Are you sure about those temps???

If the tstat housing is 210 the upper inlet should also be 210.
The lower outlet should be a lower temp.
Please redo the temps.

Also, how are the spark plug readings?
Post a closeup pic of a plug if you can.

What other mods have been done to the engine?
I see you have side exhaust, do you have headers too?

 

It is possible to get a difference from stat housing to upper hose...I noticed that taking readings with my Raytek...so I just stick to the hose for the readings for differential between upper/lower hoses...
One thing for sure,you cannot get an accurate reading off chrome housings...mine happens to be black...

 

I have found that with the IR guns that if I hold it real close to the hoses it heats up the front lens on the gun and that seems to make all readings after the first one read hot. I too was seeing higher temps on the rad outlet untill I realized that the lens was hot from reading close off of the top hose. If you let the gun cool a little between readings taken very close to a hose it seems more accurate. I believe the IR guns work fairly well but the only way I ever got "true" temp readings was by placing thermocouples into my rad hoses.

Greg.

 

Good point....I take mine from 12" for that very reason...think main thing is being consistant...ie...just shooting hoses....I have also taken readings off a CB rad surface to compare with upper/lower hose readings...have not tried that on my aluminum rad though...
Rich

 

You might get different readings from the housing to the upper inlet, but there should be no substantial difference.

The guns come in different qualitys.
I friend of mine just paid over 400 bucks for a really good one, but he uses it almost every day.

I use a lab type digital thermocouple thermometer that has an accuracy of 1°C. It was less than 20 bucks wholesale but not as easy to use as a gun.

 

I took some readings today after a 20 min drive around town with A/C on and 95F ambient temp, I shoot at the hoses not the metal :

thermostat housing : 210F
upper hose : 210F
lower hose : 208F

I believe these readings dont reflect a good cooling system, do they?

Is it possible that since this radiator has larger core than the original, the stock old water pump just cant circukate water good enough through it? my W/P is stock and original one, it produces a little squeeks while rotating, anyway its my only stock and original cooling component and I ordered a stage II water pump from stewart and waiting for it to come.

I still use the stock exhaust manifolds, and they become VERY hot, I measured them and found they reach 700F very easily.

 

I am surprised that no one picked upon the fact that youre running without a vacuum advance. Most engines need from 20*- 32* of idle timing. Idle timing is defined as initial timing + timing created from the vacuum advance can . You have only 14* from your initial timing and that is about 12* short of optimum.

I would ditch your non vacuum advance Mallory distributor and get a stock Delco . You need a B20 or B26 vacuum can and while the distributor is out you could blueprint it to the correct tolerances and recurve the ignition map to your engines spec. Use quality ignition parts (28-32 oz HD points( BW A112) and a quality cap and rotor(Accel 8120)

Adding a vacuum advance will provide 16* of idle timing and setting the initial timing to 8*-10* will get you into the mid twenties which is what most street engines like.The exhaust gas temp will lessen and your overheating should disappear.

 

That is better...but your differential should be much more than you are getting...you need to see about 20-25 degrees cooler at outlet(lower) hose...
It is possible your pump impeller has deteriorated and is not delivering enough volume...and that squeak is the pump bearing going out...I use stock pumps on both vettes......even on my 502 with a 4 row CB rad...never sees coolant temps over 200 F in 100 F weather...in traffic or otherwise...
I have a Dewitts in the 78 L-82 with A/C...I don't have A/C on the 69 502..
Rich

 

Thats interesting, everyone here calls for a 10-12* at idle and 36* total, and I thought I am pretty close to be perfect. Based on what you suggest, I must have more advanced initial timing? what about the total timing? keep it at 36* or rise it with the same amount? which will make the total 48*.

 

Have you experienced any pinging ???

 

no not at all, in the matter of fact, as soon as I rotate the distributor advancing the timing, the RPM went up and I had to reduce it from the idle screw to compensate.

 

I didn't realize from your other dist. timing post that you have no vac advance. More timing at idle will surely bring the temp down....

 

Did anyone ever wonder if drilling a hole in the stat was a real good idea, why nobody makes one that way? I mean how in the hell did all these cars get off the line without air trapped in everyone of them?

 

Good question, never tried it, yet have never had a problem....

 

I first heard of the hole drilling in the late 60's.
On some old vehicles with a straight up neck and a top tank radiator with a center cap, you could see the air bubbles come from the upper hose while you waited for the air pocket to disappear while filling.

Some cars such as BMW's have what looks like a brake bleeder screw on the highest point of the cooling system which happens to be the engine side of the tstat housing to bleed the air off.

A lot of replacement tstats, but not all, do have a tiny hole (1/16") and others have a dimple formed on the sealing edge to allow air to escape.

The factory filled the cooling systems with a machine that first created a vacuum that also tested for leaks and then filled the system with coolant in a matter of seconds. Very similar to evacuating and filling an a/c system, also without trapped air. Hence, no need for a hole or bleed.

 

Your temps pretty well say it all.

First of all, it doesn't matter if your engine is running at 160° or at 360°, you are not rejecting the heat thru the radiator. As a general rule of thumb, as the inlet temp gets higher, the difference between the inlet temp and the outlet temp will decrease. But you only have 2° at idle after a run. Also the faster you go the hotter it gets.

The causes for this are
-clogged radiator (internal deposits/corrosion)
-insufficient air flow (dirty/blocked fins, fans not pulling)
-insufficient coolant flow (eroded/defective pump)
-low coolant

-You have a how new? Dewits rad, one of the best, so capacity and efficiency should not be a problem. But you should still scan it with your temp gun looking for cool spots.
-Check your voltage on the fans to make sure you are at a minimum of 13v at the fan. Power direct from the alternator is best.
-Fill your expansion tank to the top, and put the cap on. It will puke out what it doesn't want. Make sure there is no air pocket.
-You ordered the best pump available, so that's covered.
Until you receive the pump this is what I would do.

-a serious cooling system flush
-check plugs and carb for too lean condition
-upgrade to a hei distributer with vacuum advance and set it to Lars specs or just short of pinging at all rpms
-check exhaust flapper (restriction)
-make sure front spoiler and foams are in place
-also get or make the spoiler extension

Running 210 at all times is acceptable, but with your components you should be able to keep it under 200.

BTW, the best water to use is dionized, but distilled is next, but it must have the proper parts per million of the sca's for internal corrosion protection and not for freezing in your area.

PM me your email and I'll send you a pdf of the good flush proceedure.

 

Hamid, emailed you the doc.

 

Radiator temp drop's definitely not right, it's almost as if you have a ridiculously slow flow of coolant through the rad, for some reason, like a trickle or none at all.

Is that 2F drop with the fans ON?!? Depending on how much those fans pull, based what I've seen on a newly re-cored STOCK rad for a small block, I'd expect more like 50 or 60F drop in coolant temp. It depends totally on how much coolant is actually flowing through it, but it should be in the "tens" of F somewhere...

 

noonie : can you please double check the sent email? I didnt receive it yet.

theoUK : yes the fans were blowing when I took the measurments. I will try to flush the coolant passages in the engine and see what will come out. Also I am waiting for the stewart water pump to arrive, actually these people driving me crazy! It has been a week and each time I call them they promise they will send it today!! I just dont get it! they got my money, they got the part, they just have to call ups,fedex, what ever and just send it to me!

 

Hamid

Sent it again broken into 3 smaller emails. Maybe because of size or maybe in your filtered junk/spam mail box.



Packages overseas can be a real pain in the butt if you don't do it all the time.

My wife sent care packages to Iraq and Afganistan and had to jump thru hoops even though they were going to an apo in New york first.