Tony Cutlass

I have a 1970 Cutlass S. Lenmar Motor Sports short blocked it for me and bore it .30 over. My problem is that the engine is running up over 210 degrees. I asked some time ago on this site about thermostats. I was advised to run a 160 degree. I don’t think that is right. It seams that the thermostat never closes. The temp here in Dallas is around 100 degrees now. None-the-less the car should be able to run at that outside temperature. I'm guessing that with the additional HP output for the engine that the original radiator may be too small. I have also been advised to install an electrical fan, but I would like to stay as close to original as possible. I'd bet that I'm not the first person that has seen this. It’s frustrating to have this car in the garage and not able to drive it more than 10 miles.
Any help is greatly appreciated.

71 Cutlass

Tony,
I live down the road from you. Have you checked the usual suspects...fan clutch, do you have a four row/core radiator..is it any good? Is radiator cap still good? What temp spark plug are you using?
I use a 160* thermostat in my 350 w/ 10.5:1 compression (W/big block valves), a four core radiator and heavy duty thermal fan clutch and drive 30 miles down Central Expressway @ 70mph with A/C (and 3.42 gears..so high rpms), and no problems. Check basics first. If all checks out, you could "try" a 180* thermo and see if it works differently.

Aron Nance

Tony: I was having a similar problem with the Silver Bullet two years ago. Run about 190 in moving traffic on LBJ. Hit traffic tie-ups, and the gauge went up pretty quick to 210-215 (summertime, 100 degree days). Replaced w/a new 180 degree thermostat (pellet type, sorta hard to find), put an electric fan (manual switched) in front of the engine fan (close tolerance, about 1/4"), but seldom used, now. Best thing done was to go to an aftermarket 2 core aluminum radiator, w/very large tubing. Problem solved. Am sure others will jump in/w/their stories. Good luck! Our North Texas Olds Club tomorrow (Sunday) is in Arlington at J. Gilligan's at 2 PM. If you decide to come, DO NOT GO OUT IH 30. 1st place Rangers are playing Boston in the Ballpark at 3:05! Aron

Petmil

thermostat shouldn't make any difference to cooling just lets the water flows. Your other cooments are probably closer rad size fan size etc. This is a common problem with a lot of rebuilt cars. I would check all of the above!!!! Peter

Tony Cutlass

Thanks for the quick replies, "71 Cutlass" and "Aron Nance"

I think the radiator is original, but it has been cleaned. Would it be a 2 core or 4 core? If I need to find a lg tube 4 core where should I check in the DFW area. Right now I have the radiator out of the car. The cap is a new 13 lb. I’m not sure of the spark plug temperature.

Thanks for the I-30 traffic tip Aron. Maybe I'll come to the club meeting and we can visit further on this. I also want to come to the Zone Show again this year.

joe_padavano

Aron's two row is an aluminum radiator, which uses much wider tubes that the factory copper radiator. The two row aluminum is as wide as a three or four row copper unit.

BlackGold

And if anyone's wondering why wider tubes or more tubes cools better, it's because there's more volume of coolant inside those tubes at any given time, which means the coolant travels through the radiator more slowly, allowing it to transfer more heat to the outside air.

Some radiator cores also use more fins, which obviously provides more surface area to transfer heat to the air.

Tony, your radiator may have been cleaned out, but I'm convinced that will never be as good as replacing it with a good quality new core (whether copper/brass or aluminum). I'm not convinced the cleaning does all that much, and I think that part of the problem with old radiators lies in increased thermal resistance between tubes and fins, which has nothing to do with cleaning.

72 w29 all green

I see you mentioned having your shortblock done. I had a similar problem with my 455 running a little hotter after the engine was rebuilt. The builder told me afterwards he preferred having pistons on the tighter side of the tolerance . Live and learn: ask all Q's BEFORE the rebuild and if you don't like what they say, move on to someone else.

Lady72nRob71

Tony - welcome! I am somewhere around you also. What general area are you located?

Do check your fan clutch. When it is running hot, it better be blowing a LOT of hot air at idle, accompanied by a roaring sound. If not it may be bad.

Make sure the flexible rubber seal is between the bumper and rad. support.
A three row factory replacement radiator or 4 row should be used - never the 2 row factory type.
The two row aftermarket aluminum jobs have wider tubes, so they will work more like a 3 or 4 row factory type. These are good if you do not mind loosing some stock appearance.

Make sure timing is correct and not running lean - sounds like you should have it in good tune.
Where is your distributor vacuum advance line hooked to?

If 210 is the highest it gets, then I would not worry too much, as the car (and cooling system) was designed for use with a 195* t-stat, allowing an easy 200-205* operating temp.
The temp light comes on at 250*.

My 350 does about the same as yours. At 100*+, it runs about 205-210. As soon as the outside temps drop to 90 or so, it will run at 185. (I have a 180* t-stat)
The bad thing is that I (as in ME, myself) overheat at that temp, so i do not drive the vert when it is above body temp outside...

Tony Cutlass

Good stuff Rob,
Thanks for the tips and info. Im in the "Learn as I go" process on this. First discovory was that I do not have a fan clutch and the fan is a 6 blade flex fan. So these items need first attention. I am waiting for a new Aum. wide 2-row radiator to arrive next week. I have also been advised to find a High performance water pump. So that is where Im at today. I'll recheck the vacuum advance line.

The carb (just rebuilt) has a hesitation on acceleration. I have been told that is common for the Quadrajet. Any advise or direction on this acceleration issue?

Tony Cutlass

BTW - I'm in Duncanville, TX, just south of Dallas

sworthy555

Tony, My SX has a 180 t-stat with a four core radiator and runs about 190 degree's in the San Antonio heat wave right now.

As for the hestitation I had the same problem and had the carb rebuilt twice and still had the hesitation. I was getting very frustated so I replaced the power piston, primary metering rods, accelerator pump and used a different base plate off another 7040251. Originally when I started it up the high idle would never hold and after I changed the base plate and the above parts it ran great. I basically used the process of elimination since I had a couple of extra carb's around plus did a lot of reading on line about the quadrajet. Must of taken the carb off the car a dozen times but finally got it right. Hope this helps!

jaunty75

This is incorrect. The heat transfer rate is proportional to surface area and fluid flow rate. More heat transfer area, yes, that will help. But slower-moving fluid? No. It's counterintuitive but true. A faster-moving fluid increases the heat transfer coefficient.

Volume has nothing to do with it, either. A larger heat exchanger, which is what volume would be related to, would increase the AMOUNT of coolant that can be cooled, assuming the heat transfer area increased in proportion to the volume, but it wouldn't increase the RATE of heat transfer nor cool the coolant to a lower temperature.

lweinmunson

Tony, My '70 S runs about 170 while moving in Dallas traffic. I don't see where you mentioned if your heat was moving or in traffic. Sitting at a nice long light in the 100+ weather it will slowly move up to the 200-210 range. Besides checking to see if your fan is moving enough air at idle, does it have a fan shroud? Adding one to my car majorly helped keep it cool once the summer got here. If the temps keep on climbing while the car is moving more than ~40 or so then it's probably not going to be the fan or the shroud.

Lady72nRob71

Hey - another Texan! --Howdy!!

BlackGold

You misunderstood me. Or Physics.

First, the volume of the tubes is relevant, because that is what makes the coolant flow slower, ie spend more time, in the core of the radiator. The water pump is pushing a fixed volume per second of coolant, regardless of which core you have. If that volume of coolant were to hit a very narrow restriction, the velocity of the coolant would speed up tremendously and spend very little time in that restriction. If that volume of coolant were to encounter a radiator core whose tubes held 100 gallons, then the coolant would slow to a snail's pace and spend an enourmous amount of time in the radiator.

Second, slowing down the coolant -- in the radiator -- does indeed cool it more! Note, I am not saying that slowing down the coolant inside the engine block and heads will make the engine run cooler. Just the opposite. The ideal cooling system would have the coolant going through the engine like a fire hose, but spending hours inside the radiator. The result would be an engine bathed in coolant the same temperature as the ambient air. (Of course, this would actually over-cool the engine, which is not ideal either.)

dc2x4drvr

Tony, yah, get rid of the flex fan, and get a AC Delco fan clutch..
BTW, I was running around 190 in stop and go traffic from Richardson to the strip in Crandall, my cooling system is stock Olds, with a 160 stat.

72 w29 all green

Who told you q-jet hesitation was common, the carb rebuilder? Was the problem there before it was rebuilt? Anyway, describe the hesitation. Does it occur just off-idle or when you "nail" it?

88 coupe

I read what he read. He misunderstood nothing.

If indeed, there was a "misunderstanding" it began with you, and the composition of your post.

Your thesis assumes that, under the same conditions, a given volume of fluid will be cooled quicker than a smaller volume of the same fluid. It also assumes that fluid moving at a slower rate will give up more heat than fluid traveling at a faster rate (moving more volume) in a given time frame.

Neither assumption is based in fact.

In this case, more air moving through a less restrictive heat exchanger, is what makes the system more efficient.

Norm

71 Cutlass

OH no..."Will it go round in circles"...come on, clap your hands ya'll.

BlackGold

Maybe we're all misunderstanding each other.

Let's forget about the speed of the coolant. I'm simply trying to say that the longer (time) the coolant spends in the radiator, the cooler it will get. And the cooler it is when it returns to the engine, the more capacity it has to draw heat from the engine.

The ultimate radiator is the one you find on boat engines. The "coolant" is pumped into the lake, where it sits until the following Saturday before your engine sucks it up again, nice and cold.

If you insist that moving the coolant through the radiator as quickly as possible is good for removing heat, then I'm at a loss to explain why Olds (and every other make) use higher-capacity radiators for heavy-duty applications. They don't just add more fin surface area, they add more tubes (which hold more coolant, which slows down each individual molecule of coolant, which means each molecule spends more time in the radiator).

And yes, I do understand that heat transfer from a fluid is improved by adding a little turbulence (which typically comes along with velocity). But that's not what we're talking about here.

71 Cutlass

Get ready Brian, he will list a zillion of your logical, perfectly worded quotes and tell you how they are illogical and nonesensical. That's why you see the "Oh no" post above, b/c I know what's coming from old "88"

BlackGold

That's OK. There's a lot we can learn from Norm. There's a game I like to play with one of my engineering buddies; we call it Parlour Physics. We ponder some real-world mystery and try to solve it using our admittedly limited knowledge. Beer is usually an essential diagnostic tool. There is no winner; you don't even have to agree. It's the process that makes the game fun. I bet Norm would fit right into the group.

Lady72nRob71

Amen.

<burp>..........

71 Cutlass

If he's always allowed to be seen as the only one who ACTUALLY made a cogent point then ahh, I'll agree to that.

88 coupe

Yes. Easier to call it a "misunderstanding" than to clarify and/or defend your original post.

Or you can change the subject altogether:
Yes. Lets just eliminate the water pump so the system will be more efficient.

From your original statement:
It is what jaunty75 (rightly) took issue with, and what you have yet to address.

There is nothing to "misunderstand" because it is based on a myth.

I "insist" nothing of the kind.

Looks like all you (and your new friend) can produce are "Red Herrings", "Straw men", and "Ad Hominem" attacks, none of which are used by mature adults.

I am finished with your childish BS.

Norm

71 Cutlass

Tried to warn you Brian...now for my next amazing act of fortune telling I will......

BlackGold

The myth of which you speak is when people mistakenly say that you should slow down the water pump or use a restrictor so that the coolant will spend more time in the radiator, thus cooling the engine better. So I'm agreeing with you: that is a myth -- because they only got it half right. The problem is, their restrictor also slows the coolant inside the engine.

I'll say it again: The ideal cooling system would have the coolant going through the engine like a fire hose, but spending hours inside the radiator. If someone would like to post some thermodynamics equations which refute this, I'm open to learning from you.

"Childish BS"? I don't know why you're getting so worked up, Norm.

88 coupe

Looks like I need to clarify my position.

Your use of "worked up" assumes that I wrote some sort of emotion into my post. It, like your previous false "assumptions", only serves to divert attention from your inability to address your own statement.

Here it is, again:
You can clarify it, defend it, or continue your childish diversions.

Norm

71 Cutlass

"Will it go round in Circles"...http://www.youtube.com/watch?v=6NYIf...eature=related.

Brian this Eric Clapton & Billy Preston video(link above) is what I attach to Norm's "Circular" posts b/c all he does in argue in circles with no definitive truth to disprove anyone who disputes him. Remember to clap your hands while watching the video

captjim

Thermodynamics aside, can we agree that if everything is up to snuff, the car should not overheat?

Is this a 350 or 455? Is it overheating at idle or cruising? It has been my experience that nearly all cruising issues are radiator related. I replaced the one in our 71 Skylark (355 Olds in it) with a plastic tanked aluminum rad from a P-20 GMC van. Inexpensive, cools great here in Fl. Very minor mods to install, but I do run an external trans cooler. Overheating at idle is usually airflow, fan or shroud.

Also, (this one kicked my a$$) I have seen where some replacement stats can be restrictive. Spend the $10 or so on a Robertshaw or Moroso high flow stat. My car actually ran better with a 180 than it did with a 160.

71 Cutlass

Captjim,
I switched to a 160* thermostat from the 180* hoping to cool the engine better (by releasing water into the motor before it got too hot). Your post said that the 180 worked better. Anything you can put your finger on that leads you to understand why? If it's something substantial I might go back to a 180. Also, are the high flow thermos really that much better?...I've never tried one.

jaunty75

Just be sure you don't cool it too much. Running too cool is about just as bad as running too hot. The real question you should be answering is what temperature does your engine run at? 190-195 degrees is where it should be. If it's in that range with your 160 thermostat, fine. If it's less than that, put the 180 back in.

By the way, the thermostat does not "release water into the motor." It opens and allows coolant FROM the motor to enter the radiator. The point of the thermostat is to stay CLOSED, thereby isolating the engine from the radiator, until the engine reaches the temperature at which the thermostat is designed to open. This allows coolant to begin to flow into the radiator and keeps the engine at the correct operating temperature.

If you have a thermostat that opens at too cool a temperature than it should or that is stuck open, the engine coolant is open to the radiator and coolant flows through right from the moment you first start the car. The engine thus never has a chance to warm up before coolant begins to flow through the radiator, and thus it takes a longer time for the engine to reach operating temperature, if it ever does. This is not good for the engine.

BlackGold

A simple analogy seems appropriate (though I'm sure you will claim it a strawman or red herring):

Two men with body temperature of 98.6 degrees, wearing summer clothes, walk out into a blustery winter day of zero degrees. One stays outside for 5 minutes, the other 5 hours, before returning to the indoors.

Now tell me: which man's body has transferred more heat to the outside air? Which man's core temperature will be lower? (And this despite the fact he actually has a little engine inside him burning fat and producing even more heat than the guy who stepped back inside earlier.)

The longer a warm object is immersed in a cool fluid (air), the more heat it will transfer to it. What don't you understand about this?

71 Cutlass

Jaunty,
Sorry for the wording confusion, read "into the motor" as "allowing water to circulate through the motor" (Obviously from engine to the radiator). At any rate, my car has 10.5:1 compression, and as a result never seems "cold", esp. with 3.42 gears, 2500 stall, and A/C in stop/go traffic in the Texas weather. What do you know regarding the high flowing thermos?

Brian...you are the bravest person I know

Waiting to see if it "Will go round in circles" again.

jaunty75

But water (coolant) always circulates through the motor, from the moment the engine is started. The thermostat doesn't control this. The coolant just stays in the motor until its temperature reaches the level necessary to open the thermostat, and then the coolant from the engine starts to flow through the radiator. Until that happens, the coolant in the radiator is just sitting there doing nothing (or maybe it's circulating only within the radiator).



Well, this sounds hugely subjective and a bit frightening. How do you define "cold?" And what does the compression ratio have to do with it? Can't a 9.5 to 1 or 10 to 1 compression engine also run too hot or too cold if there is a problem?



Not a thing, and that's not the point. The point is, and as I asked earlier, what is your engine's operating temperature? Until you answer this question, you can't possibly know if it's running too hot or too cold, so you can't possibly know if your thermostat is the proper one. Changing it just because the engine "feels" too cold or too hot is the wrong approach. Measure the temperature of the engine coolant, and then select the correct thermostat.

Personally, if my engine is stock and the thermostat called for in the service manual is not keeping the engine running at the correct temperature, I would be looking for the cause of this, rather than trying to cover over the problem by installing a different thermostat. Poor cooling can be due to a number of reasons, the most likely of which is clogged or corroded coolant passages in the engine and/or radiator.

71 Cutlass

I understand about the thermostat, but water isn't released until motor reaches a certain temp..hopefully I have explained that. As for not knowing the motor temp, I actually do not know the answer(never used a gun on it), however with a small block motor that has been modified, the motor is not built to handle the extra heat brought on by flat top pistons, different gears, higher rpms, big block valves, etc. This used to cause a great deal of "spill over" from the radiator over flow line. To me, even w/ out taking the temperature of the motor, I can tell the motor had heating issues, all brought on by modifications the Olds engineers never intended for my vehicle.

jaunty75

Remember one thing. I know nothing about anything. I certainly don't know anything about what the effects are of modifications to an engine on its operating temperature and whether the engine should be allowed to run hotter or colder than what the factory meant. It seems to me that, regardless of the modifications made, the engine's operating temperature should not deviate too much from the stock engine's value. That's just common sense. Too cold and it runs inefficiently, and too hot and the engine can be damaged.

But, again, even if you aren't sure what a good operating temperature should be, you can't do a lot until you actually know what the temperature IS. That's your starting point.

I mean, look at it this way. You find a guy that knows something about this, and you tell him that you think your engine's running too hot. What's his first question going to be? "What IS the temperature?" Right? What's your answer going to be? "I don't know?" That's a hell of an answer.

71 Cutlass

I have an "educated guess" I suppose regarding the engine temp. As I said, radiator used to overflow, but I made some modifications (dropped to r43 plugs, purchased new radiator and fan clutch, dropped to 160* thermo stat). No more over flow, but yet still cannot touch dipstick w/out incurring 3rd degree burns...so motor seems to be within good operating temp due to the non overflow, yet hot engine components. Of course this is not exact science I admit. Anyway, I'm one who ,even though things are working well, am always looking for a way to make them work better, thus my question. Who knows, you may have promted me to get up and actually go have the "actual" engine temp taken. If I do end up taking the time to get a gun to do it, you will get the credit.

88 coupe

Doesn't matter unless it is not the original engine or cooling system.

Asked in his previous thread:
OP chose to ignore it.

When the thermostat is closed?

Your "analogy" does not include any references to the relationship between the volume, or speed of either the cooled or the cooling media.

Not only a "red herring" but another of your childish diversions.

Norm