my 69 is getting a little warm for my taste any suggestions. no question or suggestion too stupid.I will give you some background its a 455 block with edelbrock rpm heads,edelbrock rpm intake 10.62:1 compression.running a milodon allum. water pump,alluminum radiator with twin fans that flow 2800 cfm.am using a 180 thermostat and a 13 psi cap.have tried with a 16 psi cap.the engine seems to climb to 210 within probably 5-10 minutes of running my timing is 35 degrees total with 14 initial and 21 set in the mechanical advance(msd pro billet distributor) i want it to run cooler say 180-190. any tips or tricks to drop it down.the coolant mixture is gm dexcool/water 20/80 mix with red line water wetter.thanks for any and all help.Thanks
1st, is it brand new re build? it would run hotter at frst...
2nd, do you have all the fillers? like lower air baffle, the "masticated" or rubber fillers on ea side of bottom of radiator? and the most obvious , the X fillers...
also , how "hot" is too hot? You dont mention any temperature? also whats the outside temp ...? also, if running "lean" it runs hotter , you might richen it up some... is your fan working right? 1/2 in , 1/2 out of shroud? at 30 mph fan makes no difference ,so is it hot at idle or running at speed?
Here we have 88-92F now , my car runs at 195-200, goes up to 205 after a long run at 200 , when you stop at a redlight...maybe as high as 210....in July /August , when its 95-98F here its usually running at 210-215.....which is not too hot
Mine runs about the same 185-190 in 85dergree weather thats moving. Longer Stop and Go traffic 200 or 210. Take the center element out of the therastat. Slows the water down.
the temp right now seems stay in the 210-215 area and it shoots up there quick( in about ten minutes or less).i tried the 160 stat and that actually made things worse(220).i am not running a factory fan and shroud but instead twin electric fans and a sheet metal shroud.i have all the factory baffles under the hood at the core support and the lower air dam.i am running an open element air cleaner assembly.
Don't you have over 500HP? If so, it's going to run hotter than most others running at 325 HP. If you stay at 210-215 it's not a problem. It's when you climb to above 240 when you start to have issues.
Today's engines are tested with various methods similar to those back in the 60's. One being a thermal shock test running WOT 10 minutes at 240 deg, and shocked to 60 degrees in about 2 minutes or less, then 10 more minutes at idle 60 degrees, then WOT (peak HP or peak Torque)at 240 again. That's a standard test which is no worse than any road conditions unless you overheat (240 and up).
Make sure you have a 50/50 mix of coolant/water, more coolant will make things worse not better. Timing will also affect your temps .
Well I have over 500hp and it stays around 185 when I'm moving. The wife and I drove around at low speeds for a couple hours yesterday in the 82 degree weather and no problem. The fans keep it from going over about 215 or so. It does heat up fast, 36 degrees total and plenty of initial timing.
i have a 20% gm dexcool/80% water mix.i'm aware that 210 is decent and that modern gm engine most of them are optimum at 210 to 225 degrees but this thing climbs up to 210 in minutes and i am afraid to take it to cruises like this in fear of it getting hotter its not even that hot up hear yet.I think one of my issues is the car is to lean and i will mess with that tonight.one thing at a time that way it will be easier to pin point.right? thanks guys for the info i let you know if the temp changes by richening the carb.
This must an incurable problem. I have a 400 with ALL fillers, allum rad, 160 therm etc. and I still run hot 220. I even have the lower steel filler under the rad that most are missing. I have done everything possible and I still run hot. I am hoping that maybe with the new rebuild it will run cooler...
Sure seems to me there should be a resolution for all of us with this problem. Has this always been a known Pontiac issue? Is it possible that's just the nature of our beasts and there is nothing we can do? At what temp does this truly become a problem where serious damage occurs? Also, how accurate are the original style rally gauges (that's what I have and rely on)?
Jeremy, I have a similar combo to yours, with RPM heads and 10.5 to 1 compression, and I run mid-11's. Mine is 99% street driven.
I've had similar problems to the ones you describe, and just when I thought I've found the answer, the temp gauge begins to rise again! I've read dozens of articles on Pontiac cooling, and there is no one cure.
I can tell you what I've tried, what has worked, and what has not worked.
I run all the factory "400" baffles and dams (it's a factory 400 car, so nothing I had to do there).
I run a 180 thermostat, with a small hole drilled in the outer disc to alleviate excessive suction on start up (the famous collapsed upper hose problem).
A FlowKooler pump is a waste of money. The problem with our old Pontiacs is NOT the volume of fluid we're circulating. I learned that lesson about 5 years ago, and many fellow Pontiac racers have confirmed this. My wallet was $80 lighter, same problem. I went back to the factory steel water pump. Just make sure you have the correct divider steel plates behind the water pump.
I run a 2 row aluminum radiator (Summit Direct Fit version) painted black. I've tried electric fans only, and it's never worked. I've tried one of those massive Hayden stainless wide-blade flex fans (btw, those blades are VERY sharp), and while they pump a heck of a lot of air, the factory clutch fan worked the best.
I also run the factory fan shroud, which is still available from GM, or as a repro through a resto house like Ames. You're fan should be spaced so it's half in/half out of the shroud. I also run the factory w/p and p/s pullies.
I used to have an electric fan as a pusher, mounted in front of the radiator, and it was thermostatically controlled to come on at 190 degrees. This helped, but again, with a desire to stay with a stock look, I decided to pull it. The electic would come on a super hot days when stuck in traffic, and the temp would come back down to 190 from around 195.
I now run an 18" black thermostatically controlled clutch fan, available through Summit Racing. Looks stock, and pumps a heck of a lot of air. I had to shelve my factory 19-1/4" unit because I occasionally had some interference with the factory fan shroud.
One of the biggest changes I performed to cool the car down is that I went to full manifold vacuum instead of ported. I modified my vacuum advance can to pull full open at 5" of vaccum, so I get 36 degrees of timing even at idle (some racers have a locked out advance, and run 36 all the time). At cruise, I can pull 40-45 degrees of timing.
I also run Water Wetter and straight water, and I have a an overflow/recovery system with a 13 lb cap. The recovery system also helped quite a bit, as it adds a little bit more capacity to the system.
To recap my setup:
- 180 thermostat, with bypass hole - straight water, with Water Wetter - all baffles and dams in place - 18" thermo clutch fan - factory shroud, with fan located half in/out of the shroud - full manifold vacuum - 2-row Direct Fit aluminum radiator - overflow/recovery system - 13 lb cap - stock pullies
I second all of this with a couple of added comments; 1. I would figure out how to get the right diameter fan in there, 19.25" 2. I wouldn't use straight water because it can boil and evaporate quicker than coolant.(Many other reasons too)
Water Wetter also eliminates corrosion from aluminum parts, but if Water Wetter isn't used, Prestone makes an additive that prohibits corrosion too. With an aluminum radiator, aluminum heads, and an aluminum intake, I'm always careful about corrosion. Water Wetter works best with straight water.
Car is garaged, and only driven in Spring-Fall. Never had it outside when it was below 32 degrees. Can't get traction with salt on the roads.
Jim, have you ever been to this area for a show or drags before? There was a black 69 ragtop at the Cruisin' Tigers show last year, and it has me thinking of going to Starlight Black if I get my car repainted. The 69's look wicked in black.
I know a guy in New York that had water in his numbers matching 69 Z. He had only had it for a week and didn't know the previous owner had a leak and added too much water. Power outage and his block got cracked.
I haven't had my 69 done long enough to get it more than 100 miles away from home yet. Still chicken! I was going to paint mine red but changed my mind at the last minute because I had so many people telling me to keep it the original color. I'm glad now that it's black. I do get many compliments on the triple black. Mostly from the older crowd. The younger fans like the red TA much better. The only drawback I can see with black is it's a hot color. It's a great color for up north here but if I lived in the hot South I think it would get blistering hot!
When I purchased my convertible it had a 3 core rad and was missing the lower baffle. I upgraded to a 4 core and got a lower baffle. The only change was the temp remained more constant. I will be trying the trick of making the gap between the water pump impeller and the divider lesser. I will also be trying a factory 7 blade (GTO) flex fan to replace the factory 5 blade fan.
Originally Posted By Fbody69
I was going to paint mine red but changed my mind at the last minute because I had so many people telling me to keep it the original color. I'm glad now that it's black. I do get many compliments on the triple black. Mostly from the older crowd. The younger fans like the red TA much better. The only drawback I can see with black is it's a hot color. It's a great color for up north here but if I lived in the hot South I think it would get blistering hot!
I get more reactions from gals liking the triple black more than the guys. I saw one gal get weak in the knees when she saw me driving around up at PIB. I like black to, but hate to take care of it. If mine were Starlight Black and not its custom black/blue metal flake I'd be tempted to leave it.
With black you're constantly cleaning and dusting . Red is another color you have to care for; it does oxidize and turns pink.
1. Check water pump - the divider plate spacing could help 2. Check fan clutch - (I wish I had, that was probably my own biggest contributor to heat issues). 3. Add cooling - Aluminum radiator is pricey but can help 4. Check baffles 5. Check thermostat - leave it in - taking it completely out will not allow the coolant to cool-off while in the radiator. 6. Check timing - bad timing can add heat 7. Add an overflow catch tank if you don't have one. A big helper in radiator life span as well. 8. Make sure you have a fan shroud and that the fan is inside the shroud the correct amount.
Seems alot of people dont do any better with electric fans. Got tired of watching the temp gauge go...180-195-180-195-180. Dual Spal(sp) fans. Switched to a 19" Flexalite and factory shroud. Now it stays steady at 180-185* Never had a problem factory clutch fans either.
1. Check water pump - the divider plate spacing could help 2. Check fan clutch - (I wish I had, that was probably my own biggest contributor to heat issues). 3. Add cooling - Aluminum radiator is pricey but can help 4. Check baffles 5. Check thermostat - leave it in - taking it completely out will not allow the coolant to cool-off while in the radiator. 6. Check timing - bad timing can add heat 7. Add an overflow catch tank if you don't have one. A big helper in radiator life span as well. 8. Make sure you have a fan shroud and that the fan is inside the shroud the correct amount.
My two cents, Scott
#5 is theoretically possible on some engines but Pontiacs have enough constrictions built in that we are looking for more flow, not less. I know this because I've tried it with and without a thermostat on a few engines. They either cool better or stay the same without a thermostat. On a Pontiac v-8 the thermostat is only useful to quicken the heating up of the engine.
I had a guy tell me to remove the rear freeze plug on the driver side head & then T a fitting in with the heater hose on the passenger head. This allows water to flow freely through the driver side head. Don't know if it works, just a thought.
it works ,seen it done , but doesnt get temp much down , but more even flow...I thought of doing that at one time ,but after the info I got ,didnt seem worth it....
I Had a similar problem with my 400/373 gears the lower I ran the thermostat the worse it got. I put in a 190 degree thermostat and the car runs at 190-195. Regards The Bird Hangar
No, not a chance. I've run all my Pontiac with and without thermostats and they always run cooler without any thermostat at all. Can't argue with results. This all sounds like 'inconsistancies' with engines, conditions, ect.
had to reread this thread ,took the car out tonight for 20 minutes got home and the rad boiled over,guess i need to get a shroud for starters,also have no baffles,might try pulling the thermostat.i should have checked the divider in the water pump when i had it off this past winter but i aready had it together when i read i should check it.oh well
Okay, some simple physics. The amount of cooling that the radiator can provide depends on the difference in temperature between the water and the air going through the rad. If the water stays in the rad longer it will get cooler, but the amount of heat given up by the water will be less because the temp difference is less. Having a higher volume of water through the rad increases its cooling capacity. Having a restriction before the rad makes for more pressure in the engine to allow a higher boiling point on the water but slows down the flow. Increasing the efficiency of the water pump provides both higher flow and higher pressure. Increasing the flow of air through the rad improves cooling as well by increasing the temperature difference between the air and the water.
The engine will be cooler for longer without a thermostat but if the rad isn't big enough or doesn't get enough air the engine will still overheat. It's better for the engine to get it up to operating temp quicker so I always run a thermostat on the street and sometimes on the race track depending.
Here's a silly question.. What octane fuel are you running? I had a similar problem with my 400 + .030 & #13 heads accordingly a static CR of 10.36. I started putting 94 octane in from 92 octane and dropped a good 10d. I have a fixed fan and a poor excuse for a shroud currently and run a solid 180d and creap to 190d when idling for a long time.
I like black to, but hate to take care of it. If mine were Starlight Black and not its custom black/blue metal flake I'd be tempted to leave it. 
