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#1
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1967 GTO cooling questions
Finally got my car back on the road and have some questions about how the car is cooling. As summer is approaching, I have concerns I will not be able to keep the car cool on the hot days.
Car runs about 170ish around town and about 185ish on the highway when it is about 60-65 degrees out. Highway speeds are 60-65mph / 2400-2700 RPM’s. Just last week I was driving the car home from work and it was 90 degrees out and on the side streets, the car stayed about 185ish and jumped to 205-210 on the highway. Seems like engine speed is playing a big part in cooling. I also notice the temp creeps up on some of the larger hills. Cooling system specs:
So What do you guys think? Are these normal temps? Is the pump turning too fast on the highway?
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Sean 1967 GTO Koerner built 468 with Edelbrock RP’s 315cfm by Butler, Luanti Voodoo HR 20510713, 4l80e, Holley Terminator EFI |
#2
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Although I don't think those numbers are anything to worry about in terms of being too hot, it is odd that your engine is heating up when driving on the freeway.
My '66 has a 400 with iron heads & intake, as well as a Cold Case radiator and an Edelbrock high flow water pump. It'll hold steady at 190F at 55mph (~3k rpm for me) even in 95F humid days. And if I'm hotter than that in the city, driving on the freeway cools it back down. I'm sure others here will have more good insight, but maybe you are leaning out too much?
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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 |
#3
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My 67 ran hot on the hiway with 3.89 to 1 gears and an T400 trans. Went to an OD trans and the temp dropped at least 20 degrees. Sometimes more. Never had a heating problem again.
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#4
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My 67 will run 205 on the Highway on a hot day.....get off the highway and goes down under 200....good enuf. Have the 7 blade fan with hays super clutch....radiator is the original Harrison with a desert cooler core...and fan shroud...stock water pump with the defector plate adjusted real close without hitting the impeller.
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#5
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Rpm's build heat / lean carb jetting will run hot
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#6
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I've never been able to keep a 64-67 GTO cool with electric fans. Came to the conclusion that the fan motors block off too much radiator area that these small radiators can't afford to lose. In every case, when I went back to manual fan, no more overheating. This makes sense since the engine runs warmer on the freeway. Too much radiator being blocked off and can't get air through it.
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Paul Carter Carter Cryogenics www.cartercryo.com 520-409-7236 Koerner Racing Engines You killed it, We build it! 520-294-5758 64 GTO, under re-construction, 412 CID, also under construction. 87 S-10 Pickup, 321,000 miles 99Monte Carlo, 293,000 miles 86 Bronco, 218,000 miles |
#7
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Quote:
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--------------------------- Fool Around, Get Hurt, Don't come Crying to me. |
#8
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Quote:
__________________
--------------------------- Fool Around, Get Hurt, Don't come Crying to me. |
#9
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What size water pump pulley are you using? Smaller diameter pulleys spin the pump faster, equalling more coolant flow. I run 6.5" pulleys out here in AZ.
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"...ridge reamer and ring compressor? Do they have tools like that?" |
#10
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Quote:
and good questions!
__________________
--------------------------- Fool Around, Get Hurt, Don't come Crying to me. |
#11
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Quote:
RPE38L
__________________
Sean 1967 GTO Koerner built 468 with Edelbrock RP’s 315cfm by Butler, Luanti Voodoo HR 20510713, 4l80e, Holley Terminator EFI |
#12
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Interesting thoughts on the mechanical vs electric fan setup. This actually crossed my mind but I thought no way sooo many people run electric fans with excellent results. I still have the factory 7blade fan with a good clutch and repo shroud I could try and see if that helps things
__________________
Sean 1967 GTO Koerner built 468 with Edelbrock RP’s 315cfm by Butler, Luanti Voodoo HR 20510713, 4l80e, Holley Terminator EFI |
#13
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The car is matching #’s ...so I wanted to make the Orig Harrison Rad work....and am happy with the results.
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#14
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Correction I have the 36L. Not the 38L
__________________
Sean 1967 GTO Koerner built 468 with Edelbrock RP’s 315cfm by Butler, Luanti Voodoo HR 20510713, 4l80e, Holley Terminator EFI |
#15
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That model is dual 1". We have since introduced a SD/HO version of the 64-67 GTO radiators for 'super duty' needs. You may have a few other things going on that could help lower temps but if you upgraded to the SD version, your temps would remain steady. No higher than 190.
I know you probably felt the RPE38L would be your last radiator you'd need but many cars are on that bubble. Yours is one of them. Back then CC didn't have a higher capacity option. If you want to consider this option, PM me and we'll figure something out. I think everyone would like to be able for you to come back on this topic and get an update on how the upgrade affected the temps.
__________________
--------------------------- Fool Around, Get Hurt, Don't come Crying to me. |
#16
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Even more of a reason. That is the shorter unit. the 38L was the bigger ac version.
__________________
--------------------------- Fool Around, Get Hurt, Don't come Crying to me. |
#17
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Ok so I removed the electric fans and installed my factory 7 blade mechanical fan, clutch and shroud. My factory shroud was cut to fit an incorrect radiator a long time ago so it isn’t the nicest. I ordered a repo one from Ames that will be here next week. Anyways the car runs MUCH cooler on the freeway. Granted it was much cooler today (between 66-70) but it stayed at 180 on the freeway all the way home and never saw temp creep on the hills.
Now the issue is running about 195 or hotter on side streets. I have a feeling the new shroud will help that but I have my reservations. One question on the mechanical fan and clutch setup: how far should the fan sit inside the shroud? Is a spacer needed between the pulley and clutch to make it closer?
__________________
Sean 1967 GTO Koerner built 468 with Edelbrock RP’s 315cfm by Butler, Luanti Voodoo HR 20510713, 4l80e, Holley Terminator EFI |
#18
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Quote:
__________________
1966 Pontiac GTO (restoration thread) 1998 BMW 328is (track rat) 2023 Subaru Crosstrek Limited (daily) View my photos: Caught in the Wild |
#19
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My fan is not even inside the shroud. And there are gaps all around the shroud to radiator.
Clutch is probably 20 years old but has little use. It feels nice and tight when warm.
__________________
Sean 1967 GTO Koerner built 468 with Edelbrock RP’s 315cfm by Butler, Luanti Voodoo HR 20510713, 4l80e, Holley Terminator EFI |
#20
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If your fan isn't even in the shroud, it's not doing you much good. It won't be able to make any suction to pull air through the core of your radiator, which means it's basically useless at that point. I think you found the reason for getting hot at lower speeds.
__________________
1966 Pontiac GTO (restoration thread) 1998 BMW 328is (track rat) 2023 Subaru Crosstrek Limited (daily) View my photos: Caught in the Wild |
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