For those with 72-74 stock big blocks, what's your normal running temperature ? After a new thermostat and radiator flush my 74 is still around 200-210. With the exeption of headers everything under the hood is stock. Just replaced the old headers with new one's coated with Jet-Hot so am hoping for a bit of improvement. I think the current anti-freeze/water ratio is on the very high end of mostly anti-freeze.

Thanks for your thoughts,
Scott

 

My 73 BB ran around 200 to 210 consistently, unless I had the A/C on in >80 degree weather, then it would overheat. I played around with everything including new, hi-flow water pump, back to a regular water pump (advice said the water was moving too fast, bla, bla), tried water wetter, new hoses, flushed radiator, new fan and clutch, replaced the air dam, changed engine timing, ad nausium.
Then I broke down and bought a Griffin aluminum radiator from Dewitts and it cured the problem. It never runs over about 190 in the hottest weather, standing in traffic with the A/C on. It's really great, now.
The whole problem is that the bow tie boys cut it too close with the radiator size. The original copper/brass radiator only works with a new, efficient engine and clean, efficient water passages in the engine and radiator.
So... you can fart around with all the magic potions and theories you can come up with, but until you get a GOOD radiator, you'll continue to have heat problems.

 

My 74 big-block came under control once I topped off the coolant. I did all the usual stuff too.

Some say that water is a better coolant than antifreeze - you just have the antifreeze for the freeze protection and lubrication/protection of the cooling system.

If you have a sizeable air bubble in your cooling system, the air will compress allowing the temperature to go up - a minor case similar to a busted hose causing an overheating condition. Make sure your cooling system is full of coolant and not 90% coolant and 10% air.

 

Great timing on your question!

http://forums.corvetteforum.com/show....php?t=1032653

Regards,

Jay

 

I run 200-210. It worries me in Hot Houston Texas! I have done most of the aforementioned, water wetter etc. Really we need the DeWitts Radiatior and maybe even an electrical fan for those of us that get stuck in traffic. I am doing it in stages, next is the high flow alum pump from Stewart, never too much flow..IMO. I believe the radiator to be the weak link, but I have not gotten around to that job.

carbster09

the local corvette restoration shop, says my vette is "normal" too! Frustrating...

 

There's nothing wrong with having the temp at 200-210 degrees. That said, put water in your antifreeze! The two need to work together to be effective.

 

I have a 73 454, and the temp runs right at the 200 mark. My A/C does not work, so I dont know what changes that would make to the system. From what I can tell everything is stock under the hood. Fan, fan clutch and radiator.

It looks like 200-210 is what most of the replies have been.

kdf

 

I have a 3 inch aluminum rad, a high flow trw water pump that I run 30% overdrive and twin 16 inch electric fans. I did alot of testing with and without a thermostat. I only drive in the warm weather. I would remove or replace the thermostat each time the car went out to get a feel for what I wanted.
I found that without the thermostat and NO electric fans turned on I could cruise forever and the temp stayed around 180-185. If I entered town I needed 1 fan and if hot stop and go both fans but the temp never climbed past 200, never and cooled right down again as soon as the traffic got moving.

With the thermostat I needed one fan on all the time even with a low temp thermostat. I could not cruise without at least one fan on and the temp was about 190.
I have an accurate aftermarket gage, tried a number of new 160 and 180 thermostats and decide that for me NO thermostat was the best way to go.

 

I agree with all, especially the 73 BB crowd as I have one. Tried everything, radiator cleaning and replacement (motor mount broke and the fan ate the radiator), t-stat, stewart water pump, timing, seals etc. A BB runs at 200-215 even with a 180 t-stat. The only way I can keep it down around 190 - 200 is with a 18" flex fan in hot weather, no fan clutch. Solution - go with a alum radiator and dual electrics like the Dewitt package.

 

Thanks for all the responses guys. Am liking the Dewitt' s idea a lot. Until then I'll double check everything you all mentioned. Great to know I'm not alone!

Thanks

 

As much as I'd like to sell you a package, I don't think you need one. You see water cools a lot better that glycol does and if you are running a high concentration of coolant, that alone could be adding 10-15 degrees or more. I'd run a 50/50 mix, using distilled water. You can now buy this pre-packaged at any auto part store, so you don't have to look for distilled water. It's already done for you. Do that and you will see a drop in temps.
I would caution anyone on the high flow pumps. Every radiator has a unique "peak" point. That means GM found the "peak" point each stock radiator and matched it with a water pump. Many times people add a high flow water pump and it actually makes it run hotter because you exceeded the peak point. Then billybob says the best way to fix overheating is to install a restrictor plate, and it works. Ten other people hear about this success story and they install restrictor plates only to have a different result. The Bs can add up quick and you have to listen very carefully to "testimonials".
I could give two answers to almost every question asked because in most cases the question does not give enough information to answer it. Let's say that in your case you opted to change the stock C/B to one of our aluminum radiators, then asked about a higher flow water pump. My answer would be Yes! It may actually add additional cooling. The reason the answer changed is because the radiator changed. The tubes are larger and to obtain the same turbulant flow, you could benefit from a bigger pump. Do need it? Probably not, but in big time (600plusHP) engines this can make a difference.

 

In Houston weather my 73' 454 always ran 200-210. Changed to Tom Dewitt alm. and 70/30 mix. 180-190(AND THAT'S doing some hard running!

 

I have been involved in this same problem. We now have the 454 in a 72 running about 180 on a hot day, when the cooling system is topped off. Airflow through the radiator and not around it is important. The fan clears the shroud by about 1/4" and if you lean on the shroud while it is running it will touch the fan. No it doesn't touch on torque up, but it gets a little closer.

The timing is also critical. The dist. curve was set, sorry I don't remember the min/max advance #'s.

With airflow and timing I have driven the car at 90+ and temps were about 190. (air temps were 95+)

These were all with the a/c off. With the a/c on it would go to the 210+ in traffic and about 195 at cruise. But consider my C5 hits 225 before the fans come on and it is an all aluminum block with as a design from the factory.

210 is not too bad, if you aren't exceeding it on a hot day.

Wetter water , never did anything but take the $$. This doesn't mean it doesn't work for someone else,, but for us

The water pump,, that too big a pump doesn't help, The water has to have residence time in the radiator to effect heat transfer. If it is too fast it won't exhange the heat.. Best of luck,, 99 Nassau Blue

 

Has anyone had water loss in the 454 with no visable external leakage. We lose about 2 qts/100 miles with the temps running in the 180 mark. The left bank exhaust smokes I suspect a cracked head with the water going out the exhaust as vapor. There are no combustion gasses in the radiator or boil over. Thanks 99 Nassau Blue

 

185° with a 502 in a '70. Stock radiator/clutch fan. Was running 200°+ until I replaced all the seals around the radiator/shroud. Now all the air pulled goes through the radiator.

 

Something else that will help the temps while IDLING and in stop and go traffic is to use manifold vacuum rather than ported. GM must have known something because on my 69BB with A/C the AIM shows a switch from ported to manifold vacuum and I have heard the same thing from other sources as well. Keep in mind that this WILL increase emissions at idle so may not be an acceptable mod if you are in a smog state.

My .02

Regards

Jay