Ive been fighting this since I assembled the car. everything is all new, aluminum radiator , new thermostat, 2000CFM electric fan. runs 230 to 240 all the time, today I noticed the temp gauge was pegged, pulled over to let it cool sounded like an old coffee percolator. I've done the water pump to the plate trick and got the plate close as I could without touching. engine runs great tons of power, etc. only thing I haven't replaced is the wp itself.
It's a 69 400 XX code block ,.030 over, CR around 9:1 heads are #16 SS valves pocket ported. Basically its the 068 GTO cam. Big block 7/16 rocker studs. Cast impellor ,
I cant say for certain I have burped it , I have filled , run, filled , etc. Until I thought it was full.
No mechanical fan , just a electric puller fan 2000cfm and its definitely pulling. I do have the x baffles.
im running 10 degrees BTC @ 650 RPM idle. but it will run hot doing 55 MPH.
Are you sure your distributor is coming in at the right RPM, not hanging up? Curved properly?
Not saying that is what I think..
I have always had issues with over heating even with a puller fan. A couple of problems I had. Clearance with divider plates/water pump impeller, fan type and clearance to shroud. Excessive/inefficient sealing of shroud to radiator, Air pockets in block. I jacked the front end of my car 8-12" and allowed the air to find its way out of an open radiator.
2 core aluminum? stock dimensions (l/w)?
Si Vis Pacem Parabellum
1967 Starlight black PMD Engineering 400 Auto 1968 Alpine Blue 400 4 speed 1968 Verdoro Green 400 HO 4 speed 2013 1LE 2SS/RS Inferno Orange Camaro.
2 core aluminum pretty much stock size it a little taller than stock. I spoke to summit and they were positive its more than enough for the engine. The fan is 17 inch and is a bout 1/8 inch away from the rad fins. if I went any closer the fan would hit the tubes.
If memory serves me correct, I believe that is way too close. I have a stock declutching fan and stock radiator. I have 4.15" from fan clutch face to the back side of a 4 core radiator.
I digress..was doing other stuff and my ADD kicked in. the electric fan spacing is fine.
Compensating for the clutch, I say the fan is appx 5.25" away from the core.
If you are ONLY using an electric fan, as I did with aluminum radiator, that will not work. You will have to supplement the puller/pusher electric with a flex fan/shroud.
I ran a stock 7 blade belt driven flex fan and wasn't enough. I then went to a puller electric in front of the radiator and solved the problem.
I might suggest a dual fan setup. would cover more area at a higher speed/air volume.
all the electric fans I've seen stock or after market are right on the rad. I would totally agree if my issue was only around town or slow speed. But after 20 or 30 MPH a fan is useless. the very reason manufacturers went to electric fans. The mechanical drain mileage and HP at speed for nothing. My 62 impala SS 350 had a mickey mouse electric setup and never overheated just sitting in traffic. it seems more like a flow issue than anything.
all the electric fans I've seen stock or after market are right on the rad.
Yes, I digressed. 1/8" is fine. I confused my response to you with a PM....I apologize.
The efficiency/effectiveness is based on rating of fan. If you have a light or medium duty single fan and it's not cooling, You will have to go to a super duty fan. I believe same dimensionally as far as height and length, but deeper.
Si Vis Pacem Parabellum
1967 Starlight black PMD Engineering 400 Auto 1968 Alpine Blue 400 4 speed 1968 Verdoro Green 400 HO 4 speed 2013 1LE 2SS/RS Inferno Orange Camaro.
my issue isn't ADD its just old age ;-) btw its a th200-4r connected to 2000-RPM stall converter into a 3:55 posi. the trans is a built unit from a company in PA.
ya true. I looked mine up its 17" 2500 cfm hi performance fan.i can add a 14" pusher in front to increase the flow . My controller will handle 2 fans. BTW I sense the temp at the thermostat, not at the radiator.
But the stock fan was 19.5 ", I ran a flex fan 17.5 and my temp was always at 230deg, I tried the electric and it wouldn't cool her down, I found out my timing had to be at 12-14 deg BTC and she ran cool. It was the timing and my backplate had to much clearance behind the water pump.
I agree with ragu. My car had some issues once I finished assembly. Found all things add up to success. initial at 12 and 34 total. vac adv from a ported source and HD hayden fan clutch with an AC style 7 blade fan and shroud. also put in a smaller waterpump pulley to drv fan/pump faster. with a 180 stat it hangs at 185-190. will climb sitting in traffic to 195 and quickly drop once moving. Ran her this weekend and it was 96 and humid. Also all all dams must be in place on our first gens!!!!
Dont feel bad my buddies TA has killed three high torque starters due to heat, he loves those 4 tube headers though!!!
Gerry, I was thinking about running a smaller WP pulley to get more speed/flow from the WP. I have power steering what pulley did you use ? The distributor is pretty much stock with the exception of the pertronics conversion.
What pulley did you use Gerry on the water pump? Mine is still that stock. PCI my dizzy is all stock except for the points conversion kit, I run her at 12 and get around 34 total adv. and run her on the ported side too.
Are you running an external cooler for that trans? Those things run real hot and will add to your heat issues if using an internal rad cooler. Do you have an overflow can? Your engine setup sounds the same as mine. I run a 160 stat and it hardly ever gets above 170. If the outside temps get high it does run a bit hotter but never goes over 200 unless nit's out of water. I run a brass 4core with a 7 blade flex fan.
I concur on checking the timing. Are you running manifold or ported vacuum? Running manifold vacuum will cool the engine down. The more vac advance you can pull at idle and part throttle, the cooler the engine will run.
Also, check to make sure you're not collapsing the upper or lower radiator hoses. I put springs in both my upper and lower hoses. The lower spring is usually the culprit, but on Firebirds, they use a very long dogleg upper hose, and sometimes they will collapse (or partially collapse) at the water neck 90 degree bend area due to the weight of the hose when filled.
You can also drill a small 1/8" hole in the thermostat in the outer disc area to allow some bleed through when the car is turned off. This usually eliminates any air pockets from the heater core area.
I always thought when I had my engine rebuilt I could run the engine off the full manifold vac. source for the vac. adv. I actually found from talking with others I am no longer stock and using a aftermarket cam I needed to bump the timing up to 12 BTC and use the ported vac. source for my vac. adv. When I was using the full man. vac. source and she'd run hot like the timing was retarded not knowing that the cam I had needed to be adv. some to get the performance it has to offer, so I left it there and drove it like that for 3 years and went through 2 carb's new and tested 10 others on her to find that it was always a timing issue not the carb's. There has always been a discussion about the pros and cons of using full vac. source and ported sources for vac. adv. and both sides have there good points but I found I was having a problem running full manifold vac. My engine was running hot and sounded like it was loading up at idle, when I bumped the timing up and went to ported the engine had better performance and ran a little cooler, to think I listened to the engine builder and ran stock timing for 3 years and the car after that wouldn't drive 10 miles before having to pull over and let it cool. I also heard about drilling an 1/8" hole in the thermostat, does that really help?
I would get an adjustable timing light. You need to find out exactly how much timing you're running, both mechanical and vacuum. Sounds like your distributor and/or vac advance may be the problem. With an adjustable light, you can determine how much vacuum you have (mechanical) by unplugging the advance (plugging the line), then rev the engine to 3000 rpm and check the total mechanical timing, then do the same with the advance connected. You could have advance weights that are hung up or stuck.
With your combo, you shouldn't have any overheating issues.
I would ditch the electric fan and use a factory clutch fan, or a Hayden aftermarket clutch fan, either the standard duty or heavy duty version. The electric fan is a nice helper (maybe you can mount it front of the radiator), but it's not enough to cool a big Pontiac. Regardless of what the manufacturer claims (they want to sell electric fans), the factory clutch fan, and factory setup, is the best.
Mike , I had an electric "helper fan" on my hot engine when i bought it...it actually blocked more air and at speeds ran hotter..I gained almost 5 F by removing it...it might help on idle...but...no pusher fan in front of engine would be my advice...I run stock fan...after many improvements I reduced my temps from 230 to 190, little by little
a friend with supercharger and no room has 4 electric 'puller'fans , two larger ,two smaller inset in an alum. shroud to cover almost entire radiator area..to get as much air as possible...
I too had an electric pusher a long time ago. It does prevent full air flow from entering the radiator fins, but the electric fan freewheels, so it doesn't actually block air. But it does have a slight effect on airflow white at cruising speeds. Just acts like diffuser, preventing air from going directly from the grille openings into the radiator.
The electric pusher works really well at low speeds, especially sitting in traffic, as it moves enough air, while idling, to simulate the car going 20-30 mph (approx).
Also, the electric pusher does wonders on those hot days when you have to shut the car down for 5 minutes or so, such as when getting gas. Typically, without any electric pusher, when you go to start the car back up after a 5 minute hot soak, the tempo gauge is usually 5-10 degrees hotter. Allowing an electric pusher to run while the engine is off usually eliminates that problem.
You can also try pulling the thermostat. Many people believe that makes the car run hotter, but people that have tried it know that it does make a difference, and the engine runs cooler. I've run one of those restrictor plates (Moroso) before, which is just a thin disc that's replaces the thermostat, and it has a hole in the middle. Works the same as if you hollowed out your thermostat. Your car will take longer to warm up, but eliminating the thermostat does seem to work on our old Pontiacs, most likely because our cooling systems aren't very strong and the coolant does not cycle very fast.
Water Wetter, used with straight water, also works. I've tested that stuff many times, and it does indeed drop the temps by 5-10 degrees.
The total timing (initial plus mechanical) at 3000 rpm should be 38 degrees (or close to it).
Now with the vacuum advance hooked up, again rev it to 3000 rpm. Vacuum should be anywhere from 40 to 50 degrees.
At idle, check the timing with the advance hooked up. With your 10 degrees initial, you should pull 20-25 degrees total at idle (this is of course using full manifold vacuum, not ported).
So Stealth I should be at 10 deg BTC and on full manifold vac. not on 12 deg and ported? She's still a little warm around 200 with an 180 Thermostat in her. Because when I drive through town and hit a light or 2 she sounds like it's gonna stall but it doesn't.
Here we go again... Anyone that drove cars back then knew normal operating temp was(and still is) 210 w/a 195 stat. Don't believe me, do a search for test drive articles from that era. No one got concerned unless they went higher then 225-230.
From 76-79 my FB w/11.5 cr, 255/263 sft, and 195 stat ran 220 w/o any probs. In fact the fastest times at drag strip where at this temp. Factory shroud, factory 4 blade fixed fan, standard radiator, and NO upper covers. Did have lower valance.
negating the temp, and it is over 230 it boils over and over heats, city OR hi-way. Yes the system is pressurized, that's why I'm leaning toward the pump/flow Like I said earlier my 62 Impala SS with a 350. never over heated and believe me the electric fan was and still is mickey mouse.
Yes, but they run better when the temps are around 190 degrees. I would rather have a temp gauge in the middle between cold and hot (at around 190-195 degrees) rather than having one that was at 230-235 degrees, or 5-10 degrees away from boiling over.
The Detroit manufacturers discovered things as they went along, so old road tests aren't the best reference for determining what the engine temp should be. There was an old test of a 1970 Buick GS Stage 1 that was conducted in hot weather, and the car boiled over after every run. Not my idea of a fun day at the track. By 1971, GM introduced closed cooling systems on nearly all of their cars. Before that, Americans were used to having coolant spewing out of their overflow tube on hot days after they shut the car off.
Along came closed systems, clutch fans, and full fan shrouds. When you compare a 1965 GTO system, which had a fan guard (no shroud), overflow tube, and a top tank radiator, those cars were notorious for overheating. But by 1972, they had a closed system, full fan shrouds, clutch fans, and the overheating problems were resolved.
Yes I do have an over flow tank. I'm going to try all the simple stuff first before going nuts on it. I had an 88' fiero that if you didn't jack up the front of the cat to fill the cooling system. You would never get it full. So I'll try the burping, timing etc. I'll find and fix the issue, I just like to vent too...lol
My 69 GTO was almost identical to my brothers 69 Chevelle SS, as far as radiator, fan. under hood, body etc. But the 396 had main bearing clearances greater than the clearances in my 400. His ran cool mine ran hot. I don't know if I go for that close clearances equal hot oil or not but I was always fighting high temps and he just put the foot down and didn't worry about it. We seem to have more problems than the Chev guys, and the rads, fans, hoses, heater cores and what have you seem to be of the same breed but we always have that temp problem???
The more heat and engine can tolerate, the more power it will produce. Anyone tells you different doesn't know thermodynamics.
Absolutely! The hotter the combustion chamber, the more power you can produce. In all forms of racing, they run the maximum amount of heat in the engine they can. I think the NASCAR boys run around 230-240 all the time, but they're also looking for that extra 1 or 2 hp over their competitors, and they have unlimited budgets if they blow up an engine. Those NASCAR radiators are $10,000.
I would say that part of the problem with heat in Pontiac engines has to do with their exhaust port design. Not the best flow, but adequate for a cruiser. Problems arise when aftermarket cams are used, which typically increase the intake/exhaust lift and duration, but the Pontiac exhaust port is simply not designed to flow more than its original design parameters without knowing how and what to port.
The basics, using factory designs, will work. A GM clutch fan, closed cooling system (post-1971 style), correct timing, good water pump, and if you throw in an aluminum radiator, that should work for 99% of the Pontiac setups out there.
I run an aluminum radiator, Hayden 18" thermal clutch fan, straight water + Water Wetter, stock shroud, stock baffles, stock water pump, manifold vacuum, modified distributor vacuum advance to pull 36 degrees at idle, and a regular thermostat (hole drilled to eliminate air pockets). I stay at 190 degrees all the time, occasionally going to 195 on 90+ degree days while sitting in traffic or after a hot shutoff.
Last 2 posts are good. FWIW, my current w/p has stamped impeller(needed asap/only type could find) but seems to work fine. Rest of setup;
10.2cr(needs to be 11.0) 230/240 hft 19-15/16 flex fan with shroud 180 stat(cause 175 shot n2o sometimes) Rodney Red radiator Valance with no upper baffles Idle gets to 195 when 90* out
