Technical Cooling issues, need to pick some brains

That's something completely diffrent, you bring a layer (called boundary layer) of cold air in with your finger every time you move it into the flame, and no matter how fast or slow you move, it still takes time to warm up things (such as fingers) once most of the cold air has been replaced by the hot flame. See how slow you can move your finger through ONE flame, then redo the test with 20 candles close side by side and see if you can go through the whole line at the same pace or if you need to speed up.

 

Heat transfers only until there's no difference in temperature , then it stops. Heat only moves from hot to cold, in other words heat always leaves and cold never enters.

The rate of heat transfer is greatest when the temperature difference is greatest.


That means if you send hot coolant zipping thru the radiator so fast than it cant drop the coolants temperature, and then send HOT coolant back into the very HOT engine, the engine's heat energy CAN NOT be dissipated into the coolant fast enough. Moving the coolant faster thru the engine will prolong the moment that it boils because coolant is not there long enough to collect heat. This delay of boiling coolant should not be mistaken for cooling an engine.
At this point, the iron is beyond operating temps and the iron moves. the coolant is completely heat soaked and looses its liquid state and boils.

Funny how steam powered electricity generating plants strive to transfer heated water as quickly as possible to minimize heat loss.

 

Agreed.

Well... Imagine this:
Coolant temperature running at a steady 220 degrees coming out of the engine, and 180 re-entering from the radiator.
You increase the flow seriously. The water spends less time taking up heat inside the engine, as well as it spends less time loosing heat in the radiator. New temperaturs is 205 leaving engine and 195 reentering. Still averaging 200.
Sure, a thermostat would probably change that a bit since it controls when there's any cooling at all, but the point is you don't need to leave the coolant out of the engine until its freezing cold, just cooler than the engine. The higher the flow, the less temperature diffrences there is, twice the flow at half the temperature diffrence still removes the same amount of heat energy.

 

Cap good?

 

"twice the flow at half the temperature diffrence stillremoves the same amount of heatenergy."

Not if all things are equal in a temp change over time equation.


First, the rate of heat transfer into the coolant, or how fast the water will pick up heat isn't going to change off of its plotted bell curve, its just not. It's a temp difference over time equation. Remember that Its a bell curve. The same goes for the shedding of heat.

The only way to flow 2 times (twice) the flow thru an engine block is to move the water thru in less time. Naturally and obviously the only way to do this in a closed system is to draw it thru the heat exchanging radiator at the same 2 times rate. So since we are bound to temp over time equations, the only way you'll drop equal heat energy is to have a radiator that's 2x as efficient or 2x as large.

Moving coolant faster thru the engine keeps the coolant cooler. Faster means it picks up less heat. Your temp gauge tells you the temperature of the coolant only, not how much heat it's transferring. Now of its picking up less heat how is it acting as the medium to keeping the engine cool? Moving coolant thru the equal efficient radiator faster keeps the coolant warmer. That means its shedding less heat. The goal of a coolant system isn't to establish an equilibrium and prolong over heating the medium from reaching a boiling point. Rather its goal is to gather heat, move heat, and shed heat. 3 parts right.

The pressure raises the the boiling point. By raising the boiling point the coolant or medium is capable of holding more heat and moving more heat. Once the coolant boils and vaporizes there is no heat transfer. Anti freeze alters 2 things. First it does mildly raise the boiling point of the mixture. Second it greatly alters the ability to shed heat, it hangs onto heat, keeps heat from leaving. A 50/50 mix decrease the ability to shed heat by 30%. That's exactly the same as having 30 smaller radiator with straight water.

Moving coolant faster will let you run longer before raising the temp to boiling. Maybe that's enough time to get 5 or 50 laps to the finish line. Maybe it's a long enough time to get to grandmas house and that's all we really is need enough time. But it's not going to allow better transfer of heat out of the engine, just an increase in the mins needed to boiling the coolant by not letting the coolant pick up heat.

 

G-son has it correct. OP needs a larger radiator.

 

You mentioned that you thought a 195 thermostat was high, but back in the 70's we routinely changed them to 195's up here to get more heat out of them for winter driving and defrost. We never took them out when it got hot in the summer. That thermostat is just there to bring it up to operating temp and then open. It does not change the max. temp range of the engine which is controlled by the amount the rad cools it. A pressurized system won't boil until you are well over 212 F. A larger rad won't hurt, but I still think the crud in the engine is a bigger issue in the long term.

 

hard to

HolySmokes! You sure about that reading? Best double check as those pipes will be glowing red at night. If idle temp are above 450ish I get to doing something. Sometimes it is hard to read pipes because they are chrome or shiny but 585 is dangerous, fatten the idle ckt, if the motor doesn't immediatly sound and run better then the readings are wrong.
20 degree differential across the radiator is very good.
I'd be getting a much colder plug too, you said yours is midrange, I try to go with a -8 heatrange with projected tip and if they foul after a while I'll back up to a -7. The coldest possible heat range plug will make a significant difference in the coolant temps.
Fatten the idle ckt, thats for sure. The idle ckt is always functioning, if it is that lean at idle then the cruise will be lean as well. The engine sees the total fuel thru the boosters and the fuel thru the idle ckt.

 

how about throw some jet at it ??
also make sure the timing is indeed 36 @ 3000 , mechanical, , and use a vacuum advance HOOKED TO MANIFOLD VACUUM.
I have a 7 row radiator in my car (!) yes 7. It is a section from a locomotive radiator. So the too thick radiator thing.. I'm not buying it.
An easy down and dirty trick, is to open idle adjuster screws a lot, like 4-5 turns, and drive it..
it will idle bad, but will bring in enough extra fuel to see if it makes it happier. (temp wise) on highway.
If it's better, throw some jet at it.. + 4 can make a huge difference, if you're on the edge. also, the vacuum advance will bring temps way down, if it's tuned right.

 

Cast iron or steel doesn't start to glow until about 900 degrees f but 585 degrees is very high at idle.

Are the head gaskets installed correctly? Somebody didn't get the bright idea to port match the gaskets to the heads so they made big holes and all of the coolant is flowing into the block through the front of the head and into the intake manifold out to the radiator leaving little or no flow through the back of the block and heads. I've seen 2 cases of this. One was done intentionally and the other was steel head gaskets being used with water and the gasket rusted away. You will notice the rear of the head is hotter than the front.

 

I am****uming the fins are spaced further apart on that radiator, than on a common car radiator. When radiator thickness goes up fin spacing is usually altered to make it easier for the air to get through. It's all a bunch of compromizes.

 

after some searching on mopar boards, found the idle temps to be in the middle of what others are seeing. 450 to 650 degrees. So I cant make a move just based on that. But With the old screw style water pump at freeway speeds before I was pulling 185 degrees, at idle that thing would shoot way up.

The one thing that has stuck in my mind is this balanced thermostat may be screwing up. But I honestly think there is too much flow to do what needs to be done. So going to toss a 195 thermostat in there, and roll the dice and pray it cycles better. Will keep you posted.

And 7 row off a LOCOMOTIVE is AMAZING!

Jet sizes I jetted this car using plug readings, any more jet I am way too fat... Got good tan right now...
Idle is a bit fat right now, you can smell it for sure, but not so fat your having to wear a gas mask.

 

If the temps are accurate and it smells 'fat' idling outside then a possible explanation is the cam timing or engine timing is off and that you are firing right on top of the piston raising the egt's and creating excessive heat in the coolant.

 

After many freeway blasts for 5 to 10 miles changing speed... sitting in traffic, logging temp outside etc when doing it. Here is the results.. anything over 80 degrees outside results in 10 to 20 degrees more of engine temp at freeway speeds, anything under 60 mph the car will hover around 185 to 195.

I honestly thing the motor gets on freeway and is generating more heat than it can shed.. idle and around town its fine so I am currently doing what someone mentioned on page 1.. Radiator... Bought a Walker Rad... damn I hope this thing is as good as everyone says it is... Z series.. now trying to get this cooling fan to fit... Will post more when I get it done and tested.

 

Well it was cooling before correct? if not then here is a question that no one has asked and begs to be asked. What year Dodge block do you have bored +.030? The '75 and later blocks will take a .030 bore easy enough but they are a lighter casting and don't cool as well as the early blocks or so I have been told.

Next you were running it hard, they all get hot when you work 'em hard. Sometimes it take a while to cool off once you get one hot(er) then usual.

Next you never mentioned compression ratio. The reason I mention it is that it is harder to cool a higher compression motor then a lower compression motor. I call it the blivet principle. If you stuff 10 pounds of***** on a five pound bag and set it on fire it will burn hotter then if you stuff 3 pounds of***** in a 5 pound bag and set it on fire. The tighter you pack that***** the hotter it burns.

Just some things to think about aside from the normal stuff that is going to get mentioned.

 

I love The PNB explanations.. haha..
9 to 1 maybe 9.5 to 1 on a good day...
Over the times I did this I kept major restraint on the right foot.. eased up to speed.. no radical changes in rpm or load. Light and easy to get a good control for the study. 1975 block and bored .030 I was going through a list of all the things its done since day one.. so we will see if my calculations are correct.. If this fixes the damn thing and I can run 80 on the freeway I'm going out of town..60 mph on our road ways down here will get you ran over.

 

hey genius, did you try more jet yet ? total timing + vacuum advance = ?
you guys kill me, you ask for advice, then***** on it. .

 

I covered this early on there Einstein
35 degrees total timing... all in by 3200 rpm. NO VAC
Have tried more jet... falls on her face and blackens plugs with any more jet than is in here. No power valves. Have 64s in both carbs, running direct linkage now with no progressive.

 

This why they call 'em "Hot" Rods. There are a few basics that you probably know already but will repeat for "make sure" points:
1. Best fan is a 16 to 17 inch steel "ford style" fan you see in Speedway. I found them to really do the job period.
2. Fan spacing..5/8 to 1 inch from radiator.
3 Fan shroud a must. Doesn't have to be gauwky, just so the fan is mid point in the shroud i.e. half the fan in and half out.
4. Better advanced than retarted in the timing. Put in as much advance as you can without affecting the start or too much of the top end speed.
5. Check the temp sender and gauge. I know. It's a pain in the*****. But I have a 52 truck with a 350. It reads 260 degrees. I put the laser temp on the goose neck, 195 degrees. The sender or gauge is broken but I'm to lazy to fix.
6. Check the sender location. Try to locate as far from the exhaust and as close to the goose neck as possible.
7. Sometimes you can get a smaller fan pulley to move the water better. But as you know, too much and it'll work opposite of your objective.
8. Now this is tricky, but if your running a 185 thermo, sometimes it's better to run a 195 or 205 thermo to keep the water in the radiator longer. In some cars it's better to go to a 165 thermo. Only testing can****ure you of the results.
9. If it's not boiling over or impossible to start after you shut down. Regardless of temp, do loose your cool. You'll be fine.

 

If you are going to replace the rad, I would suggest installing a triple flow. Typically in down flow rads, the coolant chooses the easiest flow path thus only using about 1/3 of the cooling surface. I have several cars with the 215 aluminum Buick/Olds engines. They are notorious for over heating. In 1987 when I bought my 62, the engine over heated all the time. Even after I rebuilt the engine, put on a high volume water pump, used water wetter, and installed dual electric fans, it still puked. In the early 90s, I went to Cool Craft and bought a 4 core brass rad with triple flow. Have never had a problem since. https://www.coolcraft.com/radiator-core-styles#TF Since then, I was talking to a local rad builder for serious truck rads and he told me that he builds in triple flow to increase the ability to dissipate heat.

Warren

 

ha-ha! I'm trying to come up with another smart guy name to be funny, can't remember one.. duh..
I was hoping you would drive it long enough with it "way too rich" to see if it cooled down, forget about the plugs and the hesitation for now. just see if the cooling issue is better.
then you can work on the plugs ,and tune up..sorry to sound like a smart****, trying to be funny : )
really curious if it would fix the highway heat(it did on mine) 440 tunnel ram, 650 holleys X 2 . ran no power valve,and tried to tune for tan plug, no dice. put power valves back in there, jetted it up,and leaned out the idle circuit with bigger air bleeds. they like the plugs a little darker than a single 4 barrel set up..
the jetting doesn't effect the idle mixture at all, so that shouldn't change. dang it, I just don't want you to go through all the stuff I did, and then fix the carburetors.. I chased mine for about a year. Yeah, locomotive radiator, bigger fan, several thermostats, etc.. I'm talking about my roadster, 440 mopar 11:1 compression, tunnel ram, etc..
Also, having no power valve is like dropping 8-10 +/- jet sizes,as there is no enrichment from the power valves, so essentially you have what ever size jet - the power valve . (subtract)

 

You mentioned 3 row alum rad. The performance is 2 row 1 1/4 inch rows as mentioned hot with speed increase radiator

 

here is the latest...

Walker z series installed.. 1.5" taller and staying 185 on the dot... ran it on the freeway even in the cooler temps I would see it work up to 190s not anymore. 185 to 187 is my top temperature now. With coolant and water mix only. no additives at all. Will know when it warms up next year but now I have a car I can drive on the freeway with ease finally...

Figured I would give yall an update. who would have thought a big ole walker would save the day.

Thanks everyone for the input...

 

AWESOME !!It's nice to not have to worry about that all the time! thanks for the update !

 

Glad to hear. I've been following your cooling troubleshooting conversation. I didn't have much to add that had not been covered but enjoyed the conversation/education on the topic.

Mike

 

Running the U.S. Radiator copper/brass, 4 row, triple pass with a mechanical fan in my '52 Chevy with A/C works great for me. On 100 degree days with the A/C on, it runs at 180 degrees in traffic. On cool days without the A/C, it runs at 140 degrees. The motor is a basically stock sbc 305.

 

I would posit that your engine is running far too cool for proper efficiency. Me? I like to use 195º thermostats, but I also believe that the factory engineers know what they are doing, too.

Your car, do what you like.

Cosmo

 

Have you tried changing pulley sizes? It could be moving too much water not giving it time to cool in The radiator, could also be moving too little water.

 

My 383 Mopar had air trapped in the block, did the same thing. I then worked at getting all the air out and everything went to normal. I can watch the thermostat open and close by the temp which is always 185 - 195