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Engine runs hot at highway speed.

17K views 23 replies 11 participants last post by  RWENUTS 
#1 ·
I know this topic has been beat to death. I have research this site and read a lot about the subject.

I have a big block 460 ford crate motor that has just been broke in. I have Dakota Digital gauges and in town under 30 mph w/electric fans running the temp moves between 195 and 210. As soon as I take it out on the highway, (55mph) the temps quickly begins to rise to 225. Last night going up the hill to a car show ( 1000 ft elevation) the temp quickly hit 231. Once I came back down the hill the temp still wanted to stay at 218. I was hard to keep running at a stop light. Can you give me a list from first to last of things to check and what might be the problem.

Electric fuel pump
750 holley carb
gear drive
cobra jet heads
Aluminum Radiator from BeCool
MSD electronic Ignition
Cool Flex hoses



I need help so I do not ruin this motor.

Thanks
Kirk :D
 
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#2 ·
Have you checked your spark plugs to see if the carb is jetted correctly for you application?
Lean mixture(or incorrect timng) under heavy load will create more heat.

One thing you dont mention is whether the radiator is sized correctly for this motor. Is this in an original BB car, or is it a swap and youre still using the SB radiator, this could cause the running hot too.
 
#3 ·
This is a Big Block truck. The motor is an upgrade from a 352- to a 460. But I purchased a BeCool radiator that is to cool a 700 hp motor. This motor is 520 hp. I have a friend coming over tonight to check the timing and he also talked about the jetting in the carb. I believe you are right on. The motor does not run as I thought it might. I do like to hear what you car guys have to say. I am just learning and I am very interested in how all this stuff works. If you have more ideas, please let me know. When I find this problem, I will post here the results so others can read and learn what cured the issue.

Thanks
Kirk :welcome:
 
#4 · (Edited)
ya might try a lower T stat at 180 degrees.
if your running without a thermostat thats a big NO NO.
and without seeing your setup im guessing the fans dont have a full shroud?

also is the radiators front side sealed to prevent air from going around radiator instead of through it? (youll be suprized on how great it works)
is your rad cap good?
a 12 to 15 psi should help.
one last thing to check is lower radiator hose.
look at it when you goose throttle.
if the inner spring is missing or the rad hose isnt the reinforced type it will suck itself closed causing high temps.
cool flex hoses (corrigated tubes) are not the best thing btw they tend to break apart.
one last thing is belt tension on the water pump
 
#5 ·
I did install a 180 degree hi flow t-stat and it did not help. This morning I did take out the t-stat and I was going to run it tonight to see if that was restricting the flow to much. The cap and radiator are brand new. I believe that BeCool would have sent the correct cap, but I now need to check. The lower radiator hose is brand new. This is a fresh build; only two months old. I will watch the hoses. I paid a lot of money if they fail the guys at cool flex will have a hard time pulling them out_____. The belt tension; I have a Billet specialties from end on that motor. It has a tension device on it that I believe is spring loaded. I will check all that we talked about, if you think of anything else please let me know.

I did read some of your past responses on other posts, good stuff
Thanks
Kirk :confused:
 
#11 ·
kirkschopped67 said:
I know this topic has been beat to death. I have research this site and read a lot about the subject.

I have a big block 460 ford crate motor that has just been broke in. I have Dakota Digital gauges and in town under 30 mph w/electric fans running the temp moves between 195 and 210. As soon as I take it out on the highway, (55mph) the temps quickly begins to rise to 225. Last night going up the hill to a car show ( 1000 ft elevation) the temp quickly hit 231. Once I came back down the hill the temp still wanted to stay at 218. I was hard to keep running at a stop light. Can you give me a list from first to last of things to check and what might be the problem.

Electric fuel pump
750 holley carb
gear drive
cobra jet heads
Aluminum Radiator from BeCool
MSD electronic Ignition
Cool Flex hoses



I need help so I do not ruin this motor.

Thanks
Kirk :D
Typical of not enough radiator, to a lesser extent lean mixture, retarded timing of either or both cam and distributor.

What is this engine installed to? Many custom installations in classic 1920s thru early 1940s bodies have trouble flowing enough air thru the core at speed. Especially prevalent with open hood installations where the air flow finds it easier to go around the radiator core than thru it, this problem only gets worse as speed goes up and mysteriously goes away at idle when the fans are effective.

My first guess would be the aluminum radiator is either insufficient in size or has an inability to keep air passing thru it as speeds go up.

Bogie
 
#12 ·
The truck is a 67 ford pickup. The radiator should cool up to 700 hp. It is from BeCool. The front of those trucks can except a lot of air flow. In town at slower speeds I run the fans, and it runs around 200. As soon as I run it at 50-60 mph the temp starts to climb. I manually keep the fans on and I have shut them off, and there is no change. I am beginning to think this is a timing problem. I will set the timing tonight and check the plugs for how lean it is running.

Running without the t-stat??

Kirk
 
#15 · (Edited)
kirkschopped67 said:
You said; running without a t-stat in a BIG NO NO. I believe what you are saying; but what effect does it have in the end. I know now it can not be good. I am just trying to learn.


Kirk :sweat:
the T stat does two functions
1. it gets engine up to operating temp faster
2.it also acts as a restrictor of sorts.
if coolant flows too fast it wont absorb the heat effectivly.
you can also have a faulty thermostat.
I cant remember how many I took back for not opening all the way.
I would test it in boling water to see if it opens fully.
but i suspect that your fans dont have a good shroud.
but alas ol DAWG knows where to get good one fairly cheap.
check them out here.
http://www.coolcraft.com/shrouds.html
 
#17 ·
Yes here are the updates. The first thing is the timing was retarded. I advanced the timing and the temp started to fall with in a minute or so. On the highway it was over 230 degrees. It dropped down to 212 degrees. Still not happy with the results; I did a spark plug test. I ran the truck at 35 mph for a 1/2 mile and shut the engine off and coasted to a stop. Right there I pulled a plug from each side and found that it was still running to lean. I made an appointment to take it in to a Hot Rod shop where I live to have the jets changed. Out of the box there is no way that all these parts are going the be able to work together without being adjusted.

I did go to a car show this weekend. I had to set in line for about an hour. The temp stayed at 183 degrees and it was 102 outside. Advancing the timing really helped. I will have it tuned and I believe it will solve a lot of problems

Thanks for the help, I needed it.

Kirk :D
 
#19 ·
I had pulled out the t-stat that morning, but I did not run it. Someone knew what I was thinking. So that night I went and reinstalled the t-stat. I figured that the t-stat was not the problem and It would not fix it . The timing and the jets in to be adjusted to work together.

Kirk :cool:
 
#20 ·
Less tha 13volts at the battery really screws up the gage readings as well.

low voltage/bad connection will show a high temp (in my case 30*)
It will also cause a low oil pressure reading (as much as 20#)

I spent 2 years beating on an overheat condition that was really just a bad alternator.

My 454 in the 59 ---base timing at 18*
 
#21 ·
sunsetdart said:
Running without a t-stat with a water based coolant is a no-no, ...reason why is that a water based coolant needs to develop pressure for it to work properly. Without the t-stat the system does not get up to the correct pressure.

Not exactly. Even without the t-stat, pressure will develop. The reason for pressure ais basically to crank up the boiling point of the coolant's water base. For every 1 psi pressure increase, the boiling point goes up 3.25 *F. What running without a t-stat does is allows too much flow through both the rad and the engine. This prevents heat saturation of the coolant. The coolant does not stay in contact with the heat bearing areas of the engine long enough to absorb enough heat energy, and then does not stay in the rad long enough to transfer any heat energy to the airflow through the core. This causes a compounded effect of some heat removed from the engine, but not enough released to atmosphere. You then end up with overheat, as well as localized hot spots in the engine.
 
#22 ·
sbchevfreak's


Thank you for the post. I did not know how it works. I now understand why we need t-stats now. I am going in for a tune-up at a local hot rod shop. I will post the out come and how well the truck performs.

I am having second thoughts on the torque converter that was chosen for me. I will post about that later today, because I do not believe this application is correct for the driving I want to do.

Kirk :D
 
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