forced air? Cool enough to touch but don't hold your hand on it long LOL.
YUMV
Dave
