i`ll be watching THIS thread close...lmao...(cooling issues myself)

 

My old setup: 540 cubes, all iron block and heads. Hydraulic roller cam, two 1050 King Demons, 14:71 blower,8:5-1, headers,timing at 36 total. Electric water pump (aerospace Tech), custom aluminum radiator, 20 inch puller electric fan.I built a custom shroud for the radiator, so that the air was forced through the radiator.Also used the chemical "water wetter" in my coolant,which was 80% antifreeze. Helps to dissipate the heat. No overheat issues at all,and this was an iron headed engine with a supercharger. Car ran about 190-200 under all conditions. Car also had AC. In answer to the intial question- "Why do some cars run hot", IMO, its about moving ample amounts of water and air to cool the engine. Move enough of both, and there are generally no issues. High volume water pumps, large radiators (aluminum preferably),fully shrouded radiators, and adequate fan(s) for airflow all combine to make it happen.

 

Just my thoughts - No shroud, airflow recirculates. Bigger engine, makes more heat than the OE rad was designed to remove. Thinner cylinder walls conducting more heat.

There are theories about the difference between alum & Cu/brass radiators, IMO, alum dispense heat better, but have yet to prove personally.

Pump speed, flow inside, air flow across, fin count per inch, width of rows themselves, the list is endless.

I would like to read responses also. My 454/TH400 Dually with A/C on yesterday w/93*F was 225*F. with 180* Hi-Flow. I bought the truck new and dealer stated if it doesn't puke, it's normal. Truck does not cool down idling. Everything is new, except engine. Cu/brass rad, haven't changed to alum yet.

 

Add water wetter to the mix.... You'll drop roughly 10 degrees IMO with no other changes. Its a cheap way to experiment.

 

327, .030 over, stock 2 row rad., Full shroud, 180 stat., stock w.p., would run 180 w/ o.a.t. below about 70 F, once it got above that it would climb to 210-220. On really hot days I would have to shut it down because it seemed like it was going to keep climbing. Speed didn't matter. I had the radiator rodded. The guy that did it said it was only about 30% plugged and he didn't think at that amount it would make much of a difference. It now runs 180 to 70 F, and above that goes to 195 and stays there regardless if I'm idling or doing 70 mph with or without the AC running.

 

I would love to list out all the potential causes, but if I got 6,452 on paper someone would ask hey why didn't you get #6,453 you dum Okie?

So instead I'll answer your question...
Why do some cars run hot?
Because they are making more heat than they are exchanging to atmosphere if you define "hot" as overheating.
Or the relationship between heat rejection to air and heat input from work is such that they cannot have an inlet water temp approach to ambient temp that is "normal".

"Approach" is the term heat exchanger people use to state the effectiveness of an exchanger when BTU input equals heat exchange capabilities.
On my junk standard is 20* approach for gas cooling, and I think 80* approach on water sections, based on 100*F ambient.

This is how you determine if the engine is the problem or the heat exchanger is the problem. Temp rise across the engine, and heat loss across the exchanger. Too much rise across engine with acceptable inlet temp = engine problem.
Too little drop across radiator with adequate airflow = cooling problem. Mushrooms from there.

 

Getting interesting quickly.
Let's try to avoid restating the obvious too much, we all know this stuff

Why does Dave's 327 heat up, and my 383 does not? Even with the old original stock 2 row rad and NO SHROUD, my 383 runs a lil hotter, but never breaks 200.

Is there something we're missing or did I just get lucky? Sounds like Dave has the right stuff, yet he can't keep a 327 cool. Unlucky? or what's missing?

 

My .02 is full vacuum advance. Lean mixture at idle and cruise, 2 places where over heating is going to occur. Keep the cylinder temp down with full vacuum advance. I drove last year ion a 112 deg day with no problem.

 

Everyones combo is differant, we think radiator is a radiator, waterpumps , heads , head gaskets, the basic stuff with engine block also a topic. I will just add this to what I discovered few years ago. The water pump and closed impellors. We normally get one and its over counter from jobber. I have been adding a "disc " to the impellers on the store water pumps, I see Stewart Water pumps , makes their pumps , the old way,, with closed impellers. This keep water cavation down, pumps water not air. When GM service guys used to rebuild pumps in the shop, we never changed casting, just impeller and bearing assy.
You guys with fishing boats, some have the wing above the prop, keeps water above the prop. Same thing.
Last two cars that used this type of pump always ran about 90-100 deg above ambient temp . You can buy the $75 pump or install the $6 disc ,available from Summit or Jegs, Called the flowcooler disc.

Radiators, well I hear the new double 1.5 tubes are doing good.

 

If Jim runs at 175 and Dave runs at 195, then we need to ask where the sender is located. If Jim's is in the intake and Dave's is the cyl head, they might not be as far apart as we think.

We also need to consider the make and quality of the gauge.

We also need to differentiate beween "running hot" and "overheating"

I run the sender to my admittedly cheap gauge in the rear of the pass side cyl head, just for convenience's sake. I have a stock replacement 2 row brass/copper rad, and a 180 T-stat. My gauge reads 195-200 no matter what - idling, cruising, hot day, cool day. I'm not the least bit concerned - it doesn't "overheat", and I assume that the gauge would read lower if I moved the sender to the intake manif. I really don't care though - the gauge stays steady and the car never boils over. That tells me I have enough cooling capacity for my motor.

Stock radiator
Edel Aluminum pump
Stock shroud
Thermo clutch
6 blade fan
180 thermostat

 

It's all being touched on Jim, there isn't a single answer though. Engines produce heat; compression, running rich or lean, hot or cold plugs and timing can all add to the amount of heat created. Then add to that heat from a clutch or torque converter too. Based on that, different combos create more or less heat. We can't forget the oustide air and humidity as another influence.

I believe the key to controling the amount of heat produced is having a properly balanced cooling system. It doesn't matter if it's a copper-brass, mechanical fan and pump system or an alum core, electric faan and pump system. If the parts are matched and installed properly you won't have a problem.

Having too large of a rad core and not enough fan to move air through the core is an example of what I'm saying about balance. Many electric fans don't have shrouds and may move plenty of air. The problem is it only moves through part of the core which only cools the fluid that crosses it's path.

Looking at some stock factory '60s vintage cooling designs we know big blocks got heavy duty cooling systems compared to small blocks and AC cars got heavier duty systems than non AC cars. Differences included clutch fans and core sizes for the most part. The factory did a good job, it wasn't until the cooling systems didn't recieve maintaince that they started to fail. Plugged cores, missing or broken shrouds and fan clutches that no one knew to replace, even tired coolant mixtures... I bring all this up because, be it tired old parts or everything new - the system fails because each part does not produce the results the others in the system expect and need for them to function properly.

When I read someone has replaced the radiator, has a new fan and pump, the hoses are new etc. and still has a over heating problem I think they need to examine 2 things, the engine itself and it's tune (rich/lean, timing etc) and then the components that make up the cooling system.

In your own example Jim, taking the shroud out of the picture probably made more difference than putting the 2 core back in. Put the shroud on the 2 core and I bet you'll drop 10 degs. That 2 core can do the job with the heat your stroker makes, your nice alum core is good for more compression and more HP (heat) it might not like a stock water pump as well as it likes a high flow pump though... That's where the balance comes in.

Edit: You want to leave this here? or I can move it to heating and cooling...

 

Old radiators can also suffer from deterioration of the solder that holds the cooling fins to the tubes. If the fins no longer have good contact with tubes the radiator becomes inefficient.

 

Something else that effects the cooling system is rear end gearing. I have worked on guys cars and they kept the stock cooling system in place because it worked in the beginning but changed to 4.11 or 4.56 gears, headers, cam, trans cooler, high stall converter and just could not figure out why on a 90 deg day at 65 mph and 3500 to 3800 rpm the car was running at 200 to 210 and it never did before.

In these cases I think they started to over work the cooling system and an upgrade was in order. After changing to an aluminum radiator and shrouded electric fans or fan problem was solved.

Now add a modified big block, high gears, electric fan, no shroud, trans coolers, uncoated headers and a/c condenser and you really need a good, complete cooling system.

Also something I have noticed a couple of times is people are using the large water pump pulley. I don't recall the diameter but it is usually about 1" larger than the standard GM water pump pulley.

 

I'm really glad about this post. I have made several posts about my 327 running consistantly at 215-225 and have done everything you can imagine except replace the 8 year old three core radiator. I've ordered a 4 core from Ricks and should have it this week. I'll let you guys know how it works out.

 

Cast iron block 396 bored .30 over and cast heads. Rebuilt Harrison four row manual radiator w/shroud and six blade fan but no fan clutch. Alum intake and water pump, coated headers, 373 gears.

Mine runs under 180 even at idle in 95 plus weather.

 

Al, I use an autometer electric gauge. Sender is in the same place yours is, back of the pass side head.

Tony, yours is a good example of what works, even with the 3.73"s, your system can "Take the heat"

Dennis, you bring up a good point. How hot is too hot?

Us gearheads got in on our "gearheads" that cooler is better, and 180 is right. Truthfully, if you're not boiling over or puking out the overflow, you're not too hot. 220 is pretty normal for new cars. I've seen 255 in my vette, and it didn't boil or overflow. It did run like crap tho.


Airflow thru the core is real important. The blockoff plate I have in front of my radiator support absolutely prevents air from going over the radiator. I think this helps. My shroud is big and deep, and covers the entire core with a pretty tight seal to all 4 sides.

When I first got the vette a few weeks ago, she was heating up something fierce. Big problems in stop and go traffic, better but not great when moving.

Airflow seemed the obvious problem, and since the fans were working, I pulled the radiator. Found the outside of the core completely plugged with road debris. Cleaned it out and it's good as new, running at 200 with a 195 thermostat, all the time.

 

I have covered this before...
Those that run hot, are they used radiators? and if so have the headers been removed and cores manually cleaned?
As mentioned above, electric fans, do they cover enough cooling area?
Shrouds make a huge difference to the efficency of the fan, stopping air spillling off the ends of the blades.

As to Al /brass, sure the AL is more efficent, but once down to practical operation, if the dans, shrouds, tuning are correct, stuff all diff...if both are effective, it then falls back to the thermostat control.

I have run sb engines lean, rich, advanced, retarted, diff octains, unless one is way way out, a good stock radiator/fan and cooling system will run damn near everything I have thrown at it....even with 160* thermostats...
Well tuned run below the 180, off tuned thu not extreme get upto the 195*

Any issues I have run into is when playing with fans/shrouds, and location of trans coolers restricting flow to the radiator

Full on track engines are a different kettle of fish to a good street/strip or daily driver.

 

I installed a '66 Buick Skylark's 4-core A/C rad in my car when I installed my hopped up .060" overbore, 11.5 to 1 CR., 409" "W" motor in my car years ago!!

And it was fine.

Generally if you up the size and power output of your car's engine, then you need to find a rad that was used in an application that you are at now power-wise b/c that's what I did and it worked OK!!

And way back then, I ran 160 T-Stat's too!!

My car now has a cheap Summit/Northern Aluminum Radiator wide 1st Gen. aluminum rad in it so I figure it will cool my 496 fine..

pdq67

 

I'm glad this thread was started. One of mu first concerns after getting my 69' was the water temp reading. I have 350, .030 over, 3 core rad...and it will normally run 175-180. But at highway speeds and small bursts up to say, 80-85mph, it will quickly go to 195. It seemed to stabilize at this temp at higher speed, but the car being new to me, I let off back to 65 or so, and it cools right back down. I haven't done it yet, but plan to flush the radiator despite the color looking great. Many people fail to do this, or worse yet, they put more coolant in than they should.

 

And fwiw, my 350SS's engine STOCK had a narrow in width, 2 row copper rad on it!! Little-bitty light jobber, but it worked fine!

That's why I found the Buick 4 core jobber that was the same width, but was a saddle mount so I had to "hang" it in my car!

I've still got the Buick rad out in the garage! Had to turn mine in for a core back then so lost it.....

pdq67

 

I have a friend with a 67 Nova with a 406. He had the same issue with heat. He was running an after market pulley on the crank and found out that it was under driving his water pump approximately 40%. He changed back to a stock lower pulley and his problem went away.

 

Something I have found, that surely must contribute but I can't prove it is old freeze plugs inside the block. I've pulled as many as 10 out of old blocks and that's more than 1 set, means multiple overhauls and the plugs got knocked in instead of pulled.

I do not let machine shops put freeze plugs in my blocks, unless it is my buddy down in Texas. I do em myself, so I can shake the block and blow air thru the jacket and listen.

 

Good topic.

I've struggled with this on my wife's '68 SS-396, it's a stock 350hp rebuild with exhaust manifolds etc. It doesn't overheat, at least not yet and we avoid parade like traffic in August, but the gauge will read at a minimum of 190 deg when it's cool out and around 200+ when it's really hot out and the cars moving. I know it's not just the gauge, because you don't dare touch anything under the hood until it's had time to cool down or you'd literally burn your hand on the braces that run from the fender to the core support. I've had a 454 in a '69 Camaro, 11:1 compression and so on, with a cheap flex fan and no shroud and the car never got near 190 deg. even with the endless summer cruising up and down the Boulevard with the ocassional drag race.
I'm beginning to think that some castings are just better than others. Maybe there's casting flash, or sand? or just restricted passages that others don't have. These are rough castings and who knows what the inside of the water jackets in the block and heads really look like. Maybe it's not possible, I'm no expert on the subject, but it's all I can come up with.