Like many I have been fighting high temps in my '65 L79. I have a DeWitts radiator, I tried different thermostats, fans, timing, etc. I ran across this article about adjusting fan clutches and I was completely amazed with the results. My fan clutch is an AC Delco from my local auto parts store and its the thermostatic kind. If you have a similar clutch and your fighting high temps this fix takes about 30 seconds and my car ran about 45 degrees cooler!!

http://www.stl-vettes.com/65Vette/co...tch_Adjust.pdf

 

Thanks for the tip. I jsut put Vintage A/c in my 66 327 and can notr seem to get the temp under 210. I put an aux fan on, changed the thermostat to 160 degrees, flushed the radiator,added new antifreeze. I was just about ready to change ther radiator until I found your post. I'll give it a try this week and post my results..

Thanks George

 

Very interesting article.....gotta save this one. Thanks.

 

Excellent article! Thanks

 

George, I would change that thermostat back to at least 180º. First of all the thermostat doesn't control the high temps, it controls the low temps and your engine won't run hot enough to remove moisture from the oil if you were ever to fix your over heating problem.

 

Typo: meant to type 45 degrees....not 15. I still cant believe this simple adjustment worked so well.

 

An aluminum radiator should help, but try the fan clutch trick first...much cheaper! Im running a 160 thermostat but I have an aluminum radiator, which is much more efficient than copper. The idea is that the coolant stays in the radiator longer with a higher temp thermostat, but I believe since the alum radiator is more efficient you can run a cooler thermostat. Im still playing around with thermostats.

 

I run a 160 thermostat with a stock radiator with absolutely no high temperature problems at all. I had my car out yesterday with mid 80 degree temperatures and it ran cool all day long.

 

yep......

 

Great article and perfect timing!!! I’m also fighting with 210* and new Vintage Air. I’m currently running the stock 5-blane fan. I was about to go and add on a 7-blade fan. Do I need to, what are you running?

Joe

 

Joe, Im currently running a stock 5-blade fan, although I just ordered a 17" 6-blade fan from Jegs (see link). I'm not expecting huge results but its only $40 and looks kinda stock. I will let you know the results.

http://www.jegs.com/i/Flex-a-lite/400/5717/10002/-1

 

Wow...does look cool.... Keep us posted on how you make out with this....

 

Hope you enjoy the harmonics (woooow, wooow, wooow) There's a reason that GM used an odd number of blades and did not space them equally.

Just my opinion and experience.

 

Good article, thanks for sharing that.

My 64 also L79, had a 7 blade fan in it when I got it. It ran cool, but I went back to the original 5 blade for a stock appearance and noticed no increase in temps at all. With that said, all the fan seals are in place, stock aluminum radiator, rebuilt water pump, and North East operating environment. Pilot Dan

 

Could you explain to me how this works?

 

This I've got to hear.

 

go to a 180º t-stat. it's what was installed at the factory as correct and is still the correct one to use today. The t-stat will NOT determine operating temp, only at what point the MINIMUM operating temp will be.
If all things were perfect the cooling system should be able to keep operating temps right about where the t-stat rating is so if that were the case and you have a 160º t-stat in there and the operating temps were actually 160º that's too low of an ideal operating temp and you run the risk of sludge build-up in the oil plus you are greatly increasing cylinder bore wear

BTW, A higher rated t-stat does not make the coolant stay in the radiator longer. Well it does until the motor comes up to temp, than the t-stat opens up. Once the t-stat opens up it's not making the coolant stay in the radiator longer or shorter periods of time depending on the rated temp and even if it did it wouldn't make a difference anyway.
Let's just say for arguments sake that a higher rated t-stat actually did allow the coolant to stay in the radiator longer (which it really doesn't) than think about what's happening.
It's a CLOSED system so if the coolant flow were slowed down to allow the coolant to stay in the radiator longer it would allow more time for the radiator or cool the coolant and reduce the coolant temp.... BUT at the same time in the other half of the system the other coolant is also allowed to stay in the hot engine block longer, picking up more heat. Therefore it would NEED to have that additional time in the radiator to eliminate that excess heat the coolant picked up.
Less time the coolant stays in the block means less time is needed for it to stay in the radiator, while more time the coolant stays in the block the more time it needs in the radiator. Remember- closed system.

The idea that an aluminum radiator is more efficient is true - typically an aluminum unit has about 30% better cooling capacity over a copper/brass unit, but that doesn't mean that you run a lower rated t-stat in the system, it only means that an aluminum unit has better cooling capacity.

 

No argument with anything said, but totally removing the thermostat on some cars will cause overheating. If you remove the thermostat, you have to run a restrictor to slow down the rate of coolant flow for proper cooling.

Or so I'm told . . . . .

(I know, it's counter intuitive.)

 

couldn't tell you either way since I don't run my cars without the t-stat. The t-stat is suppose to be in the system so it is on my cars.

A t-stat does introduce into the system a calibrated restriction to make sure the coolant flow is at the correct flow rate as per the systems design parameters, but totally removing it from the system, while allowing coolant flow to increase somewhat, really shouldn't cause an overheating condition - assuming the rest of the system is operating correctly.

 

I agree, your right here...I was not so clear. The thermostat allows the engine to come up to normal operating temp faster, which protects from damage to cylinder walls etc. during cold idling. So a higher temp thermostat will keep the coolant in the radiator longer (before it opens). I live in central TX and its been 100-104 degrees outside. My engine has no problem coming up to normal temps with the 160 dgree thermostat. In the fall I will likely change it back to 180*. The reason I installed a 160 stat is because when I was fighting an overheating issue my 180* thermostat was opening at 180 and then the car would quickly overheat. So I put the 160* stat in to slow the overheating process and buy myself some time to diagnose the problem(s). As mentioned, my engine comes up to normal temps in just a few mins, so Im not too worried about changing the thermostat. In the winter with cooler air I will change it. Opinions?