I'm surprised that I haven't seen anyone else with this question. I have a fairly stock 427, the thing is that when the summer temps get near 90, the temp just keeps going up if I get caught in traffic. I have a 4 core stock radiator with an electric fan and shroud. I had the radiator cleaned and was told that it was in great shape and I shouldn't have any problem overheating. It hasn't overheated, but it isn't summer yet either. My friend has a Chevelle big block, he has bought an new aluminum radiator with electric fan and shroud, he spent $600.00 and his still tries to get hot in traffic. The only thing that I can think that is different between my car now and 1970 is the difference in the gas. I plan to try ethanol free gas with an octane booster to see how that might help. Any other ideas out there ???

 

BB can be hard to keep cool on hot days with stop/go traffic. Combos of larger multi core radiators, more blades on fan, correct shroud/fan geometry, secondary electric fan on front of radiator have been used with some success in those high weather temp days with slow movement of vehicle

What I have not seen much mention on is a EWP (electric water pump). I have used one now for 20+ years and 90+K mi on another car I have (Gen 2 LT1 383) and in 115 degree Vegas heat temps do stay manageable. They do get hotter to about 210 vs the 185 normally but no hotter

Assuming all your current efforts of good, large enough, radiator, fan/shroud and electric fan....might be something to consider

EWP put out a constant flow regardless of engine RPM which is higher than what the flow rate would be running a mechanical at idle/low speeds

https://www.meziere.com/Products/Coo....aspx?ext=.pdf

https://www.meziere.com/Products/Coo...ow-55-GPM.aspx

 

A couple of things you didn't mention. What temperature thermostat are you running? If you have a 180, try a 192. If a 192, try a 180.
Check your ignition timing, too far retarded will make an engine run hotter. Also, make sure your vacuum advance is hooked up to manifold vacuum, NOT the ported vacuum off the carb like what was used (changed to) back in the 1970's smog era.
Advancing the timing at idle makes an engine run cooler. Remember the decades old instructions "disconnect vacuum advance before setting base timing"? That's because vacuum advance used to be connected to manifold vacuum.
You're likely going to need to adjust your curb idle down once you connect the vacuum advance to the right port (if it isn't already).

 

try a mechanical fan

 

Thanks for that, someone had mentioned that before, but I had dismissed it. I kept thinking that " it didn't overheat before". It looks like it's time to update my thinking and use what is available to me....... Middle Tennessee can get several weeks of 90 + temperatures in July and August.

 

Thanks for the timing advice. It does seem like I can remember un-plugging the vacuum hose to set the timing and having manifold pressure there. I am currently running off metered vacuum, I'll re-set the timing , you be on the mark with that advice. What are your thoughts on the gasoline ???

 

It has been suggested to try a flex fan, but they have been known to come apart with high RPM, I'm not sure that I want to risk that yet, thanks

 

I would run a clutch fan .Thats what came stock on those cars .along with a 180 thermostat .

 

I was running a clutch fan, but had a worse problem than now. It wasn't loose or anything, it had a good clutch, it was working properly, just wasn't pulling enough air to keep it cool. They seem to need more air now. ( I wonder if it's global warming ????) ha ha

 

I still have the fiberglass flex fan that was on the 396/375 when I bought it in 72. the owners before me did nothing but race the car, so the fan seen nothing but maximum rpm. I have a heavy duty stainless Derale flex fan on my SB. the fan is rated to 10K rpm . my stroker is red lined at 6200 .
everyone complains about the RIVOTS. the original 4 blade fan of the 50s was put together with rivots
get a 6 blade derale flex fan and DO NOT WORRY