You are probably better off getting an electric pusher fan and running it to a switch in the cab so you can turn it on when you are getting to the hills. I missed if you said if the motor had been rebuilt, but if it has, they tend to warm up once you bore the block over .030"

 

if properly designed to do so...but there is the unescaping fact that a sway bar makes a difference, and without one there is a greater cause for mishap...

jus my personal perception...not necessarily a truth... how could a sway bar be anything but a benefit??? I understand that there are special applications.

WICK246- if you dont get an electric fan setup, my choice would be to install a fixed fan(no clutch mechanism)...when does the clutch mechanism actually disengage? is it temperature controlled?

 

Clutch fans are temperature controlled, they use a really phony temperature sensitive metal coil similar to a thermostat on your wall.


Sway bars are optional, they don't make a vehicle safer, they only reduce perceived body roll and attempt to hold back axle hop.

My view on the electric pusher fan is only because you don't have any problems around town or even the highway except for the hills.

 

I have been wondering about this. Overheating at low speeds is usually due to lack of air flow through the radiator. For this reason you need a good fan and shroud. An electric fan is also a good way to provide air flow, when the vehicle is at low speed.

At highway speed, there should be ample air flow. Thermostatic fans will cut off when the air flow is sufficient to cool the motor.

If the motor overheats at highway speeds, it is probably not due to the air flow, but to water flow or to load. That is the cooling capacity of the cooling system is not sufficient to get rid of the heat produced by the motor.

Since you have replaced the water pump, and checked the cooling system for blockage, your water flow should be OK. However there are a couple of things that you may have overlooked.

Is there a spring in your bottom radiator hose? At high RPMs when the water flow is near maximum, the bottom radiator hose can collapse and cause a blockage. It is necessary to have a spring in the bottom hose to prevent this.

Do you have a thermostat in the motor. It is possible to have too much water flow and the heat will not be transferred to the cooling system. I don't think that this applies here, but I thought that I would mention it.

The next is load. Since you are in Montana, you must climb some big hills. Is your motor laboring at Wide Open Throttle for long stretches of highway? Does the water temperature climb at this time? Does the water temperature drop going down hill or on level highway? This is simply a capacity problem. You need a larger radiator. A four row may help, if you don't have one already.

 

Actually I'm in Utah but yes there are many big hills here. The motor is laboring at WOT for long stretches. With my gearing and load the speeds are down around 35 - 40 mph so airflow is also down a little. I have the timing advanced quite far but not to the pinging threshold. I could retard it some but don't want to hold the engine back because the cooling system isn't doing it's job. The engine has been rebuilt but I did not get the information with it when I bought the truck so I don't know how far they bored the cylinders. I installed a significantly larger radiator out of my other '79 but I don't know how to tell if it is the 4 row super cool or not.

 

30 MPH should provide enough airflow to cool the motor.

You can move some of the fins aside enough to count the rows.

No, no spring on the old hose or the new one I purchased. Does this spring go inside or around the outside of the hose? Any idea on where to find one?

The spring goes inside the hose. It is important that the bottom hose has a spring, either built into the hose or inserted later. You shoud be able to get a hose with a spring at an Auto Supply store. You may also be able to get a spring there.

 

This is exactly what is happening. I couldn't quite get the thought to my fingers, but I've seen this many times on the race cars. They make restrictors for the thermostat housing, but this is unnecessary in this situation.