351C Running Hot

The problem:
I live in Arizona and the temperature is ranging from 102-110 currently and if I drive at 50-60mph (C4 trans) in 100+ weather for longer than 10-15 miles the water temp will increase gradually until it hits 220-225 where I then pull off and travel slower until it cools down to about 205-210 again. Likewise if I maintain lower speeds around town it won't heat up past 210. In the morning, the weather is normally in the high 90's and I can travel 60mph for 30 miles and not really climb more than 112 degrees. If i stay at about 50-55mph in the morning I can stay 205-208. I believe these cars can handle the extreme heat as Arizona and Clevelands were both around and daily drivers in the early 70's.

Questions:
These are questions that I have been thinking about since I started my cooling off mission.

-How much does air temperature affect the water temp and cooling?
-What is the max water temp that I should feel safe driving my car in these conditions?
-I have a stock replacement 2 row radiator for my 68 that came with a 302, Did the 390's use the same radiator?
-Is it possible that the internal transmission cooler fluid is heating up at freeway speeds causing my water temp to rise that much?
-I don't have my heater plumbed. Would the lack of the extra fluid and circulation cause hotter temperatures?
-If the engine won't typically run hotter than 200 in 70-80 degree weather am I chasing my tail right now.

I want to explain exactly where I am at with my troubleshooting.

I don't know the age of my radiator however, I had my radiator cleaned/rodded/and tested 2 weeks ago. The inlet and outlet were on the same side so I had them switch that over which eliminated a long hose on the bottom and put the outlet on the same side as the water pump inlet. That all ran me about 75.00.

I have also replaced the conventional clutchless, shroudless, fan with a fully shrouded electric unit that really sucks some air. (shop rag test)

As of now I have put the correct 192 thermostat in. The retaining ring is present. I have a spring in the lower hose, and i back flushed the motor with a garden hose for a while just for good measure. I even ran a screen over the radiator inlet after the rodding to make sure no junk went right back in to it. (The screen is now off)

Motor condition:
Stock 351C 2V, stock manifold w/ Motorcraft rebuilt 2bbl carburetor. Hooker headers and Pertronix are the only upgrades at this time.
I just replaced all spark plugs and wires.
Oil is 10w40
91 octane gas
Compression just tested all cylinders range 150-160 warm.
Timing is set at 5 degrees initial @ 500rpm with 36deg total vacuum advance.
1 gallon of antifreeze and the rest is water.
Mildon 697-16335 Standard aluminum water pump.
Robert Shaw 333-192 Thermostat

I know this is a bit of reading but I want to throw my setup out there in case I have something wrong. My last option at this point is looking at having this thing re-cored with a 3 row but I don't want to do that unless I really have to as I am all out of $$Rancherobucks$$ ;O

 

Here is a picture of my radiator before I had the outlet switched and the core rodded out. It is a downflow with tanks on top and bottom.

After looking at the chart it is looking like my 2 row is just too small...

I appreciate the answers to all my questions. Thank you

 

@ Brandon ... I also think your radiator is undersized, particularly given the summer temps where you live.

But in the meantime, why are you only running 5 degrees of static timing advance? Should be more like 8 - 10 degrees static, and I'll also suggest that you should have the distributor vac advance connected directly to manifold vacuum. Only 5 degrees of advance will contribute to heating at low speeds.

In the general case, any radiator fan is an impediment to air flow above about 40mph or so. Looking at your pic, I'd remove that shroud and mount the fan some other way that leaves the core exposed.

Understand that the thermostat sets the =low= temperature in a warmed-up motor -- so if the one you have is a '190 degree' thermostat, then that is the lowest temp you should expect to see. Unless it sticks in closed position, the thermostat won't affect maximum temps [and noted here that you need to have the proper thermostat in a cleveland, which unlike most motors uses the thermostat to change the water flow path inside the motor when it opens.]

Is your motor boiling over? With a normal pressure cap [17 psi?] and anti-freeze coolant I'd guess it wouldn't boil until around 260F or even higher. Maybe you just have a bum temp gauge? You can stick an oven thermometer down into the coolant [through the open radiator cap] with it running in your driveway to get an idea how accurate your temp gauge really is.

 

5 degrees is where the motor sounded good and I read that 6 degrees was standard. I double checked Motor's Repair Manual and they say 6-8 for stock so I can try bumping that up a bit. What will change by connecting directly to the manifold?

The motor isn't boiling over and i have a 13lb cap on it. The temp gauge is new but I am not ruling out the fact that is is getting incorrect readings. I'm going to try the thermometer in the radiator and see what the results are.

 

5 degrees is where the motor sounded good and I read that 6 degrees was standard. I double checked Motor's Repair Manual and they say 6-8 for stock so I can try bumping that up a bit. What will change by connecting directly to the manifold? >brandon

+++++++++++++

What will change?

You didn't say how yours is connected currently, but in the usual case distributor vac is hooked to the 'spark port' on the carb -- which shows no vacuum at idle, but at larger throttle openings is manifold vacuum. Previous to the smog years, all cars had the distributor connected to manifold vac -- but retarding the timing at idle makes less NOx, so that was one of the first approaches.

The test would be: with the engine idling, if you disconnect the hose and it doesn't change rpm fairly dramatically, then you are connected to spark port. Without changing anything else, connect the distributor to manifold vacuum; you'll see the idle speed jump way up. If you put a timing light on it, you'll see it is showing maybe 30 - 35 degrees of advance.

The reason it speeded up is because you have optimized the timing for that [idling] condition. You can now adjust the idle stop to get the idle speed back to normal -- and all the extra fuel it was burning before was only going to create heat.

If setting it to 8btdc doesn't make it ping, and it still cranks OK when it is warm, then it'll run cooler and get better gas mileage at the higher advance. I'm guessing you'll hear from others here who run even more initial advance than that.

If it pings at 8, then back it up. If it is hard to crank when warm, then back it up. Otherwise, I'd keep advancing it until I ran into one of those two issues.

[just looked, my '71 manual says 6btdc for Cleveland]

 

Something else that causes an engine to run hot is your A/F mixture, too lean too hot. Ran across that tweaking my 351C on the test stand trying to find the right jetting, just a thought...

 

Cool that is good info. I am currently connected to a spark port on the carburetor. I am going to make some time tomorrow and change some of these things. I'll let you know how things go. I'm all about better gas mileage, I'm currently getting about 13.5mpg.

 

The main purpose of initial timing is for engine starting.
If you are a tuner, changes to initial timing can change low end horsepower, but for a street car your main concern is total timing and when it comes on.
With 36 of total timing you would need distributer alterations if you increase initial timing.
As to using port vacuum, you run the risk of creating a bog off idle with that change, and unless you spend a lot of time idling you won't see an MPG increase. When the port was changed, the distributer was changed, so you are back to distributer work if you want to do that.
To the cooling issue.
If it is not pinging, overheating, or losing power, you probably do not have a real problem. Check the gage, for sure.
That said, a better radiator can never hurt. With your vertical radiator, input and output placement make no difference. If you could change to a horizontal one they are more efficient, and more cores are always better.

 

With 36 of total timing you would need distributer alterations if you increase initial timing.
As to using port vacuum, you run the risk of creating a bog off idle with that change, and unless you spend a lot of time idling you won't see an MPG increase. When the port was changed, the distributer was changed, so you are back to distributer work if you want to do that. >ribald

+++++++++++

Uhmmm ... couple points: spark port vacuum IS manifold vacuum once the throttle plate is opened a bit. So the only condition where there is any possible difference between the two hookups is at very small throttle openings. Which amounts to a fair percentage of driving around town, waiting at lights, etc.

Brandon wrote '36 degrees total vacuum advance at 5000rpm' -- I think meaning he had the vac advance hose connected at the time. IOW, that's the total of centrifugal and vacuum advance, not high at all for a motor revving unloaded, and it might actually indicate a problem with one of the advance gizmos; I'd expect something north of 45 advance under that condition.

 

36 degrees was measured at 3000 rpm. It seems to level off at that range but could increase with more rpm for all i know however, I haven't tried it as my valve springs don't seem to be in the best shape and I haven't been pushing it. My vacuum advance unit is adjustable so I can tune it easily. 36 was a number I found to be common on the web since I don't know how to read the Motor's manual specs.

My 2100 has 1.08 stamped on the side. I never really thought it would be too lean or how to figure it as well?

What carburetor were you running on the bench and what did you switch to?

 

When I got my wideband sensor to further tweak the carb... http://www.plxdevices.com/wideband.html
I found out just what a incorrect setting will do, you would be surprised...

edit: timing has nothing to do with your overheating issue, look else where...

 

These numbers don't care about vacuum advance connected or not. You can't exceed the mechanical limit by either centrifugal or vacuum advance. >72gtva

++++++++++++++++

Ahhh ... I don't know any gentle way to put this. Let's compare notes.

Both centrifugal and vacuum advance mechanisms have travel limit stops, true. But they are not interconnected at all, they are completely independent. And the advances they create =add= on top of each other

Centrifugal advances by twisting the points-cam and rotor ahead [further ccw] of the main shaft with increasing rpms, and the vac advance works by rotating the plate on which the points are mounted clockwise, essentially moving the goal posts forward. The one mechanism knows absolutely nothing about the state of the other.

So if he measured his max degrees with the vac advance connected [and I think that's what he reported] then he'd get your ~40 degrees of mechanical PLUS what the vac advance was adding -- which would be at full extension on that car with no load on the motor at 5k rpm.

This is easy to test, if you have doubts; with the motor idling, use a hand pump to force the vacuum advance, observe with your timing light that it indeed advances timing. Then with that holding at maximum, use the throttle to increase revs, and watch it advance some more due to the centrifugal mechanism. The total advance is static plus centrifugal plus vacuum.

Edit: @ Brandon -- when you see web specs about total advance, they are speaking of centrifugal advance, not the combination of centrifugal and vacuum. That screw in the vac advance spout is intended to limit the amount that the vac unit adds, not to adjust the total advance.

Suggest that you spend a little more time with the timing light, check how much the distributor advances with no vacuum hose attached, due to the centrifugal mechanism alone; that should be around 30 degrees at 3k rpm and above. Then with the motor idling, connect a hand pump [or just manifold vacuum] to the can to see how much the vac advance unit adds by itself -- that's what that screw is meant to fiddle. Should add 10 - 15 degrees. Of course, when it matters to have a 36-degree limit is when you have the throttles wide open, pulling hard -- at which condition there will be no manifold vacuum and the vac advance unit thus removes itself, i.e., retreats to relaxed position.

 

You ar correct. That is why you get a lean bog off idle using your method.

 

Just a couple of quick comments about how your system is set up Brandon.
There were different radiator packages available for a given drive train depending on which part of the country a vehicle was going to be delivered to. I'd expect most 60s-70s-80s Fords delivered in Arizona to have at minimum a 3 row radiator and for any of the big block cars or ones set up for towing usually ran a 4 row.
I had a 2 row standard small block radiator in my 67 with a 4-V Cleveland and it didn't cool well at all. That's here in Washington where we hardly ever see days above 90 degrees.
I now have a big block radiator that was re-cored with a 3 core truck super-cooler core and run a 185 degree thermostat. In anything less than 100 degree weather I can't get it to run hotter than 190.

Get a big block radiator for your Chero. it will solve your problem.

In the mean time as RancheroBuck$$$$ are scarce, try putting a 160 or 185 degree thermostat into your ride. The 192 degree 'stat you're running is restricting the coolant flow until the coolant temp gets above 192. that's great if you drive in winter in the Great White North where you need every bit of heat your engine can generate just to run the defrosters, but not so critical in Arizona. 'Specially not if you've got the heater disconnected...
Last comment is just to echo what Carl said about the shroud restricting air flow at higher speeds. Vents in the shroud on all four corners with rubber flaps to close at low speeds should make a noticeable difference.

Hope this helps!!!

 

351C were designed to run at 192, there are no plus or minus on a Cleveland...