Ok I have an overheating problem on my '74 Nova but it is kind of weird and I have never seen anything like it before (but then again I am pretty young).

While driving around my '74 Nova for a little while in town with the electric fans on it runs @ 180 degrees which is fine, but when I get out in the country (58 mph @ 3000 rpm) with the fans turned off it climbs to 200 degrees really quick then slowly to 210 degrees and stops. Now if I turn the fans on in the country it won't go down, even when I drop down to 2500 rpm or when I get into town with the fans on it stays around 210 degrees. Now if I am @ 180 degrees and I mash the gas it sores up to 220 - 230 degrees or if I am in bumper-to-bumper traffic with the fans on (which isn't to crazy of an idea, overheating in bumper to bumper traffic).

The motor is a standard bore 350 that has had the cylinder walls honed. Now for my cooling system I have the OE clutch fan on the motor, 160 degree thermostat, I believe it is a 4 core radiator, Royal Purple Ice antifreeze additive, I have an overflow reservoir mounted in the OE location, and dual 8in fans that push air through the radiator (powerful enough to pick up a plug from 4 inches off the ground and whip it into my chest leaving a golf ball sized welt). I do have an OE fan shroud but it doesn’t fit. The motor sits to low in the engine bay (it would need to be raised up about an inch or so, I'd also have to notch the sub-frame to get anything other then an OE fuel pump on).

Would raising the motor up and installing the fan shroud fix this? My dad used to drive the car everyday (with a different motor and gears) back in the late 80's before letting it rot in a field and it never overheated on him.

Sounds like the radiator needs repair, or replacing. Or you have a water pump problem (pulley size mismatch or defective impeller).

Big Dave

The radiator I bought new when I rebuilt the car (10 years ago), but the water pump I believe is just an OE piece that was sitting in our garage. I'll deffinitly check it out. Me and my dad were thinking that maybe it was being caused by a lean condition, but the car runs fine and the plugs check out.

i was gonna say water pump cavitation also. Try an alum hi-po water pump. as far as the fans go....make an alum fan shroud that is about an inch deep attached right to the radiator with the fans attached to it. Make sure the shroud cover the whole radiator. An alum. rad. with two 1 inch cores is a better choice to and they are pretty cheap.

Lots of potential problems, the 10 year old raditaor, an OE type pump of unknown quality and 160* thermostat. IMO the 160* are useless. Try running a 195* or at the very minimum a 180*. The 160* is just going to open and stay open, the engine will cool better if the thermostat cycles.

The rad was new (10 years ago) but the car barly has 20,000 on it since then. I was also thinking that maybe the ported OE head cracked cause I seem to be "loseing" coolant as of late (no puddles but it dissapears out of the overfill resivoir and the rad, I don't think it is getting hot enough to boil a 50/50 mix right out of the rad) and it seems to be missing that little something when the long petal is depressed (although after 8 years of driving the same car the same way you kinda get used to it and it doesent really seem special anymore).


When I get some cash I'll get a hi-po alum. water pump and a 180* T-stat. I have a fan shroud but my motor sits too low to use it, I'll see if maybe I could get my hands on some sheetmetal alum. and fab something up using the OE as a template.


Thanks for the suggestion guys.

look at the pic of mine and you'll see what i mean. it works like a charm. use one 16" fan capable of atleast 2000 cfm with minimal amp. draw.

http://inlinethumb41.webshots.com/9896/1100063034044272537S600x600Q85.jpg (http://rides.webshots.com/photo/1100063034044272537nnPhCz)