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cortcomp
Coyote

USA
5338 Posts

Posted - 27 Aug 2010 :  11:14:06 AM  Show Profile  Visit cortcomp's Homepage  Reply with Quote
Hello All! After finally getting on the road with my 71, i started to fine tune things that were bothering me and so i thought i'd ask some questions about water temp.

I have a 428 with milled 6x-4 heads, aluminum radiator, 160 deg high flow stat, high flow water pump with divider plate clearanced, exhaust crossovers blocked off from going into the intake, and a 6 blade flex fan. (this style blades: http://www.summitracing.com/parts/SUM-G4918/?rtype=10 ) Temp sender is next to the thermostat in the water crossover.

With this setup i was running at 165-170 degrees constant. A/C on or off. Up hill or down. Day or night. Idle in 100 degree heat or cruising down the highway. Fan was quiet as can be. (i almost never heard any fan noise)

While chasing down different things and asking questions about my car and chatting with other pontiac enthusiasts it acme up that the stock factory stat is actually a 195 and one guy actually pulled out an old tech bulletin from pontiac in the late 60's that basically said don't switch thermostats, we want this engine running at 200 degrees for optimal efficiency, and running a cooler thermostat could cause over heating issues in some specific cases. Put a 195 back in the car and test cooling system again.

Made sense to me because when i tore my engine back down after about 700 miles to witch to lower compression heads (and because my valve seals were a bit shot) i noticed some gunky buildup on the pistons (not all carbon, it wasn't that dry. You could kind of smear it with your finger, it wasn't all the way dry and charcoal dusty like carbon). Rest of the motor was clean as can be, so i chocked it up to the valve seals burning some oil. Cleaned them up and put back together. Fast forward now and i'm thinking i'm running too cold and maybe that stuff should have burned off even if there was oil getting in the chamber. (Pistons have new rings and i have no smoke or indication of oil burning now, nothing on spark plugs or anything.)

I put on a new Hayden clutch fan (that they show for our application, not just some random clutch) and a 5 blade fan for it and the first thing i noticed was that it was A LOT louder at highway speeds and even just cruising. (attributing that to the aftermarket new fan. It has evenly spaced blades, and i thought the uneven OEM blade spacing made for a quieter fan? I'll have to get an original one. The flex fan did have a slightly uneven spacing to it, which may have been why it was so much quieter. I'm so frustrated that direct replacement parts aren't actually direct replacement. Always louder or has more play or needs modified to fit. That's a different thread i guess.)

I also thought it would let my temp come up some by coasting when the engine was so cool but it didn't, stuck at 160 as before. So finally i had to switch radiator hoses and took that time to switch to a Stant 195 stat. Car runs at 200 perfectly like it did at 160. No wavering, no creeping with AC on. Same at idle and cruising etc. However, it did seem to drive just a little smoother off idle when releasing the clutch or throwing a full throttle run at it. Can't prove it, it just felt smoother and less temperamental. However, i do have to retard the timing some (have 18 initial) as when it's fully warm i can get it to stumble for a second by just dumping gas to it and being in a higher gear. It didn't do that at 160 degrees. It still has the e-carb on it so honestly it just might be that the carb isn't right for the motor and this temp. 6 months from now i can test that when i get a cliff carb. No knocking or pinging at that timing setting, i just feel a couple degrees back, at this temp, would be perfect for drivability.


I don't really have any questions or issues here to solve, just wanted to start a discussion and get some opinions for general knowledge and report real hard data about cooling with the specific setup i have and what effects each change has had. I don't see a problem running it at 200-205, i think it would be more fuel efficient and responsive, especially if it's staying there and not creeping or rising and falling with driving conditions. I seem to have the car doing great in the cooling department where i can pick my operating temp reliably within about 5 degrees by switching thermostats.

Whats everyone's take? Can you be too cold and get performance or economy issues? Maybe not getting the motor hot enough helped contribute to oil sludge buildup on top of my pistons before? Need a richer fuel mixture because it's always cold at 160? Less general engine efficiency? I know there's not a lot of difference between say 180 and 195, but 160 to 205 is a 40 degree change! Just filled the tank after the change, and I've been getting about 14.7mpg now, so i can get a MPG estimate when this tank is gone to see if that changes at all. With 3.5 gears and .70 overdrive, i hope to hit near 25mpg when i get a carb from cliff, but i can still play now with the e-carb and see how the motor responds to minor changes and tweaking.

mike389
Big Trees

USA
568 Posts

Posted - 27 Aug 2010 :  4:35:07 PM  Show Profile  Reply with Quote
about your 5 blade fan, i have a 7 blade aluminum fan W/blades unevenly space (19.5" dia.)for quiet op. i found it at an classic auto wreckers i believe off a '65 or 66 A/C Pontiac wagon,and other GM's will be the same the blades are ridged and for my car worked perfect and polished up nice to go with rest of engine bay, if you don't care about a clean engine bay that part is moot! if you stay with clutch set up it would be worth looking for, hayden might have a 7 blade check your parts store's!! also the 190 stat is listed in motors manual from 1966 thru 1969 so 70's are probably 195! the engine does run more efficient at 190-195. my mpg last two fill ups were 17!! the one key in all this is don't let the cooling system boil over!
mike
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cortcomp
Coyote

USA
5338 Posts

Posted - 27 Aug 2010 :  8:30:13 PM  Show Profile  Visit cortcomp's Homepage  Reply with Quote
I was thinking of hitting the junk yard just for fun anyways....it's been awhile! It hasn't boiled over yet, but i do have an overflow tank so i'll have to keep an eye on it and see if it looks like it is. I didn't see a 7 blade fan new for this setup, but then again i'd rather have an old OEM one anyway, the new stuff doesn't seem to behave in quite the same way.

Someone here said they had a 4 speed and with one of cliff carbs were getting 21mpg...with overdrive i'd love to see 25!
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mike389
Big Trees

USA
568 Posts

Posted - 27 Aug 2010 :  10:52:17 PM  Show Profile  Reply with Quote
i have a 600 cmf edelbrock 1406 on a 389+30 mild build and get 17, waiting for my Q-Jet from Cliff, hopefully mileage will improve!!!!!!!
don't restrict yourself to Pontiac if you can find a fan off a cad.,olds,ect it's the same unit if there are no Pontiacs available, good luck
if it boils over you hear it puke water for a few minutes!!!!!
i use one gallon antifreeze the rest distilled water, which keeps the hard water build up out of radiator!!!!!
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cortcomp
Coyote

USA
5338 Posts

Posted - 28 Aug 2010 :  09:27:11 AM  Show Profile  Visit cortcomp's Homepage  Reply with Quote
I think the edelbrock primaries are too big and not only slow incoming air velocity but also are just too big for cruising. If that theory is correct then maybe the smaller q-jet primaries will be the ticket into the 20s!!

I might have time tomorrow to pick around some yards and see what i find!
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455 Formula
Sitting Bull

USA
244 Posts

Posted - 25 Jan 2012 :  12:13:50 PM  Show Profile  Reply with Quote
Nice post, lots of good details....

I didn't run a thermostat in any of my cars for over 20 years, we always just ran a hollowed out thermostat body. The biggest reason for this was we kept running into bad thermostats and the climate where we lived never got down under 40 degrees and the summer temps were way up over 100.

Recently, we moved and I found it necessary to run not only a thermostat, but also switch to 10w30 oil, since it has been down in the 20's at night. The 180 degree thermostat seems to work fine in the 413 and I don't notice any real difference in how the car runs regardless of the coolant temperatures. I figure this is probably due to the car having the functional ram air system...FWIW.
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cortcomp
Coyote

USA
5338 Posts

Posted - 25 Jan 2012 :  12:27:14 PM  Show Profile  Visit cortcomp's Homepage  Reply with Quote
I've run no thermostat in different trucks or beaters or whatnot over the years, and had vastly different experiences. With a 91 GMC, SBC 400, 2bbl carb (butchered job all the way around, ran great.) 5speed 2wd, no thermostat meant NO heat. Even after driving for hours in the winter, the temp wouldn't even register on the gauge, and you didn't even get lukewarm heat out of the vents. A 160 thermostat solved that.

We had another 80's car, forget what it was, monte or cutlass or something, and no thermostat meant it would overheat. I don't know if it was the old explanation that the coolant didn't stay in the radiator long enough to cool or what, but a 180ish stat went back in and it ran like normal.

Go figure.
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455 Formula
Sitting Bull

USA
244 Posts

Posted - 25 Jan 2012 :  3:58:36 PM  Show Profile  Reply with Quote
Some cars just react in strange ways.

My 413 runs much, much better with the exhaust crossovers open, and not just at cold temperatures, but even when its hot...Robert

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455 Formula
Sitting Bull

USA
244 Posts

Posted - 25 Jan 2012 :  4:42:02 PM  Show Profile  Reply with Quote
FWIW,

I got a beautiful (and new) AC Delco HD fan Clutch and 7 blade fan that will make my Formula run 210 to 220 all the time, regardless of ambient temperatures, presence of a thermostat, 3 or 4 row radiator, etc.

Went back to my Lincoln 7 blade flex fan and you can watch the temp fluctuate as the termostat opens and closes, varying between about 165 and 185 degrees, even when it is well over 100 degrees outside...Robert

Edited by - 455 Formula on 25 Jan 2012 4:42:42 PM
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