Thread: trying to cool down this 351m

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all right guys, now that I know what I have, let me tell you what's going on with this thing and get some input from you.

truck is 79' F150 custom but somebody put a bigger rear axle in it. long bed. runs great, pulls the boat great, but gets hot. I was driving it yesterday, 97 outside, and at lights or going slow on surface streets it got up to about 210 with and empty bed and no load. my uncle doesn't like this, wants it to run about 190 (like the 429 in the 51). he has changed the original radiator out some time back with a newer large radiator, but still top to bottom not cross flow. he is thinking either cross flow radiator or electric fans.

what are your guys thoughts on which route to go? I'm thinking if he replaced the radiator once we might try the electric fans, cheaper way to go.

Red

Are you using an engine driven clutch fan??? If so it might be failing... I would think if it were the radiator it would show up under load..

Red, need more info. Do you have a good shroud on the radiator? If so, is the fan inside this shroud and close to the radiator so it pulls a good amount of air across the core? I would guess from your statements you have a mechanical fan.....how many blades, and do you have a clutch on it?

As we have discussed in the past, heating up at lights is generally caused by insufficient airflow. Going down the road forces air across the radiator, but at lights you are depending on your mechanical or electric fan to do that for you. Even if you go to an electric fan you still need a good shroud otherwise the fan only pulls air across the section where the fan spins. With a shroud it pulls across the whole face of the radiator.

Lots of other factors, like timing (do you have vacuum advance on your distributor ?) Type and opening range of thermostat, etc.

Don

210* would be operating temp with a 195* thermostat.. the truck would have come with a 195* thermostat.. unless it gets to 230*, it's perfectly ok

With a 15 pound radiator cap an engine will get, depending on altitude, up to ~245/250*F before boiling. 210 should be no problem. It's a normal state of mind that people expect boiling at 212. If it's under a pressure device(cap), it can go much higher depending on the release pressure of that device. Just don't remove that device when it's hot as the water WILL boil at normal 14.7psi atmospheric pressure (and that 15psig cap is that much above the 14.7psia)

IIRC the boiling point raises 3* per PSI, so water will boil at 251* at 13 PSI with str8 water, mix 50/50 coolant and it goes 100* hotter... 210* is nothing

So how will it change with altitude,I have found my truck runs about 195.But after taking it down to Grass Valley (4000ft) and then driving up the hill again(7000)it went up to 210 for a little bit and then dropped again.Was wondering what altitude does to boiling point.Also what does distilled water do to boiling point as I run that with a water wetter.Thanks

I had fits trying to get the 350 in my 64 C10 to cool. Ultimately discovered the pulley hub on the water pump was slipping on the shaft. Stupid me, I thought the slight squeal was the alternator bearings.

BUT in the process: I now have an aluminum two-tube Summit radiator, an 18" electric fan, and 10" oil cooler. The fan is mounted in front of the radiator, and the cooler mounted below. Truck runs about 170 @ 90 degrees ambient on the road. Temp runs up as high as 190 at idle. I plan to put the fan on a thermal switch, and the oil cooler has a thermal bypass so it should do ok in winter.