Driving without the hood – engine temps and other thoughts

[NiceGuyEddie]

150449

I have not driven the car in the summer for nearly a decade because during stop & go the engine temps make me nervous. I took the hood off to drive around for the holiday weekend, and to my surprise I didn’t notice any difference.

For those who have not known me and/or followed my experiences since 2005, my first motor was a 306. I now have a 347 and I re-used all the accessories, even the 570 carburetor. The water runs at 185 and the oil runs about 140. When you hit stop and go traffic, the oil QUICKLY gets up to 185, then the water and oil follow each other and creep up -200, 220 - sometimes even a little higher and I get nervous. This never happened with the old 306 which was about 300hp.

Once again, I was surprised that having that engine breathe seemed to make no difference. I heard that hood louvers help a lot, and I have a friend with an older carbureted jeep and he said that when he added hood vents he can literally see the heat coming out of the hood.

Couple of thoughts:

I have underdrive pulleys. The crankshaft pulley is smaller than (stock 5.0) and the waterpump pulley is larger than stock. The belt is then 5” shorter, but overall the waterpump is turning slower. But it’s weird that the OIL that creeps up while at first the water remains the same. And when you get moving on the freeway, the temps go back down very, very fast.

Even though I have a PowerMaster alternator and the voltmeter is pinned at 15, at idle my headlights & dash lights dim a little bit. Recently I noticed that footbox blower “dims” a little bit at idle, so I wonder if my fan is also going a little slower. Judging by the sound of the foot box blower by ear, my guess is 20% slower at idle.

There was a time I considered adding pusher fans, but if the temps are the same with no hood I’m not so sure they would help.

[Al_C]

Eddie, I think this makes sense. In my non-engineering mind, I believe the oil is taking up the slack of the coolant. Your water pump is not turning as fast, so less coolant is circulating. Nevertheless, the oil is circulating quite nicely, so it takes up the heat that the coolant can't (because it isn't moving quickly enough). The engine is seeking equilibrium and the oil gets the nod. I bet your oil temp will be better if you get a different set of pulleys on your crank and water pump.

[NiceGuyEddie]

I could have also mentioned I have the Levy oil pan and 8.5 quarts of oil. It makes sense that the oil is taking up the heat. On very cold days on the freeway, the water is 185 but the oil is only about 120. Now the oil is scary low temp. Stop & go in the winter has the same result except the temps don't get super-high.

The oil temperature sensor is on the oil pan and I guess it's very sensitive to register the changes in heat.

The 347 is about 450hp, the 306 was about 300hp - the 347 is 50% more power (and likely heat) but in stop and go at low rpm's the hp output of each engine doesn't differ as much.

[Railroad]

Change your pullies to stock ratios and add a bottle of Water Wetter or Purple Ice to the cooling system.

[NiceGuyEddie]

Fortunately, I still have my stock pulleys and even the old belt - it shouldn't be so dry that I can't use it for a short while.

I'm just surprised that this motor would do this, the 306 was always perfectly fine - even during hard autocrossing and waiting in grid at idle for as much as 8-10 minutes. I was a younger lad back then - I even trekked it to Bob's Big Boy one summer Friday afternoon thru traffic when it was 100º outside. (Engine temps were fine, I was not :p )

I've never heard of Water Wetter or Purple Ice. I'm sure it certainly couldn't hurt. The instructions of each say 1oz/quart of coolant - anybody remember how many quarts of coolant for a 347, AFCO/FFR radiator and FFR heater? :confused: :confused: :confused:

[NAZ]

As others have said, not enough water flow at low RPM.

Your 347 has a rather short rod ratio which can add friction which creates heat. And depending on the ring package, even more friction & heat. The rings can contribute as much as 40% to the total friction the engine has to overcome. So even while you might expect there wouldn't be much difference in heat generated between the two engines at idle, there could be if the 347 is creating more friction. And to overcome additional friction requires burning more fuel which just adds to the heat load.

[Jeff Kleiner]

Get rid of the under drive pulleys before I have to repeat my “don’t try to use race car parts on a street car” sermon for the hundredth time. And then put the hood back on ;)

Jeff

[NiceGuyEddie]

I understand the above if the rod ratio is referring to the longer stroke. I never considered that even at idle or low RPMs "more fuel = more heat". Makes sense.

I don't know the rings I have, but the engine was built as a race motor and it uses 20W-50 Valvoline with zinc additive. I have a Mellings high-volume oil pump. I wonder if the oil itself contributes. The old engine used 10W-30 or maybe 10W-40.

[rich grsc]

Removing the hood isn't going to make the engine cooler. :rolleyes: The coolant and radiator do that, along with the oil. Temperature goes up at an idle, no surprise you have an under drive belt setup. Your lights dim at idle, no surprise you have an under drive setup, and a one wire alternator. Under drive belt setups are on of the most ridicules things you can put on a car. They almost always cause problems that FAR out way any supposedly increase of power.
HIGH volume pump, sucks up extra power, causes heat in the oil by circulating more oil than is needed, same as the extra heavy weight oil.

[NiceGuyEddie]

Get rid of the under drive pulleys before I have to repeat my “don’t try to use race car parts on a street car” sermon for the hundredth time. And then put the hood back on ;)

Jeff

The underdrive pulleys made a kick-in-the-pants difference when I started with a mild 260hp 5.0 with iron heads. They may not matter as much anymore. Now that we are on the subject, any idea how much they allegedly add?

[NiceGuyEddie]

Hi Rich: I guess it doesn't matter THAT much in this discussion but I only used the underdrive pulleys for the crank and waterpump. I didn't use the power steering pulley or the alternator pulley.

I'd like to take out my old pulleys and see what the ratios are and how much slower my waterpump is spinning.

[rich grsc]

Hi Rich: I guess it doesn't matter THAT much in this discussion but I only used the underdrive pulleys for the crank and waterpump. I didn't use the power steering pulley or the alternator pulley.

I'd like to take out my old pulleys and see what the ratios are and how much slower my waterpump is spinning.
Pulley on the crank, slows everything that the belt runs

[NiceGuyEddie]

If I have time, I'll geek out on this - the current belt is about 5" shorter, which might be +10% more RPMs after the reduction between crank and waterpump.

Well the good news is the hood is off so the engine bay is easier to work on....

[Cobradavid]

Agree with others about the underdrive pulley set-up.

Is your radiator fan coming on as it should?

In stop-and-go you have almost no ram air flowing though the radiator (regardless of hood or no hood), so the rad fan needs to be working correctly.

[Al_C]

Please let us know how the temps change once the pulleys are changed! ;)

[Railroad]

Do the pulleys and water wetter separate and record the results. I think you will be pleased.

[mike223]

No dispute that under driving the water pump isn't helping.

But losing airflow around the oil pan is why you notice the oil temp creeping up first.

[Rdone585]

Double ditto on the radiator fan coming on when at idle and making sure the water pump and all accessories are turning at the proper speed. As NAZ said you have to have enough water flowing for it to be cooled efficiently. You might also share what type of cooling setup you have - radiator size and number of cores, CFM of fan(s), shroud or not, thermostat open temp or just restrictor plate.

[NiceGuyEddie]

OK GUYS

This is going to be fun. I haven't chased down a gremlin in a long, long, time - that's a good thing but I look forward to my results.

The car is stored at a house that's inland and it just got REAL hot out. It's gonna' be a while before the garage temps get down to reasonable levels to do even a small amount of work, but I will definitely try the water wetter first and go for a quick drive at night. I'm a wee low on coolant so it looks like I can add the whole thing to the overflow. It says 1oz per quart of coolant - anybody remember about how many quarts of coolant go into a 5.0 block and the FFR radiator & heater?

To re-summarize, my setup is FFR AFCO radiator, Fox Water Pump, FFR electric fan, Breeze radiator shroud, Breeze top radiator close-off, and the fan is on a manual switch.

[Rdone585]

I would add a temperature sensor to automatically turn on the fan when the engine coolant reaches 190, or is it 195. Use the switch to override the sensor and force the fan on whenever you want.

[AC Bill]

anybody remember about how many quarts of coolant go into a 5.0 block and the FFR radiator & heater?

Not sure about the Afco rad, but the system on a stock Mustang 5.0 is 14 quarts when bone dry.

[hineas]

We have the BluePrint 347 with the stock radiator and a heater. If memory serves, we used roughly 3.5 gallons when we filled it last month.

I use the Purple Ice in my 2000 Jeep Cherokee because the cooling system isn't great. The improvement in cooling is noticeable, but not huge. I'm intrigued to see if it makes a difference for you or if you will need to change the pulleys.

[Railroad]

The coolant additive will not do anything in the overflow tank, unless and when the system pulls it into the engine.

[CraigS]

My thoughts;
- put the stock pulleys back on everything.
- use that manual switch as soon as the temp comes to 180. I find it much easier to prevent the temp from rising than to bring it back down.
- tell us what you have for an overflow tank and how it is plumbed. You have been around for a long time so I kind of assume you have a proper tank, T-stat etc but we all know what assuming does. Pics would be great.

[totem]

Back to the OP.

Coolant temperature between 200-220f is not that high. Depending on thermostat, it starts opening at 180/195 and is full open at 200/215. Only then you may have problem.

Also, in a cooling system pressured with a 15psi radiator cap, pure water boils at 250F. Add coolant and you’re far from boiling. I’ve overheated an engine to 280F without damage.


Don’t worry about oil temperature. Under significant load, oil runs about 20F hotter than coolant. Oil has to be hotter than coolant for a liquid-liquid oil cooler to work. Oil temperature is not regulated otherwise. You won’t run into oil temperature issue unless racing.

You have not driven the car in the summer for nearly a decade because you’re nervous? It’s time to do something.

I agree that you should remove the underdrive pulley and add an automatic fan switch. It will lessens worries.

[NiceGuyEddie]

150449

My overflow is plumbed with a clear tube to the bottom of the octagonal tank. The clear tube acts as a level indicator. The tube came off a $14 Autozone overflow tank and the markings used to say PFA. The top of the octagonal tank has a vent normally used on rear axle. I plan to replace the clear tube - it's been a while.

RICH - can you please help me? What does a 1-wire alternator have to do with the lights dimming at idle? Years ago, I don't recall any other choice, and that Powermaster Alternator is a whopper. My volt meter is always pinned at 15V. It doesn't move when revving the engine or at idle. I wonder if the meter is even wired properly?

[rich grsc]

150449

My overflow is plumbed with a clear tube to the bottom of the octagonal tank. The clear tube acts as a level indicator. The tube came off a $14 Autozone overflow tank and the markings used to say PFA. The top of the octagonal tank has a vent normally used on rear axle. I plan to replace the clear tube - it's been a while.

RICH - can you please help me? What does a 1-wire alternator have to do with the lights dimming at idle? Years ago, I don't recall any other choice, and that Powermaster Alternator is a whopper. My volt meter is always pinned at 15V. It doesn't move when revving the engine or at idle. I wonder if the meter is even wired properly?
One wire alternators don't do a good job of charging when at low rpm's, they require a higher rpm than do other alternators, such as a 3G. You have made that somewhat worse with the under drive pulleys. Your volt meter should be in the range of 13.8 to 14.5 volts, and should change when you turn on or off the headlights.
I have never liked 1 wire alternators, they're for tractors. I have a small case 3G, that costs about $50, never had a moments issue.

[CraigS]

I ran a 1 wire for 15 years w/o problem. Once in a while I would ease out of the garage trying to keep quiet as I could and would notice 1/2 block away the the alt was not charging. A quick blip to 2000 and it started charging. Your larger pulleys will help w/ this was well as the coolant temp.

[johnnybgoode]

150449

I have not driven the car in the summer for nearly a decade because during stop & go the engine temps make me nervous. I took the hood off to drive around for the holiday weekend, and to my surprise I didn’t notice any difference.

For those who have not known me and/or followed my experiences since 2005, my first motor was a 306. I now have a 347 and I re-used all the accessories, even the 570 carburetor. The water runs at 185 and the oil runs about 140. When you hit stop and go traffic, the oil QUICKLY gets up to 185, then the water and oil follow each other and creep up -200, 220 - sometimes even a little higher and I get nervous. This never happened with the old 306 which was about 300hp.

Once again, I was surprised that having that engine breathe seemed to make no difference. I heard that hood louvers help a lot, and I have a friend with an older carbureted jeep and he said that when he added hood vents he can literally see the heat coming out of the hood.

Couple of thoughts:

I have underdrive pulleys. The crankshaft pulley is smaller than (stock 5.0) and the waterpump pulley is larger than stock. The belt is then 5” shorter, but overall the waterpump is turning slower. But it’s weird that the OIL that creeps up while at first the water remains the same. And when you get moving on the freeway, the temps go back down very, very fast.

Even though I have a PowerMaster alternator and the voltmeter is pinned at 15, at idle my headlights & dash lights dim a little bit. Recently I noticed that footbox blower “dims” a little bit at idle, so I wonder if my fan is also going a little slower. Judging by the sound of the foot box blower by ear, my guess is 20% slower at idle.

There was a time I considered adding pusher fans, but if the temps are the same with no hood I’m not so sure they would help.

Hey Eddie. Another idea for you. I've been running one of these FlowKooler water pumps for a couple of years now and my motor (414W) never gets over 190*. They have a very nice billet impeller that is designed to maximize flow at lower engine speeds. It's a bit of a pain swapping out pumps but just thought I would pass along the info. Good Luck. Scott

https://flowkoolerwaterpumps.com/collections/hi-flow-water-pumps/products/1660-1979-1993-ford-lincoln-mercury-302-water-pump

150845

[Avalanche325]

I am not a fan of 1 wire alternators either. Yeah they basically work, but as stated they are for tractors that run at a constant RPM hours at a time. They don't start charging until RPMS come up and can drop out when RPMs drop back down.

I have a 500 hp 347 with CFR underdrive pulleys and live in Florida. I never have an overheating problem in traffic, or on the track. Maybe your underdrive pulleys are on the extreme end of the equation. As everyone says start there. You should be able to enjoy your car in the summer.

Other things are:
1. Do you have the correct rotation water pump?
2. Are your head gaskets on backwards? The cooling passages get bigger as you move to the rear.
3. No need to run a high volume oil pump on a SBF. No real issue heat-wise.

[NiceGuyEddie]

Small update:

I dug out my stock pulleys and I remembered that I never changed the pulley for the alternator. The one that came with the underdrive pulley kit is smaller, this must be part of the reason for the dim lights and footbox fans at the stoplight. (I didn't change the pulley because I didn't own an impact driver at the time.)

I added Royal Purple Purple Ice. It was a good timing because I was down about a quart of water anyway. So far I've had two long, cool drives on the freeway. The water used to run 185º when cruising on the freeway with no electric fan. The last two trips it ran at 175°. Interesting stuff. I have not had a chance to get stuck in any stop-n-go traffic yet.

[NiceGuyEddie]

160136160137160138

I finally had time to get back to this and I've re-installed the stock pulleys. It's been so long, I've forgotten there is more than one way to route the belt.

I went for a short drive last night and it was too cold to see about any hot temps in stop-n-go but the good news is as expected, the lights aren't nearly as dim at idle with the stock pulleys. (They are dim a little, little bit compared to say even 1,000 rpm.)

The tensioning rod is at its maximum with this setup (picture 3) so I'll see if I can do it like the second photo. I have four belts in the garage to play with.

[StoneyCreekCobra]

johnnybgoode, would love to come see your beast, Im just outside Hamilton in Stoney Creek
John

[johnnybgoode]

Hey John.

I'm in Ottawa. If you are going to be out this way let me know and we can set up a time for sure.

Take care. Scott

[zee]

johnnybgoode, would love to come see your beast, Im just outside Hamilton in Stoney Creek
John

Small world, I am in Milton. I ride my motorcycle around you very frequently (not in winter obviously)

[StoneyCreekCobra]

there are many lovely backroads around here to take a Sunday ride/drive on, have a MGB GT right now but looking for something a little more noisy LOL
John

[NiceGuyEddie]

SMALL UPDATE:

I took the car out yesterday and although it was a warm January day in LaLa Land, it likely wasn't warm enough to see about the engine getting really hot in stop-n-go.

The good news is I didn't seem to tell a difference in the power of the engine with the stock pulleys put back on. Back when I had a mild 306, about 270hp - YES, I did tell the difference when installing the underdrive pulleys.

[NiceGuyEddie]

UPDATE:

I finally was able to gather two willing mates to help me put the hood back on. It was near 90º in LaLa Land and I drove as hard as I could. Water and oil got up to 210º during stop-n-go but nothing was too hot that it made me nervous. Temperatures went back down to 185° after 5-10 minutes on the freeway. All signs point to it being a good decision to take the underdrive pulleys off.

Dumb question: The engine seems to run a little smoother. Is it possible that since the alternator is spinning a little faster, I'm getting a little better spark? The reason I ask is I have a lightweight flywheel and the rpm's drop instantly when shifting unless you feather the throttle. During shifts, the engine seems happier and I wonder if it has anything to do with a better spark. The voltmeter is always just over 12V and it moves a little bit depending on rpm but otherwise it does not move enough for me to tell the difference.