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#1
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69 FB 400 cooling goofiness....any ideas?
I've got the goofiest problem with my cooling, maybe someone can enlighten me.
69 400, 400 CID, 9.5:1, stock 62 heads, TH2004r tranny, stock manifolds with factory A/C, P/S, alternator. It's the early 69 4" water pump (stock AFAIK). Changed the thermostat to 160 high flow, changed the fluids in November (maybe 500 miles on it since that), no hose leaks, no water leaks I can find, overflow tank is not missing any water, level has stayed the same. Termperature gauge has been checked, temperature sender as well. The gauge reads what an infrared scope says the temperature is at the thermostat/top radiator hose housing. Lower radiator hose reads about 40 degrees less than the top hose typically (215 top, 170 bottom). Aftermarket aluminum radiator, 20" electric fan, fan relay turns it on around 150 degrees, I do have a tranny cooler, but it's not in the way of the radiator getting air. The radiator was new 3 years ago, and I just had the antifreeze changed. If I drive on the street to my friend's house it's about 12-13 miles. The car never goes over 170/180 degrees, stop and go traffic, top speed probably 40-50, with the occasional punching of the gas pedal as traffic/police permit. If I drive on freeway to his house it's about 14-15 miles, I'm going 75mph, turning around 22-2300 rpm and when I get there the car is at 210-220 degrees. What the hell? Maybe I'm just nuts, but wouldn't there be more air rushing through the radiator shroud/fan and over the engine at 75 mph than 50 in stop and go traffic? I'm changing out the water pump, hoses, and belts next week as it's the last thing in the cooling system that hasn't been upgraded. Anyone else had this weird problem? TIA for any ideas of why the Bird is doing this! Jim |
#2
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Does the fan shroud have air baffles or reliefs? If it's a flat shroud that encapsulates a single fan, it's actually probably blocking airflow at those speeds.
The shroud needs to have reliefs in it to allow air to flow through the radiator. At speed, the fan itself may be acting as a restriction as a result. Other possibilities include a lower rad hose that is collapsing at somewhat higher rpms and not allowing proper coolant flow.
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-Jason 1969 Pontiac Firebird |
#3
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Is your vacuum advance on dist hooked up and working properly?
Sent from my SM-G965U using Tapatalk
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68 Firebird-- Street/Strip - 400/461 Eagle Forged Bottom End & Ross Flat top pistons. KRE 325 CFM D port, Ultradyne 263/271 @.050, .4267 lift. Crower Solid roller lifters and 1.65 stainless rockers. Quickfuel 1000 on Torker2 intake and 2" open spacer. Hedman 1.75" headers. TH400 w/brake. Ford 9" w/3.80 gears & 28x9 Hoosier pro bracket drag radial. Best ET: 1.35 60ft, 6.29 @ 107.20 mph, 9.99 @132.33 mph. 3,300 race weight |
#4
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Pic of the fan shroud and fan. The fan moves easily when not engaged, so I have to figure if it's not on that air is getting through, and likely moving the fan as well when it flows through. The shroud doesn't have any relief air holes, though.
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#5
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Yes, I had an all new Sean Murphy Induction Stage 2 Q-Jet installed in November and he went through and checked all of that.
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#6
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"The shroud needs to have reliefs in it to allow air to flow through the radiator. At speed, the fan itself may be acting as a restriction as a result."
I am thinking this as well. My 66 had an aftermarket shroud and dual electric fan and similar to yours would run hot at highway speeds but fine at idle and cruising around. On that car I went to a factory 7 blade clutch fan and all was fine. My current setup uses a Lincoln Mark8 electric fan, which pulls a ton of air and has no issues at any road speed. Sent from my SM-G965U using Tapatalk
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68 Firebird-- Street/Strip - 400/461 Eagle Forged Bottom End & Ross Flat top pistons. KRE 325 CFM D port, Ultradyne 263/271 @.050, .4267 lift. Crower Solid roller lifters and 1.65 stainless rockers. Quickfuel 1000 on Torker2 intake and 2" open spacer. Hedman 1.75" headers. TH400 w/brake. Ford 9" w/3.80 gears & 28x9 Hoosier pro bracket drag radial. Best ET: 1.35 60ft, 6.29 @ 107.20 mph, 9.99 @132.33 mph. 3,300 race weight |
#7
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Quote:
Quote:
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#8
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I don't think the shroud is the problem. That fan is 19" iirc and has plenty of open space for air to flow through.
The first thing I would do is to make sure that there is a spring in the lower radiator hose to keep it from collapsing at the higher RPM's. When it comes to cooling, faster flow equals better cooling. Try removing the thermostat and see if the engine still runs hot at speed. This made a HUGE difference on my bird. Knowing what your oil temps are would help. It's possible that at the higher RPM's, the oil temp is climbing and adding more heat to the engine. I had that problem in my '67 with a 455. Which oil are you running? If the clearances are good, 10w-30 should be all you need. Anything over 12-15 psi at idle & 10 psi per 1000 rpm is fine. As mentioned above, Timing.... Other things that help are the upper & lower baffles that came in AC cars to help direct airflow to the radiator. I also added some of the black foam, water pipe, insulation that you can find at Lowes/Home Depot between the radiator and radiator support so no air escaped around the radiator. If you have a spring in the lower hose and removing the thermostat doesn't help enough, you may need to remove the water pump and verify that the divider plate is as close to the pump vanes as possible. I try to make mine no more than around .030". It could be up to a 1/4" away if it was never clearanced.
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No! Do not try! Do! Or do not. There is no try. - Yoda 1967 Firebird Restoration 2005 - 1/25/2017 |
#9
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Regarding the timing topic... my old 455 with a relatively small cam and iron heads really wanted the advanced timing at cruise or would overheat quickly. At the time I think it was running 36 deg mechanical advance and the vaccum canister would add another 10-12 degrees at cruise.
Meanwhile my current build with twice the HP and KRE heads with 28 deg of mech advance seems to care less if the vacuum advance is connected or not! I assume the current combination of parts is simply working better together Sent from my SM-G965U using Tapatalk
__________________
68 Firebird-- Street/Strip - 400/461 Eagle Forged Bottom End & Ross Flat top pistons. KRE 325 CFM D port, Ultradyne 263/271 @.050, .4267 lift. Crower Solid roller lifters and 1.65 stainless rockers. Quickfuel 1000 on Torker2 intake and 2" open spacer. Hedman 1.75" headers. TH400 w/brake. Ford 9" w/3.80 gears & 28x9 Hoosier pro bracket drag radial. Best ET: 1.35 60ft, 6.29 @ 107.20 mph, 9.99 @132.33 mph. 3,300 race weight |
#10
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It appears you are running a Ford Taurus or Lincoln Mark VIII electric fan.
What controller or wiring set up are you using for it and how does it turn on ? |
#11
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I suspect the water pump and divided plate have not been clearanced properly. But I haven't checked the lower hose for a spring yet. Since I'm getting new GM hoses the new ones should have that spring in the lower hose.
I ordered a new Flowkooler high volume pump to replace the current one, so hopefully with all those parts it will make a difference. I didn't buy this car to go 50 mph and under! |
#12
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I can't read what the fan is exactly, I just measured the opening at 20" so it seems to be a 19" diagonal, which has two speeds triggered by the Flexalite controller. I checked my SMI receipt, the timing is 34 degrees at 2200 rpm, 20 degrees of vacuum advance, Stage 2 Q-Jet with Jet 7.5, Rod: 46K |
#13
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Would be interesting to see how a shroud like that works with air flappers reliefs in it. At low road speeds the fan would pull them shut and pull air through the radiator, at high road speeds positive pressure would open them up and let air flow through freely.
I'd lean towards an air flow problem .... the big difference between low road speed and high road speed is that at low speed the fan PULLS air through the radiator, at high speed positive air pressure in front of the radiator PUSHES air through. With a box shroud at low speed the fan draws a vacuum on the entire box, effectively using most of the radiator (as long as the offset from fan to radiator is enough). At high speed air enters the entire front of the radiator and then must pressurize the box and escape through only the fan opening in the shroud. A tapered shroud would probably help a lot, it creates a pressure gradient at speed which directs the air toward the fan opening. All this assumes the water pump is operating as it should of course. I'm a big fan of the OEM shroud and fan ... does cost you some HP, but extra HP isn't much good if the engine is too hot to use it. |
#14
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I ordered a new Flowkooler high volume pump to replace the current one, so hopefully with all those parts it will make a difference.
If this does not fix it, you may want to purchase or make a couple of coolant restrictor washers. They of course replace the thermostat and would allow you to experiment with different flow rates to find the sweet spot. It is a little frustrating as it looks like you have been covering most of the basics! Sent from my SM-G965U using Tapatalk
__________________
68 Firebird-- Street/Strip - 400/461 Eagle Forged Bottom End & Ross Flat top pistons. KRE 325 CFM D port, Ultradyne 263/271 @.050, .4267 lift. Crower Solid roller lifters and 1.65 stainless rockers. Quickfuel 1000 on Torker2 intake and 2" open spacer. Hedman 1.75" headers. TH400 w/brake. Ford 9" w/3.80 gears & 28x9 Hoosier pro bracket drag radial. Best ET: 1.35 60ft, 6.29 @ 107.20 mph, 9.99 @132.33 mph. 3,300 race weight |
#15
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Well, being in So Cal, a lot of my local Pontiac friends run with no thermostat. If the water pump/hose/divider plate/etc doesn't fix it, I'll take the thermostat out next and see if that does the trick.
I'm sure this will be an adventure! |
#16
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While I do not have any scientific data on this, many will say that water mixed with an additive like water wetter ( I use hyper lube brand) will cool more effectively than antifreeze, while still providing rust protection and water pump lube. Of course not a magic bullet but could help a degree or 2.
Although I live in MN, I only run the hyperlube with straight water- as the car is kept in a heated building Sent from my SM-G965U using Tapatalk
__________________
68 Firebird-- Street/Strip - 400/461 Eagle Forged Bottom End & Ross Flat top pistons. KRE 325 CFM D port, Ultradyne 263/271 @.050, .4267 lift. Crower Solid roller lifters and 1.65 stainless rockers. Quickfuel 1000 on Torker2 intake and 2" open spacer. Hedman 1.75" headers. TH400 w/brake. Ford 9" w/3.80 gears & 28x9 Hoosier pro bracket drag radial. Best ET: 1.35 60ft, 6.29 @ 107.20 mph, 9.99 @132.33 mph. 3,300 race weight |
#17
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Pulled the Bird apart last night. Took the water pump off. Previous owner forgot to put in the Timing Cover to Water Pump Sleeves w/Rubber O-rings!
So the water pump wasn't getting the water circulated into or through the block properly. Argh! |
#18
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Impressive that it didn't overheat around town put together like that.
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#19
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My brother had the same discovery with a 461 he had an engine shop build. Car was chronically overheating, so he thought he'd swap out the water pump. Took it apart and found no sleeves and a single rubber o-ring gasket sitting on the bottom of the timing cover. Needless to say, he won't be using their services again.
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1966 Pontiac GTO (restoration thread) 1998 BMW 328is (track rat) 2023 Subaru Crosstrek Limited (daily) View my photos: Caught in the Wild |
#20
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Quote:
I guess whoever put it together didn't know, or found them after it was rebuilt and tossed them out. It goes right along with the dizzy being 180 degrees out when I had my local Pontiac guru check the motor out last May. Sheesh... |
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