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Old 08-28-2009, 11:54 AM
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Engine runs hot at highway speed.

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

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Old 08-28-2009, 12:17 PM
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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.
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Old 08-28-2009, 12:33 PM
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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
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Old 08-28-2009, 12:52 PM
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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

Last edited by dawg; 08-28-2009 at 12:59 PM.
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Old 08-28-2009, 01:17 PM
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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
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Old 08-28-2009, 01:26 PM
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Are you running a vacuum advance on this motor, and if so how is it hooked up?? Manifold vacuum or ported vacuum??
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Old 08-28-2009, 01:29 PM
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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
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Old 08-28-2009, 01:33 PM
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Quote:
Originally Posted by ericnova72
Are you running a vacuum advance on this motor, and if so how is it hooked up?? Manifold vacuum or ported vacuum??

Again I am just learning. I have some outside help. The vac is hooked up to the back of the carb. It is a holly 750. Did I answer the question??


Kirk
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Old 08-28-2009, 01:40 PM
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Quote:
Originally Posted by kirkschopped67
Again I am just learning. I have some outside help. The vac is hooked up to the back of the carb. It is a holly 750. Did I answer the question??


Kirk
So the vacuum to the distributor is hooked to full manifold vacuum?? Just verifying.
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Old 08-28-2009, 01:41 PM
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Yes it is.
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Old 08-28-2009, 01:43 PM
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Quote:
Originally Posted by kirkschopped67
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
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
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Old 08-28-2009, 02:13 PM
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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
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Old 08-28-2009, 02:32 PM
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Running hot at highway speed is indicative of a radiator problem ( discounting an engine problem) . Either it's too small or air flow through it is insufficient. Perhaps your electic fans are restricting air flow too much.

Vince
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Old 08-28-2009, 02:43 PM
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That is a possibility. I will check it tonight. I have made notes of all the suggestions and I will keep everyone informed of the end result. This is how we learn.

Kirk
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Old 08-28-2009, 03:39 PM
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Quote:
Originally Posted by kirkschopped67
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
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

Last edited by dawg; 08-28-2009 at 03:44 PM.
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