1979 F350 4x4

[Teacher John]

This may be too new a truck to discuss. I have a '79 F350 4x4 that originally had a 400M and C6. I removed the 400M and replaced it with a 460 bored 60 over with 68 460 heads, 270 4x4 Comp cam. I have a 4 core aluminum radiator with the biggest electrical fans available, oil cooler, and trans cooler. When the 400M was installed, it ran about 180, but now during the summer, it'll creep up to 225. Any ideas to keep this ol' girl running cooler?

[KULTULZ]

...with the biggest electrical fans available, oil cooler, and trans cooler

Two fans I assume? One for AC? Are they pull or push style? If pull, full shrouding? Where are the oil coolers mounted?


Guess I should also ask if it overheats @ idle, slow traffic and/or highway.

[Teacher John]

Originally Posted by KULTULZ

Two fans I assume? One for AC? Are they pull or push style? If pull, full shrouding? Where are the oil coolers mounted?


Guess I should also ask if it overheats @ idle, slow traffic and/or highway.

Two big shrouded fans that pull air through. The other coolers are mounted in front of the radiator. I removed all of the AC BS.
It will overheat if it idles once it is driven, but will begin to overheat rollin' down the road at 65.

[rotorwrench]

You might want to do a pressure test or maybe even an exhaust gas test just in case there is a leak somewhere. I know that 460s can be bored that far and generally with no problems but if there is a leak or even a cracked head, there will be constant problems.

[KULTULZ]

Originally Posted by Teacher John

Two big shrouded fans that pull air through. The other coolers are mounted in front of the radiator. I removed all of the AC BS.

It will overheat if it idles once it is driven, but will begin to overheat rollin' down the road at 65.

Can you post a photo(s) of the fan install? Do the oil cooler heat ex-changer's block a large amount of air-flow? If you put a tissue on the front of the radiator, will air-flow keep it captured?

It sounds like poor air-flow or a weak WP. Thermostat good and of quality? Possible collapsing lower hose? All air out of the system? Coolant recovery system?

Like mentioned, perform a pressure test. Does it lose coolant?

[turnpikecrusier]

Sponsored Links (Register now to hide all advertisements)

Check your vacuum advance on the distributor. I had similar problem with my 460, advance wasn't working. I installed new one problem solved.

[Teacher John]

Originally Posted by turnpikecrusier

Check your vacuum advance on the distributor. I had similar problem with my 460, advance wasn't working. I installed new one problem solved.

I'll check the vacuum advance. I may have disconnected it. My brother said it was NOT necessary and robbed me of performance. Hmmmmm

[Teacher John]

Originally Posted by KULTULZ

Can you post a photo(s) of the fan install? Do the oil cooler heat ex-changer's block a large amount of air-flow? If you put a tissue on the front of the radiator, will air-flow keep it captured?

It sounds like poor air-flow or a weak WP. Thermostat good and of quality? Possible collapsing lower hose? All air out of the system? Coolant recovery system?

Like mentioned, perform a pressure test. Does it lose coolant?

I'll post a pic soon. It draws a ton of air through the radiator. The shroud completely covers rear of radiator up to fans. Thermostat is good and the lower hose is not collapsing. I shoved a thick piece of PVC in there to prevent that. I could not find a lower hose that would fit that had a spring. Thinking back, I had to use aftermarket pulleys in places. One was smaller than the original.

[Teacher John]

Originally Posted by rotorwrench

You might want to do a pressure test or maybe even an exhaust gas test just in case there is a leak somewhere. I know that 460s can be bored that far and generally with no problems but if there is a leak or even a cracked head, there will be constant problems.

We tested the heads and block. There were no leaks. It is not using coolant and does not smoke as if water was entering the system.

[Teacher John]

Crankshaft pulley is smaller than the original. Installed a nice high-flow waterpump.

[KULTULZ]

Originally Posted by turnpikecrusier

Check your vacuum advance on the distributor. I had similar problem with my 460, advance wasn't working. I installed new one problem solved.

Originally Posted by Teacher John

I'll check the vacuum advance. I may have disconnected it. My brother said it was NOT necessary and robbed me of performance. Hmmmmm

The man makes a good point and yes it is needed unless the DIST has been re-curved to use centrifugal advance only.

[Teacher John]

Originally Posted by KULTULZ

The man makes a good point and yes it is needed unless the DIST has been re-curved to use centrifugal advance only.

It's an MSD distributor. I have no idea if it's been re-curved.

[scicala]

Originally Posted by Teacher John

I'll check the vacuum advance. I may have disconnected it. My brother said it was NOT necessary and robbed me of performance. Hmmmmm

A vacuum advance does not rob you of any power. When I worked in the 80's at Roush, we were dyno'ing some 460 Ford engines and more than one person noticed the exhaust temps were higher than other engines. The vacuum advance will allow more spark advance when cruising (light to moderate loads) which in turn lowers exhaust temps considerably.


Sal

[Teacher John]

Originally Posted by scicala

A vacuum advance does not rob you of any power. When I worked in the 80's at Roush, we were dyno'ing some 460 Ford engines and more than one person noticed the exhaust temps were higher than other engines. The vacuum advance will allow more spark advance when cruising (light to moderate loads) which in turn lowers exhaust temps considerably.


Sal

Well, it turns out the vacuum advance is connected. What should the timing be set at in your opinion?

[robib]

If the crankshaft pulley is smaller than the original, as you stated, and the water pump pulley is stock (to a 460), then the pump is turning slower than it should. Find out what the diameters should be and replace that which is not correct. Start there.



Electric fans are fine as long as they are really pulling the CFM they claim and match what is needed by your application. Make sure the power wires are big enough to provide the proper power. Also, solid shrouds (obviously not where the fans are) can actually inhibit the flow of air as you are driving. Some shrouds have holes cut in them with rubber flaps that open as you drive. 460 engines were available stock in 79 Ford pickups. They used water pump driven fans and had no problems.

[scicala]

Originally Posted by Teacher John

Well, it turns out the vacuum advance is connected. What should the timing be set at in your opinion?

On a stock 460, the base ignition timing is from 6 to 10 degrees depending on the year. This at about 600 RPM idle with the vacuum advance disconnected.
To check total centrifugal advance timing, leave the vacuum advance disconnected and with the trans in park or neutral open the throttle and see at what RPM the advance stops increasing. Ideal would be from 30 to 35 degrees total by 2500 to 3000 RPM. To change the speed you reach total advance, you would need to change the advance springs in the distributor.
I'm sure your probably good to go with the distributor you have.


Sal

[finn1]

Ditch the electric fans and find a mechanical fan from a big block Ford truck engine.

Electric fans are fine for an econobox, but the small electric motors they employ aren’t adequate to deliver the power required tp push enough air to cool a big block engine.

Take a look at the fans in a newer F350 and compare them to what you have now.