[ponyakr]

Originally Posted by Sirrotica

For the people that choose to ignore physics there are restrictor washers. As long as the radiator has plenty of airflow and area, you cannot pump water too fast through a cooling system.

If you don't have enough radiator area or airflow through it, your fighting a losing battle from the beginning. Restrictor washers won't fix it either. Restrictor washers will raise the pressure of the coolant on the high pressure side of the pump possibly reducing cavitation from a poor impeller design, a band aid for another problem which should be addressed and repaired.

You seem to have had quite a bit of circle track experience. Smokey had quite a bit also. His opinion differs from yours. As I said, opinions differ, on this subject, and have for a long time.

[tom s]

When Smokey was doing pontiacs they used a 4 bolt water pump and there was nothing do adjust about water pumps.Not a good person or era to compare to.Tom

[Sirrotica]

Originally Posted by ponyakr

You seem to have had quite a bit of circle track experience. Smokey had quite a bit also. His opinion differs from yours. As I said, opinions differ, on this subject, and have for a long time.

The difference is, I have cited articles that support my position written by people and manufacturers that have lots of engineering and practical experience.

I cited the OH prone 6.5 turbo diesel and the engineering changes that GM made to the cooling system to stop the engines from overheating and cracking the cylinder heads. Every modification made was to enhance the speed at which the coolant circulated through the cooling system. After GM made the enhancements the cooling problems went away and the 6.5 turbo diesel was used in all of the Humvees all over the world in combat situations, many times in the desert in the middle east.

I have lots of Pontiac cooling system trouble shooting experience with Pontiacs running hot in some of the worst case scenarios. Never once have I fixed an OH problem by putting restrictors in the thermostat housing, street or in a race car. And never have I thrown up my hands and not fixed the problem. Sometimes there are multiple problems and each must be identified and repaired, it's not always just one thing that fixes the problem.

As has already been mentioned if slowing down coolant would stop overheating, why is it OEM companies never do it? Each time the manufacturers make improvements to the air flow and the coolant flow. Heavy duty cooling systems don't come with smaller waterpump impellers and slower water pump pulleys, or restrictors in the cooling system.

If I was to heat up a piece of steel and cool it with a hose would a slow trickle of water or a wide open hose cool it faster? Same principle, I think we know which scenario would cool the steel quicker with a constant water temperature the large stream would get the job done quicker.

Question to the OP: where is your temperature gauge installed on your engine, cylinder head or water crossover?

[ponyakr]

I've read that you can't believe anything you read on the internet.

I've read LOTS of posts by guys saying that using the correct size restrictor, actually did make their engine run cooler. But, I suppose each & every one of these guys was just lying about it.

Hey, I've never done any testing, so I don't have a vote. Ya'll can believe whatever you like. I won't agitate anybody with another post on this thread. Ya'll have at it.

[Sirrotica]

Originally Posted by ponyakr

I've read that you can't believe anything you read on the internet.

I've read LOTS of posts by guys saying that using the correct size restrictor, actually did make their engine run cooler. But, I suppose each & every one of these guys was just lying about it.

Hey, I've never done any testing, so I don't have a vote. Ya'll can believe whatever you like. I won't agitate anybody with another post on this thread. Ya'll have at it.

And in all of the restrictor stories you reviewed, is there anyone at all that said the restrictors didn't work? If there was no negative stories then I must be full of crap and all the OH problems I ran into over the years could have been fixed by just putting a washer in the thermostat housing...........

[Speargun]

Guys, I appreciate the help & suggestions everyone has been giving, but please take the thermodynamics & hydrodynamic disputes to another thread or pm's.
Thanks,
-Jeff

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[Speargun]

Both sensors are in the crossover about an inch apart to the passenger side of the t-stat housing.

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[Sirrotica]

Originally Posted by Speargun

Both sensors are in the crossover about an inch apart to the passenger side of the t-stat housing.

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Just checking, as the head location will run about 15-20 degrees hotter than the crossover will.

[Goatracer1]

You seemed to have checked everything in the cooling system. Time to check the engine itself. Check your timing and make sure you have enough advance. Also make sure it's not running too lean. If you are having detonation problems and are retarding the timing to get rid of it that could be your problem. The engine could still be detonating even though you can't hear it. If your compression is too high enrichening the mixture may help. If the engine had been detonating in the past you may now have head gasket problems. If you don't have the equipment to make these checks have someone you trust do it for you before spending anymore money on cooling system changes.

[tom s]

I drove my 69 bird today with a factory 350 auto radiator.I have a 160 thermostat.I show about 154 on the housing.I get about a 25 -30 degree drop from the bottom to the top outlets.Factory shroud and factory flex fan.Engine is a 455 bore 3.375 stroke engine.I can let it idle in the driveway in a 80 degree day and wont get over 160.Also 160 on the freeway at 70 MPH at 2000.11 bolt water pump.FWIW,Tom

[Speargun]

So I got my hands on a couple of Spal "Extreme Performance" 11" fans and put them in last night. They are rated at 1605 cfm & pull a max of 35 amps vs. the medium profile fans that were on the car rated at 932 cfm & 12 amps.

I drove into town this morning (65*-70*) and the temps stayed @ 190* or below.
On the way home (85*-90* with a high of 94* expected later today, gotta love Florida weather) in some town traffic and about 10 miles of open road at the end, total of about 25-30 miles, the temps got as high as 206*.
I checked the temp drop with a laser when I got home & got the following:
Upper hose - 175*
Lower hose - 165*
Electric sender in x-over (brass) - 203* which matched what the FiTech said the temp was.
Mechanical sender in X-over (Alum) - 190* Gauge read 194*ish.
Taking a reading off of the filter, it was either reading the glass of the metal from for the screen inside, was 190*ish.
I think the brass in the electric sender adapter fitting isn't shedding heat quit as fast as the aluminum adapter for the mechanical sender and may be part of the reason it reads around 10* higher and doesn't respond as quick as the AutoMeter.

Nearly doubling my cfm definitely made a difference, but it may not be enough for summertime driving, especially once I get the A/C working.
Time to start looking for a factory shroud & clutch fan I suppose...

[Speargun]

A question for the radiator experts:

Which cools better?
4 row brass
4 row aluminum
2 row (1" tubes) tri-flow

[68 Firebird]

Have to say you may benefit from an AC style configurations for your cooling system.
Mine is a 8" CP 6.25" WP pulley to speed up pump. Stock 180 stat and aluminum rad with 2 rows that are 1". All panels upper and lower in place along with mastic area seals.
7 blade AC fan with Hayden severe duty fan clutch.
I run very close to stat around town and maybe 188-190 on highway runs.

[Ccass]

Originally Posted by Speargun

A question for the radiator experts:

Which cools better?
4 row brass
4 row aluminum
2 row (1" tubes) tri-flow

In this order as a general rule.....

2 1" row aluminum - Whether tri-flow is better or not depends on multiple things. We have both. You want to do a test for us? If yes, PM me and I'll give you the details.
4 row aluminum is 2nd best
4 row brass is next
3 row aluminum
2 5/8" row aluminum
3 row brass

there should not be too much debate here.. All the top aluminum radiator companies use 2 large rows for a reason.

[Squidward]

I also run a 6"-ish wp pulley to go with previously mentioned shroud/fan/clutch/4 core aluminum rad setup. Fan is inset into the shroud somewhere between 1/2 and 3/4 IIRC. I run a mech gauge out of the water crossover. My heads don't have a bung.

After putting in the 4 core/clutch/shroud setup (still running 69 short nose 11 bolt pump) I left the tstat out to test cooling ability without it. In the winter the temp gauge took a long time to get into the 110-120 range. I was spending the spring/fall months not getting over 150 during any condition. I went with a 180 tstat, and it hasn't seen the high side of the tstat setting except for once: My last trip to the strip had me going through the traps above 5k, and my wp divider plate (was clearanced to a tight spec) somehow ended up sucking into the impeller, and my pump blew out a gasket. I actually UN-clearanced my plate some when I did the repair in the pits, and it still cools great.

I wanted electric fans. I really did. I loved the clearance near the radiator, and I loved not having a whirring sausage slicing deathtrap under the hood. But I wondered why my friend Mike could run his 11 second 455 68 'bird all day long on a factory brass 4 core, and I couldn't come close. I decided to just copy his setup of shroud/fan/clutch, and problem was solved.

Along the way I did flirt with the 1st gen chin spoiler. I started fabricating my own, but then I solved my issues. Also, I installed the air filler plates between the nose and the radiator support. Those probably help some, but I know people without the fillers who don't have cooling issues. All I can say is that I underestimated the air flow need.

[salesguy01]

I also have the dual spal fan setup, alum heads, be cool radiator, flowkooler pump, 180 thermostat. Here is south Louisiana it gets very hot. The dual spals are adequate and will keep it at 180, on the highway the fans don't need to come on as it stays at thermostat temp...... However those derale 4000 cfm fans are looking attractive as I think the 11" spals I have are borderline


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[1967Tempest]

Originally Posted by Speargun

I have a 2 speed " Mark VIII" fan, but it won't fit without hitting my water pump pulley.

I currently have the timing set just below where I get spark knock.

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I have this fan in back of a Griffin 2 row 1.25" cooling finned radiator. The new 468 runs 190*-195* all day in northern VA traffic. (Driving it to NC from NJ) The lanes were very freshly paved so the road was BLACK!!! Imagine my surprise that an early March day got over 90*!!

I use the Hollister Road relay assembly with the high coming on at 200*. The low is negatively grounded through a Derale fan controller that is adjustable. I have a 180* t-stat that is fully opened around 190*.

I did have to make special lower brackets for this rad and it is canted. Meaning the top is more forward that the bottom. I had to cut out and or bend the top of the rad support to get this rad to fit. Im running around 50/50 coolant and water.

So if you DO change to this set-up it WILL take some messaging.

The other things that might get overlooked.

Alternator voltage when both fans are running at idle. I have killed about 6 of the Summit 1-wire alternators, not knowing that a 100A alternator doesnt put out 100A at idle. I have a new billet 200A alt that puts out 140A at idle. Fans, not pulling hard enough.

The WP pulley is way too big.

Any brakes sticking?

Do the fans cover the entire radiator?

Mismatch gasket in the crossover? That can impede flow as well.

Size of the t-stat, high flow or stock. Im on the side of more flow is better. (Everytime at work we have an overtemp on a piece of equipment, 1st thing we do is check flow.)

Did I miss the lower hose? Does it have the spring in it?

Do the temps go down with the heat turned on?

Did I miss if this was an automatic? Tranny putting heat into rad?

One other thing that has been mentioned here is the gauge. I had to replace an electric as it was reporting too high a temp. Said like 215* but laser on crossover said like 190*.


Not sure if added anything you havent done, but more eyes are always better

[promptcritical]

Originally Posted by Squidward

I don't subscribe to the "too much flow" theory. In a closed loop system you have 2 heat transfer devices at work: Engine to coolant, and coolant to radiator. Assuming air flow is constant, heat transfer is mC(Tin-Tout). If you slow the flow, the Tout of the engine goes up to balance the equation.

When I used to run a reactor plant, there were a few things we did when we "put the pedal to the floor": Reactor cooling pumps went to fast speed, and the cooling pumps for the main condensers went to fast speed. Flow is good for heat transfer.

My 67 FB runs the Champion 4 core, factory fan, Hayden 2797 clutch, and factory shroud. I used to fight with cooling at cruise speed when I ran an electric puller fan that I thought was plenty adequate. And I also thought I would have plenty of air on the highway. But it could idle all day in the driveway, running the ac in 117 degree weather.

I changed to shroud, clutch/fan, and went from 2 core aluminum to 4 core Champion. Issue solved. I just got back from a drive an hour ago in close to 100 degree weather, and the gauge never got off 180.

I think it is your fan setup blocking air flow. Because you are achieving significant variability in operating temps with changes in ambient air temp, I think you are in need of more air.

Navy nuke eh Squid? Me too. Long ago though.

[Squidward]

Originally Posted by promptcritical

Navy nuke eh Squid? Me too. Long ago though.

Yup. I can still put someone to sleep discussing the different means to achieve critical heat flux. What flavor do you like, departure from nucleate boiling, or dryout?

It's been a couple decades, but every once in a while I still have a dream where I'm doing a fast recovery startup. It's amazing what stuck.

But it's also amazing that I can forget the name of someone I talk to once a week for seven years, like I'm de-evolving into a functional idiot with the changing of the seasons.

[Chris65LeMans]

Originally Posted by Squidward

But it's also amazing that I can forget the name of someone I talk to once a week for seven years, like I'm de-evolving into a functional idiot with the changing of the seasons.

I'm glad it's not just me...