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#1
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1968 firebird overheating
Hi All,
My new to me 68 does not like traffic on a hot day. I live in Boston and hit a lot of traffic, almost got stuck in a tunnel. After reading a lot of informative posts here I believe I know how to address the issue. Luckily the owner kept all receipts so I will swap out the 195 thermostat for a robertshaw 180, the cardone waterpump rebuilt in 2000 for a newer pump with the good impeller (probably has the crappy stamped one) along with adjusted divider plate and probably a cold case radiator. My real question is the fan. Right now it has a flex fan on it, not sure of the make but it's 18" 5 blade fan. I would like to put a 19" with a HD fan clutch but I need to figure out 2 things. First is which fan? I have a GM 19" 7 blade 10008888 that I can use, but maybe I should try say a 68 Cadillac flex fan, or some other fan. What works well on the 68 firebird? My second issue is fitting the bigger fan in the shroud. It's a GM 9788883 shroud from around 2001 from Tamraz and the fan fits weird in it. There is well over an inch clearance on the drivers side and top but at the 5 o'clock position on the passenger side there is like 1/4 inch. I tried shifting the shroud to center the fan more but there isn't any adjustment. so I won't be able to fit a bigger fan as is. Were the shroud castings off? are there better ones I can get? are there tricks to moving the shroud around (the top bracket seems to fix it in place though). What fans have you fit into your first gen firebird shroud?
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1966 Lemans convertible 455/5spd 1968 Firebird convertible 400/4spd Need more Pontiacs! Last edited by Tarl; 06-28-2021 at 12:21 PM. Reason: added photo |
#2
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I am thinking the 19" factory 7 blade fan will pull more air than your current fan. Try to keep the fan blade half in/half out of the shroud. Of course try to center the shroud side to side best you can. That setup with a good radiator should work well. Also be sure that the two top cowl plates are installed - those were often removed over the past 50 years.
If you are up for electric, the Ford/Lincoln/Taurus fan fits well on a 1st gen bird and is self contained in its own shroud. It is best to run these gans with a variable speed controller. I use the Lincoln fan with the "big block" cold case radiator and very happy with it. 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 |
The Following User Says Thank You to leeklm For This Useful Post: | ||
#3
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Before you start throwing time, money and parts at it, more info is needed.
What temps are you seeing? Is it heating up in stop and go and cooling down once you get moving? What coolant are you using, and what ratio?
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1965 Pontiac LeMans. M21, 3.73 in a 12 bolt, Kauffman 461. |
#4
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a) I'd go for a 160F. Provides plenty of heat even at 0F.
b) current fan only seems to have 4 blade, I'd want at least 7. c) personally prefer a seven blade metal clutch fan with a close fitting shroud. d) if have a 2 row rad, might consider a 3 or 4 row. e) retarded timing will make a car overheat. f) my Judge has AC and stays around 180F at 90F outside. |
The Following User Says Thank You to padgett For This Useful Post: | ||
#5
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Hi, This was my second time driving around town as its new to me. In stopped traffic after its warmed up on a hot day, it will go to 230+ after 10 minutes, once I got out of traffic I was able find a block to drive around a bunch of times to cool it back down to 190 before I shut it off. I lost about 2 quarts of coolant during that episode, I assume it's 50/50 Glycol, which I replaced it with. driving around without long waits or traffic it's fine will run at 190 to 200 on a hot day, but traffic can get brutal in Boston.
The current shroud isn't really sealed to the radiator, the 5 blade flex fan is in it off center, the radiator is a 4 row copper radiator 23" core. I will pull off the water pump to check the impeller and check clearances before I but a new one.
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1966 Lemans convertible 455/5spd 1968 Firebird convertible 400/4spd Need more Pontiacs! Last edited by Tarl; 06-28-2021 at 04:20 PM. Reason: added detail |
#6
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The tight 5 o'clock business could be due to a bad passenger motor mount.
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'65 Tempest 467 3650# 11.30@120.31 |
#7
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Thanks! will check that, receipts say solid motor mounts though.
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1966 Lemans convertible 455/5spd 1968 Firebird convertible 400/4spd Need more Pontiacs! |
#8
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I agree with the 19" factory 7 blade fan, seems you've done your homework on the rest, good job.
When you change the pump, thermostat, radiator and fan you may not have a overheating issue. As for the shroud not sure whats up, looks like it's pulled back further to the rad on the drivers side. Is that an illusion or does the rad also set a bit closer to the rad support on the drivers side? Frank
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Poncho Huggen, Gear Snatchen, Posi Piro. |
#9
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You have the lower baffle across the valence ?
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#10
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ooh, good thought, I need to check. Thanks!
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1966 Lemans convertible 455/5spd 1968 Firebird convertible 400/4spd Need more Pontiacs! |
#11
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Divider plate.
Adjusting my plate was the most significant improvement I’ve done with the cooling system!
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#12
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Quote:
That shroud is for a 2 core Camaro 327/210 hp. They made 2 widths for the camaros wider was for AC. Pontiac tested and designed fan shrouds in late 50's early 60's. They built them to work on 10.5:1 engines With AC, IN THE desert. Alcohol in fuel, even at 10% , increases engine temps by about 10 degrees on a stock build. This also decreases fuel economy. ( look at any new car window sticker EPA miles per tankful of fuel ) Copper is a MUCH better conductor of heat than Aluminum. Yeah, I said that. It is fact. That said; modern technology in " Routing" fins, and pipe size can make " Some" Aluminum radiators work more efficiently IF it has a Rounded cone style Shroud. Key to Any V8 cooling is a well fitting shroud, well fitting fan, and thickness of the radiator. Ability to transfer heat, aside from known engine / pump mods. Unless your engine is over 10.5 :1 I guarantee you can keep it under 195. If you have a Automatic, and get that trans fluid over 200, you are Cooking your transmission clutches and seals. You can fix this.
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"The Future Belongs to those who are STILL Willing to get their Hands Dirty" .. my Grandfather Last edited by Formulabruce; 07-01-2021 at 02:01 PM. |
#13
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Quote:
And I don't have the lower baffle either, does anyone have pictures with it installed so when it comes from Ames I can do it properly? I have a manual transmission, but I did also notice the radiator was from an automatic and had that cooler section plugged up. Thanks for all the suggestions!
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1966 Lemans convertible 455/5spd 1968 Firebird convertible 400/4spd Need more Pontiacs! |
#14
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I would get some pics of the correct shroud. This last year I got rid of most of my A body stuff and only have F body, and I think the radiators are not as tall as yours.
Pics of original or correct cars can help. I am sure some are out there.
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"The Future Belongs to those who are STILL Willing to get their Hands Dirty" .. my Grandfather |
#15
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Ok,
Checked motor mounts, both new, receipts say solid from butler I think. The engine looks tilted towards the driver side, 14.25 from drivers valve cover, 13.5 from passenger, I am unsure how that could be? New fan will fit I think, but definitely won't be centered. I do have the bottom baffle it turns out. See attached. Pulled off the pump, its a Cardone rebuild and it does have the cast iron impeller, I assume the 68 pumps need the distance from impeller to inner plate done, I am only familiar with the 69+ water pumps. I forgot to check the inner plate distance but I don't know if I can do that on a 68. That being said, think the FlowKooler 68 pump is better than the stock one? I know it's a lot of money but if it helps 5-10 degrees its worth it to me. I am not sure how the 68 compares compared to the stock impeller. Thanks for all your help!
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1966 Lemans convertible 455/5spd 1968 Firebird convertible 400/4spd Need more Pontiacs! |
#16
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Also noticed that some back divider plates have a small cutout around the inner circle, where as some do not. Is there a benefit to one over the other? Mine does not have the cutout.
Thanks!
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1966 Lemans convertible 455/5spd 1968 Firebird convertible 400/4spd Need more Pontiacs! |
#17
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Not to spam, just checked the clearance of the inner plate, seems to range from .175 to .2 inches. The inner plate doesn't seem to have any adjustments, I think I will attempt to bring it down to a consistent .1 and re-install the pump I have instead of a flowkooler and see what happens.
Thanks!
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1966 Lemans convertible 455/5spd 1968 Firebird convertible 400/4spd Need more Pontiacs! |
#18
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The clearance in the second, darker, pic looks terrible, unless its the lighting. The opposite pic looks pretty good.
The inner plate, actually the "divider" , it's function is to take the pump output flow and divide it to each of the banks in the block. The outside plate (or pump housing) should be as close to the pump vane edges as possible. The function of the center hole is to draw coolant from the radiator and the pump vanes pressurize the flow thru the divider and out to the banks. Too much clearance between the vanes and pump housing cause the coolant to circulate around the impeller vanes, thus not going into the block. George
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"...out to my ol'55, I pulled away slowly, feeling so holy, god knows i was feeling alive"....written by Tom Wait from the Eagles' Live From The Forum |
The Following User Says Thank You to george kujanski For This Useful Post: | ||
#19
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Changing to a lower temp thermostat will do nothing...a thermostat only sets the minimum temperature...nothing else.
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Marriage is defined by GOD, not by popular culture! |
#20
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I like to run the Judge at 170-180 and have a 160 thermostat. Is hard to do with a 195.
Will it eliminate overheating, no but it may slow it down a bit. ps "Copper is a MUCH better conductor of heat than Aluminum" yes, the copper cooled chevvy did so well... |
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