When you click on links to various merchants on this site and make a purchase, this can result in this site earning a commission. Affiliate programs and affiliations include, but are not limited to, the eBay Partner Network.
Have you driven the car on the highway yet? If it's within normal limits on the highway, that would point to a fan clutch problem. A picture of your cooling system would be of help to determine if the seals and shroud are installed properly. Jerry
Jerry,
No I haven’t driven it on the highway yet. I was going to buy a new Fan Clutch Hub so that the fan will spin at engine speed all the time. I think that will replicate it being driven on the highway, except for the fact there is no air blowing over the car. The car did overheat when sitting at a red light, not when I was driving at 45 mph. The outside temp was 72, so nice day.
Tucson has red lights every 1/2 mile. Not classic car friendly.
Where is your vacuum advance hooked up to? As mentioned in the article NOWHERE MAN posted, http://www.camaros.org/pdf/timing101.pdf, it needs to be full time vacuum, not ported.
When you say it gets in the 200 degrees after 20 minutes, is this driving or sitting idling?
What level are you filling the radiator? If an OEM as it sounds like, there are marks a few inches below the fill cap. If too full it will puke.
Don't replace anything....pay close attention to post #3 & #4. I can't say how many times people have blown me off on the timing issue and later said Oh my god you were right. I am not just taking about the intial timing you do from the spec book but rather the "all in" amount and the function of the vacuum advance.
Here's what I would do before spending another dime. 1. Check the gauge/sendig unit function with an IR gun. (if it's way off you are chasing a problem you don't have) 2. If #1 checks out, then check the function of the vacuum advance. (which is super easy to do. Just do your timing (hose plugged) and then reconnect it and see how much the timing jumps up) If you don't see another 12-18 degrees then something is wrong. IE.Bad vacuum can, wrong can, ported vacuum source)
Here is another really easy check that cost zero dollars. Let's say the #2 test did nothing and the vacumm can added nothing or very little. You can simulate it's function by simply turning the timing up to about 25 degrees (do not drive like this). I think you'll see the temperature drop significantly and/or rise lower.
And finally, quit adding more fluid when it pukes out. It's NOT boiling out, it's expanding out. Once that happens you will have a proper fill level and it will never do it again. In order to boil a 50/50 mix, when pressurize to 15lbs, you would have to go to about 270 degrees
I always thought you want a odd number of fan blades to reduce noise.
The thought crossed my mind about fan noise switching out the factory 5 blade fan. I don’t notice any appreciable difference in noise between the factory 5 blade vs 6 blade fan.
The radiator is an aluminum restoration unit with VA installed. The extra air flow helps in city driving.
running the engine with the rad cap off until the t-stat opens up would solve that
Not really comparable, but when my mom's Rodeo had air in it, all it did was blow water out the top of the radiator. I'd fill and it would spit. I ended up pulling the thermostat out and using garden hose pressure to make sure it was full. I put the thermostat back in and it was fine. I know it's apples and oranges. Then again, I had a Thunderbird that did that too. I think it actually had a "burp" valve for that purpose. Been a minute since that car so I don't have total recall.
Don't replace anything....pay close attention to post #3 & #4. I can't say how many times people have blown me off on the timing issue and later said Oh my god you were right. I am not just taking about the intial timing you do from the spec book but rather the "all in" amount and the function of the vacuum advance.
Here's what I would do before spending another dime. 1. Check the gauge/sendig unit function with an IR gun. (if it's way off you are chasing a problem you don't have) 2. If #1 checks out, then check the function of the vacuum advance. (which is super easy to do. Just do your timing (hose plugged) and then reconnect it and see how much the timing jumps up) If you don't see another 12-18 degrees then something is wrong. IE.Bad vacuum can, wrong can, ported vacuum source)
Here is another really easy check that cost zero dollars. Let's say the #2 test did nothing and the vacumm can added nothing or very little. You can simulate it's function by simply turning the timing up to about 25 degrees (do not drive like this). I think you'll see the temperature drop significantly and/or rise lower.
And finally, quit adding more fluid when it pukes out. It's NOT boiling out, it's expanding out. Once that happens you will have a proper fill level and it will never do it again. In order to boil a 50/50 mix, when pressurize to 15lbs, you would have to go to about 270 degrees
Tom,
Thanks for the suggestions. I will try these later today and see what happens. Everything you wrote makes sense.
A bad or not functioning fan clutch could give you these issues. As someone already mentioned put a fan in front of your radiator/front of car, I keep a 24” fan in the garage for this type test. They are cheap, less than $35 at the local hardware or Walmart. Run the fan pointing directly at the radiator on high. If this does not drop temps you have another issue. If this allows the car to run cooler you know your fan clutch is not working. If you really want a fast temp drop while the fan is blowing spray a mist of cool water at the front of the radiator. Your temps should almost instantly drop 25-30 degrees.
These checks are cheap, and they are accurate to help diagnose an overheating issue.
I would advise highly against using the factory fan blade with a spacer or fan clutch eliminator. The factory blades are designed to run with a fan clutch and do not spin engine speed except for very short periods of time. When a fan clutch fan blade spins engine speed they metal fatigue and a fan blade can and will break off. Some people have been killed by this and many have had damage as the fan blade can fly right out through the closed hood.
There are a few types of fan clutches and they do not function the same, a good one can help you and a bad one can leave you in overheating situations. That is another discussion and has been documented on this forum before. If you find it is the fan clutch we can discuss ideas for that.
If the block was sonic tested your .070 oversize would be no issue. I. Know thousands of 454 engines were bored as much as .100 oversize with no issue. My cousin runs a ,100 over 454 in his Motorhome where it works very hard he uses it to tow his race car in a closed trailer with no overheat issue. I can’t say how much is safe with your 427, someone with 427 experience needs to jump in.
A bad or not functioning fan clutch could give you these issues. As someone already mentioned put a fan in front of your radiator/front of car, I keep a 24” fan in the garage for this type test. They are cheap, less than $35 at the local hardware or Walmart. Run the fan pointing directly at the radiator on high. If this does not drop temps you have another issue. If this allows the car to run cooler you know your fan clutch is not working. If you really want a fast temp drop while the fan is blowing spray a mist of cool water at the front of the radiator. Your temps should almost instantly drop 25-30 degrees.
These checks are cheap, and they are accurate to help diagnose an overheating issue.
I would advise highly against using the factory fan blade with a spacer or fan clutch eliminator. The factory blades are designed to run with a fan clutch and do not spin engine speed except for very short periods of time. When a fan clutch fan blade spins engine speed they metal fatigue and a fan blade can and will break off. Some people have been killed by this and many have had damage as the fan blade can fly right out through the closed hood.
There are a few types of fan clutches and they do not function the same, a good one can help you and a bad one can leave you in overheating situations. That is another discussion and has been documented on this forum before. If you find it is the fan clutch we can discuss ideas for that.
If the block was sonic tested your .070 oversize would be no issue. I. Know thousands of 454 engines were bored as much as .100 oversize with no issue. My cousin runs a ,100 over 454 in his Motorhome where it works very hard he uses it to tow his race car in a closed trailer with no overheat issue. I can’t say how much is safe with your 427, someone with 427 experience needs to jump in.
I will try the fan today. Lots of trouble shooting but nothing that is cosmic. I did have the block sonic tested and magnafluxed and they assured me the block is good.
I’ll check in tomorrow and let you all know what I find.
Yesterday the gentlemen restoring my car tried a better more expensive coolant. He ran the car in his garage for 30 minutes at 1400 RPM and the temp never got higher than 220 degrees. So that sounds promising, but today when I go there I will still try some of the things you all recommended.
Here is a picture.
Just nosey, but where in Tucson are you? I am just south in Green Valley. What shop(s) has your car been in?
I live up north in the Foothills. I have not taken the actual car anywhere except to an alignment shop after we were done. I used Gary’s Machine shop for my engine, Western Differential & Driveline to rebuild the differential, and Performance Radiator, plus a few more shops for other things. I sent my water pump to a place in Phoenix, and my restorer has done the rest.
Yesterday the gentlemen restoring my car tried a better more expensive coolant. He ran the car in his garage for 30 minutes at 1400 RPM and the temp never got higher than 220 degrees. So that sounds promising, but today when I go there I will still try some of the things you all recommended.
Here is a picture.
It sounds like you have received a lot of good advice on your cooling issue. I'm in the fan clutch camp with several of the others.
My comment is more towards what I see in this picture. At 1500RPM, I'd expect the OP to be higher then what it is showing, especially on a fresh rebuild. You may want to try an external gauge to verify the pressure.
Good luck with your hunting and keep on keeping us updated - useful info.
Base timing of 6 degrees advanced is insufficient today and most would label as retarded timing. Yes, the manufacturer built them that way back then but they ran better (and cooler) with more base timing. I would try it with 12 degrees if you can keep base timing and max centrifugal advance to around 36 degrees. Vacuum advance needs to be “T’d” into the choke break vacuum hose from the manifold vacuum source.
But this probably isn’t the total issue so it’s good to keep looking.
So I ran a box fan directly in front of the radiator while the engine was running and it did not drop the temperature. We did add VP Racing MADDITIVE Cool Down to the coolant and the temp peaked at 220, which is what you see in the above picture that I posted.
Still more troubleshooting to do and I am still considering changing the timing from 6 degrees as it has been recommended.
11-01-2023, 02:09 PM
