I am trying to decide what to to next to resolve my high coolant temperature problems.

It has been hitting 105 F around here lately and my coolant temperatures are getting up to 220 to 230 F.

I have a 79 f150 4x4 3.50 gears and 35" tires, c6 trans with oem tranny cooler. I have a 3 row super cooling radiator that is about 13 years old and it is free of obstructions inside and out. The factory AC condenser is fairly new and clean. I have a standard 180 degree thermostat and edelbrock water pump. Radiator cap is rated for 13 psi. Coolant mix is rated for 255 F according to tester. I have the correct fan shroud with a mechanical fan and severe duty thermal clutch and it will hold a piece of paper against the grill at idle. I have checked my air fuel ratio with a wide band gauge and have concluded I am not running lean. The leanest I get is at cruise at about 35 mph where i am at 1500 rpm and a AFR of 15. On flat roads at 75 mph I get as high as 15 again. Also checked timing, running 12 deg initial and 36 total in at 4000 rpm without vacuum advance. With vacuum advance hooked up(full manifold 15" at idle) I am getting 12 degrees initial and 38 at 4000 rpm.

It is getting hot without the AC on and it overheats quicker as expected with the AC. I feel I have ruled out the common causes. Timing is not too advanced, fuel ratio is not too lean, cooling fan is working properly to its abilities. Overheating occurs at high and low speeds. Yes it is abnormally hot out, normally the coolant temperature is at 190 with my mechanical gauge when it is about 80 or less outside. I am also experiencing vapor lock occasionally. My edelbrock performer intake manifold has restricted exhaust crossover passages (5/16" hole). I have a phenolic carb spacer and a holley style road demon carb which is less prone to boiling fuel.

What do I do next???

My thoughts are that my radiator needs replaced or re-cored to a 4 row. Maybe wrap my exhaust and insulate fuel lines. I have considered an electric fan but feel more comfortable with a mechanical clutch fan and I have very little room for an electric fan with the radiator engine combo. Will I see a difference with a 4 row copper brass radiator or is it to be expected with these older trucks operating in temps over 100 F?

 

You would be surprised how plugged on the inside and inefficient your radiator might be.
You've covered all the basics. My votes on the radiator.

 

Here is the inside of the radiator. Engine should be good since it was hot tanked and flushed well prior to rebuild a couple years ago.

Also wondering if my exhaust is too close to the oil pan?

 

I really don't think 220-230 is that bad.
You could always switch to a different t-stat so it doesn't start building heat as quick.
Insulate any fuel lines if you haven't already.
A iron block doesn't help with dissipating heat much though and over 100 running AC is tough on anything. It sounds to me like you have most bases covered.
How old is the water pump? Maybe the impeller is worn and not moving as much water as before?

 

I would try putting in a 195 degree thermostat. My 79 bronco had the same symptoms a few months ago. The radiator looked good, flushed about a year earlier so I thought I would try this before replacing the radiator. I replaced the 180* thermostat with a 195 and everything is good now. Sounds like its worth a try...?

If you have ruled out the radiator for sure, then I would look at the water pump next. Remove the radiator cap prior to starting, then start it up and wait for 3-5mins. Look into the radiator cap to see if the water/coolant is moving. You should see the water/coolant swirling.

 

The water pump was good and replaced when motor was rebuilt 2 years ago. I tried a 195 at that time it ran too hot. Is it possible the radiator scale is too much? I'm am thinking of getting a new 4 row.

 

Looks to be a bit of mineral deposit coating in there. That stuff coats the inside of everything including the tubes, and definitely inhibits heat transfer efficiency.

I just cleaned out the old radiator from my truck which was very similar to yours, used about a gallon of CLR (straight, not diluted) to do it. You have to remove the radiator, seal up the upper & lower hose nipples, and dump in the CLR then put the radiator cap on. I sloshed it around for 10 minutes or so then let it sit face down for about a day or so. Came back every couple hours and sloshed it all around again.

Flush it out generously with water after that, then mix up a baking soda/water solution and do the same thing you did with the CLR with that, except it only needs to sit for an hour or so. Flush it out a few more times with water, and it should be looking like brand new copper on the inside.

Never mind what the internet says about CLR, it's all b/s. You could always take your radiator to a radiator shop and have them clean/boil/flush it as an alternative.

 

In my experiences if you can see any coating on the tubes from the filler neck it's starting to plug. A good rad shop would be able to repair it but nothing beats a new rad. Maybe aluminum??

 

After some research I am wondering if my timing is too retarded, which causes high cylinder head and exhaust temps. Anybody have experience with that problem?

 

Only you could know if the timing is off or not. Since 460 wasn't original to that truck we don't know what it came out of. and if the chain was replaced or not
such as
googling shows this
The 1974 460 engines had their base timing set to 14* BTDC from the factory.
The base timing on the 1975 460 engines (in the 49 states of the U.S.A.) was set to 10* BTDC from the factory and it was set to 14* BTDC on the california 460 Engines.
Pre-72 is different as well

 

Ok 14 degrees is interesting. I was thinking to try advancing initial to 14* and turn up the vacuum advance. I seem to recall in past tuning sessions that the vacuum advance was much more than it is right now. I am also going to insulate my fuel lines and try to clean my radiator with CLR or Limeaway followed with baking soda. Also going to check to make sure my return radiator hose has a spring in it to prevent collapse and measure inlet outlet temps on the radiator.

The motor is not stock anymore. It was a 76 california emissions which google says was set at 14*. I do have a straight up pre 71' timing set that was replaced during the rebuild.

Thanks for all the input.

 

FWIW, in case you didn't know 460ford.com is a great resource for you...lots of built 460's with great knowledge!!

 

Yes agreed, I have gotten alot of info from there.

I made the timing changes and checked for detonation. Decided on not flushing the radiator. No vapor lock after insulating fuel lines. Truck runs much better but still reaching 220 to 230 on the interstate and its only 95 today. Getting a 4 row ordered now.

 

Adjusting the timing may help... the engine runs more efficiently and cooler with correct timing. To much, especially with high temps, may cause detonation and other problems (costly).

My vote is the radiator also, especially since it is hot at speed. 13 years old is a lot for a replacement radiator. I ran a newer parts store 3 core on my '78 (400) and it was running warm at speed or pulling in hot weather.

I put a 4 row Champion AL radiator in and problem solved. It runs right above stat temperature at speed and holds it well at idle. 3 row may have been enough but I did not want to do it twice. The 4 row needs a good fan... which you have.

 

I ordered a Murray 4 row super cooling replacement from O'Reillys. Its an aluminum core with plastic tanks-not thrilled and seems cheap, but for 250 I will try it out. Radiator shop quoted me 400 to 800 to recore with copper if he could find it. I really like the looks of the champion but they don't have the 24" height. My hoses are new and I already have the shroud for the bigger core.