doorgunner

EDIT: I thought I had the problem solved, but it seems like I have only postponed the overheating (which means I'm headed in the right direction)

I'm STILL dealing with the overheating issue in spite of everything I've done.....all the solutions have helped the overheating----but have not SOLVED the problem......even at 50*F ambient air in town at 35 mph or highway at 60mph for 1 hour...timing set at 8*BTDC....engine idles great/runs great....(EDIT--but cranks slowly after overheating/cranks strong once the engine cools down).......but the temp holds at 210* (which is better than the continous boiling-over every 20 minutes that I've been dealing with.

180* thermostat (again).....

Radiator is cleaned/flushed/burped ......

Heater core is cleaned/flushed/burped......

New 50/50 coolant AND Lucas coolant temperature reducing additive...

New hoses...

Foam rubber seals installed around radiator....

New water pump (previous pump had long rust stain at drain hole...

EDIT: Rebuit electronics in HEI Tach-drive distributor



Here's the latest thing I've discovered---It's probably been like this the whole time/I just didn't notice it.

The upper radiator hose is nice and flexible with the engine OFF.

Once I start the engine and the car warms up....I literally CANNOT squeeze the top radiator hose AT ALL/NOT EVEN A DENT! (I could understand that it might be stiff if I had a 15 lb. radiator cap installed!)

I'm using an 11 lb. radiator cap to keep from rupturing the 45 year old radiator.

The radiator doesn't have any tubes pinched/soldered shut......Am I on the right track in thinking that it may be nearly stopped up and restricting the coolant flow into the engine?


HELP!!!! GIVE ME A NEW LIST/YOUR THOUGHTS ON POSSIBLE CAUSES (AGAIN LOL)

jr73

I'll get out my stack of magazines and search for answers

76CSRvette

Does it still over heat with out thermostat.
what if you cut out the heater core and do bypass to int manifold.
stupid question but what way is thermostat facing.
210 is not bad as long as its constant that is my high spot my 200-210 while my old 327 never got above 180.
Do you have the front air dam installed.
and how is seal at the top of raddy and seal on top of support.

doorgunner

Thanks for quizzing me....I'm wondering if that "hard upper hose" is the sign of a bigger problem?

Would moving the ported timing from 8* to 12* help prevent overheating?

llj20024

Defective water pump impeller or the lower radiator hose is collapsing.

76CSRvette

Im looking into installing aluminum tubes i saw from speedway motors they have a 6in pipe the 1.75 to 2in diameter and cut up original hose and put in middle just to avoid the collapsing even though mine doesn't do it anymore just for piece of mind and looks also plan on doing top and polishing. U can try and play with timing i still do it just mark where u have it and mark 10 and 12. I tried switching from ported and stock but for me what drives good in the day i struggle for night so i played with it back and forth. maybe a little advance could help. Do you have the hei im assuming or old school dizzy with coil. Just wondering

doorgunner

I will put a large piece of cardboard over the front of the radiator/remove the upper hose at the rad. inlet/start the engine/let it get to operating temp faster (with the cardboard blocking the air)/when the thermostat opens---the water should fly about 10 feet out of the hose until the radiator is empty.....this will prove the thermostat is working----the impeller is O.K.-----the new pump IS NOT a reverse flow pump. As for the lower hose----I bought a H.D. generic hose that has a thick/non-collapsible internal spring to make sure.



Thanks men---I'll try your suggestions again (I forgot to prove the impeller rotation was correct the last time I posted the overheating thread).

While I have the top hose aloose, I'll stick a water hose in the radiator/seal the inlet airtight with thick foamrubber and turn the hose wide-open to feel the tubes/verify good flow is reaching the engine if the radiator is flowing freely to the engine.

REELAV8R

210* is not bad. Will it hold that or does it continue to creep up?

On my 77 I did everything under the sun to keep the temps down and each thing I did helped. But like you, I was still not happy with the end results. The temps would still creep up at cruise speeds.

The only thing that fixed it was replacing the radiator. Cleaning flushing over and over did not/could not get the radiator clean enough to restore it's ability to dissipate the heat. So that may be where you are at. New radiator. I went with Dewitts aluminum. Once installed no problems. Temps under control at cruise now. Having the old radiator rodded out would have cost more than I paid for a new radiator or I would have also tried that.

Also IMO 8* BTDC is not enough timing to run cool. Wouldn't go any less than 10* and probably more like 12* to 14*. Depends on what cam you got.
Use manifold vacuum as well. Ported vac is going to retard the timing at idle and make it run hotter. Ported timing is an emissions reducing effort, not a performance one.
I currently run 19* of initial timing with a cam with 54* of overlap and use manifold vacuum. At idle with vac attached I have 36* of timing advance.

BKbroiler

I think you're overdue for a new radiator. I put a brass/copper stock type , for L82 (4 row), in my 77 and did everything else you did and I never have a cooling problem.

Mike Ward

Get rid of the ported timing- that's an emissions thing only.

Do you see flow in the rad with the cap off?

doorgunner

You guys!

Mike W.......rookie me.....I went to manifold vacuum...It idled like a new engine....then it started all the weird stuff of stalling/hard starting/etc.

I assumed going to manifold vacuum was causing all the stalling/stumbling. You guys kept telling me to check the ignition....I finally tested the distributor and found bad readings on the electronics/replaced the bad stuff. I also switched back to ported vacuum

Now I realize what you guys are talking about. It's going back to manifold vacuum/reset timing also!

As for the coolant flow.......rookie me I ASSUMED that SOME coolant flow was ENOUGH coolant flow. I checked the coolant flow in my SBC 350 street truck radiator/it looks like the Colorado rapids in the radiator when the thermostat opens----and NEVER OVERHEATS!

The coolant flow in the expansion tank (it's still got one!)is minimal compared to the street truck.....now that makes me think that the stiff upper radiator hose on the Vette/reduced circulation in the expansion tank/creeping overheating..........represents what you guys said---- a stuffed radiator that won't let the coolant pass through at the correct rate!

ANNNNNNNNNND.....THE NEW E-FAN arrived this afternoon (remember....I'm going electric because Bubba threw all the original cooling stuff away)

Thanks Men!

The13Bats

I would look at air flow but I had a 66 that did this same thing, the radiator looked okay but was spent inside it, new radiator cured the problem,
But keep in mind also that you must had enough air flow through the radiator be sure what ever fan you use will move enough CFM of air,

jr73

Everything I've read on these boards tells me aluminum radiators will cure stubborn cooling problems. But BK put on a stock brass/copper type and cures cooling problems as well.
So what is it?
Aluminium is the cure or any new radiator even stock type does the same thing?

doorgunner

That's why I'm spending the time working with modifications......so I can increase airflow/cooler air/air dedicated to each component.....radiator by itself/engine by itself/carb by itself.

The radiator that is now in there might be for the original 327 SBC....I'm with you guys on a new radiator!

qwank

bingo

Mike Ward

You're catching on!

The13Bats

Lots of voodoo and ego chest thumping on radiators and no, a "stock" radiator will not always be the answer each and every time because no two cases or cars are just alike.

I ran 4 core stock type in both my 81's and they cooled okay only creeping up when stuck in traffic on a hot orlando day, added electric pusher fan helped that.
Then my 66 a stick car with no options a stock radiator kept it cool with a Fiero electric fan,

Now I'm running a mild lol 454 with auto trans, and adding AC, also going to run a dual electric fan set up, ( okay, so I am not always old school )
I could have bought new stock BB radiator and hoped it never creeped up too high on a hot nasty traffic day but why take the risk of ruining my day and worse the engine etc?

I did my homework on radiators and yeah, I bought Dewitts, did it cost more? yeah, and I'm cheap but the peace of mind and zero guessing is worth it to me,
when my car is going IF it overheats all I need to do is call Tom and I know the man will do what it takes to cool my car, but that is moot because history and experience proves Tom knows his stuff and my car will run cool. no guessing.

On the other hand if I had a stock or near stock car I still wouldn't buy a stock brass/copper type because the import aluminum ones have gotten so cheap, sure they are not the work of art that Tom makes but some people do not need what I needed ( or wanted ).

Point is if the rest of the cooling system is all okay and the radiator is old or unknown then most of the time any new unit will fix it but that doesn't mean you can't upgrade to aluminum.

BKbroiler

For the most part, these cars had copper/brass radiators when new, and no cooling problems. Of course aluminum transfers heat better than copper/brass, but how well will a cheap aluminum rad fit in the car? If that bottom hose connection is located wrong, you've got a big problem. My point is, if everything else in your cooling system is right, you don't need an aluminum radiator.

The13Bats

In some cases in some places even the stock cooling system was marginal, and vettes do tend to run hot.
With a bone stock set up you might not "need" aluminum well, hell some cars came with Aluminum, oh dang, but sure the stock radiator will work in stock cars.
My point was when some of us start modding for more HP or things like AC or both a better radiator is a must, some people do not want to pay for the top names so I also included the fact that the price of the "cheap" aluminum ones makes it pretty easy to go to the better aluminum over brass/copper,
Hose connectors? well you made a great point why to buy a trusted brand like Dewitts who get it right over a cheap one that "might" fit...

REELAV8R

When new these cars did not necesarily need better cooling. The heat did serve a purpose. It aided in atomization of fuel on cold running engines, since water does run through the intake manifold. It provided heat to the cabin quicker. It may have aided in better emissions in the same way that retarding the timing does. It helped to reduce wear on the engine by bringing all that cast iron up to temp sooner despite the cooling fans continual operation (mechanical fan).
So the original installation may have served several purposes. However as The13Bats has pointed out, your goals may differ from GM's in this area.
My goal is to reduce the heat in the engine as much as possible while still allowing it to come up to temperature quickly on cold starts. I want relatively cool water in my aluminum intake. This will reduce the pre-heating of the fuel/air intake charge to the engine. This allows me to run lower octane fuel and higher CR without encountering detonation.
I have no concerns with it running at 15*F. GM had to make it run in extreme cold as well as hot days.
I want the transmission fluid on my TH-350 to run as cool as possible. So cooler water is cooler trans fluid.
And Dewitts is a made in USA product of excellent quality with a manufacturer who stands behind his product. My direct replacement radiator from Zips made by Dewitts fit perfectly and cost no more than a stock replacement brass radiator.
GM continued to add extras, like A/C, retarding timing , emmisions control and weight, without changing the design of the cooling system. To do so would have required a change. Changes cost more money. If it works good enough then use it. They had no fear from foreign competition yet at that time. GM was a big dog on the street, if it was good enough and cheap enough then so be it.

The aluminum radiator weighs much less than the copper/brass radiator, making it much easier to wrestle around for installation and lightening the overweight C3.
Aluminum is very picky about using distilled water to prevent corrosion, but so are the aluminum heads and intake.
I'm sure a copper/brass radiator would work fine as well, however for those hot slow moving traffic days a little more cooling capacity in aluminum or copper is nice, especially while running the A/C at the same time.

Basically, if you need to replace it anyhow, choose one that fits your goals.