[pontiacphil]

I've posted several times in the past about my 67' GTO overheating at idle. It ran hot before my total rebuild this past Winter and it continues to do so after the rebuild. It's a stock 400 bored .30 over, forged flat tops, true 9.48 compression, 670 heads w/ 3-angle valve job, stainless valves, roller tips, Crower #60242, 3:36 gears, rebuilt Turbo 400, Pertronix HEI, Quadrajet that appears to be set correct (not too lean or rich) factory intake, 2 & a half in. exhaust, Ram Air exhaust manifolds with X-pipe, running 91 octane gas, 7 degree advance at 750 RPM idle with total advance at 37 deg. at 3,000 Rpm, Flow Kooler water pump tweaked the way George advised me to, 180 degree Mr. Gasket themostat, Ames shroud. 400 miles on the rebuild running Mobil I 5w-30 with a can of GM EOS and 20 qts. of Mobil I ATF in the tranny.
Before, and after the rebuild, the car gets hot at idle. Will run in the 200 deg. range on the hwy. at 55 mph but as soon as you drop the idle down to under 1,000 RPM it goes to 225 to 230 very quickly. I shut it down at 230 but think it would keep getting hotter if I let it run. I set the idle up to 850 but it didn't help. Had my Harrison 4-core recored and it didn't help any. I ordered a Rodney Red 8 wks. ago and got it last wk. Jerry, the owner, was a very nice guy to work with. Got it installed this morning, used a 50/50 water to antifreeze ratio. used foam to seal the gap around the shroud, went for normal 5 mile cruise route, outside temp. about 90, hoping for the best, and the damn car did exactly what it's been doing! 200 on hwy. and up to 230 in about 3 minutes when you get under 1,000 RPM. I was most surprised that the aluminum Rodney Red didn't lower my temps. any, whatsoever. If I'm setting still in the driveway and boost the RPMs up to around 1,800 it will start dropping the temp. quickly to about 210. My original fan was a 18 in. Flex Fan so I took advice from this site and installed a Hayden #2797 Clutch Thermal Fan and a Hayden #220618 steel fan about 2 months ago and it made no difference with the overheating problem.
So, where do I go from here? I don't know if my temps. drop when you increase the RPM because the fan is drawing more air through the radiator or is it because the water pump is turning faster? How can you tell the difference?
Needless to say I'm very frustrated and don't know what I should do next. I've read every post on this site about overheating and it appears I've done about everything there is to do. If lack of airflow at idle is causing my problem I'm tempted to order a 18 in. Derale #17018 Flex Fan because I've read a lot of good things about it here. Should I ditch the Flow Kooler water pump and try to find a cast impeller NAPA #58-299, 8-bolt water pump, tweak the divider plate the way George K. details, and hope for the best! I've read some positive posts about electric fans but there are some negative posts as well. I really thought, and hoped, that the Rodney Red would solve my overheating problem but it didn't. Sorry for the long post but I would certainly appreciate any help, advice, or suggestions any of you can provide with this matter. Thanks!

[Bill H]

You really have a problem!!
I'm not any kind of expert but I would try advancing the timming a little at a time and see if runs any cooler. I run my 67 about 12* initial with a 400/2801 cam/3:55 gears and a RR. Run runs 185 on the highway all day long. I screwed up and retarded the timming last week and temps went up most rapidly to over 200. Got my timming re-set correctly for my combo and it runs cool again. Just a thought !!!

I have a flex fan and no shroud, had bad luck with fans and shrouds, see my pics on previous thread a couple of post down. Bent fins on alum. rad.
Hope you find a fix soon

[george kujanski]

SOme crazy questions: since you have the 8 bolt pump, do you have the divider plate in there? Any trapped air? Gauge accurate?

How about leaving the cap off the radiator and observing coolant flow at idle, when it opens?

There must ba an answer...Try adding a box fan in front of the car when idling to see if the xtra airflow helps.

Maybe post some pix of the shroud/fan setup?

George

[Bruce Meyer]

I would say your total timing is good but your retarded at idle. I would like to see around 12 degrees timing at idle. You also might want to try hooking vacume advance to direct manifold vacume. That will give you more timing at idle without affecting total. Flex fan will probably do nothing for you. Also you might want to try less antifreeze ratio. Straight water cools the best. You can always add anti freeze when winter comes.

[Blue '66]

The Rodney Red should have made some difference.I would get a new temp gage or a handheld that came check the temp of an object to see if the gage is correct.

[pontiacphil]

Yep, I'm so anal I have now installed 3 different sets of gauges and they all read the same. Plus, you can feel the excessive heat under the hood when it gets in the 220 to 230 range. When I open the cap, and watch the coolant/water mix, it opens and starts a good flow at 185 degrees (it's a 180 thermostat). I still think it's either air flow at low RPM's or the water pump isn't pumping much at low RPM's. The Flow Kooler pump I bought through Summit says it pumps 30% more at low RPM's but I'm not sure that isn't just advertising hype. I truly thought the Rodney Red aluminum radiator would have to help some, just being aluminum, but it didn't make a degree difference over the factory 4-core Harrison. I really thought that would be my solution and was greatly disappointed when it didn't help me. I just don't know what else to do at this point. My dobber is down! I tried both the port and manifold vacuum methods and the overheating remained the same. No difference.

[Matt Meaney]

boy, does this sound familiar. after rebuilding a 455 for my 72 lemans, pretty much the same thing happened. had the radiator bioled and flow check, then installed a new desert cooler rad (4 core), a 160* t-stat, two different clutch fans, one new replacement clutch for the fan, two different afermarket flex fans, an electric pusher fan in front of the rad (made it run hotter), finally put in a factory 5 blade flex fan (non a/c style no clutch) from a 72 350 ventura with a spacer that put the blades half in half out of the shroud. bingo! 175-180* all day long in the summer heat. another idea would be the pulley diameter with the aftermarket pump. it might be spining it too fast or too slow, both arn't good. just some more ideas. hope you get it sorted out soon, so you can start enjoying it.

[DBONES152]

There are 3 things in your original post that are very suspect to an overheating problem.
1. Your initial timing at 7* seems too low. I would advance it to about 12*.
2. Make your idle air/fuel mixture richer.
3. Start using a higher octane fuel. I buy 93 octane and add 110 racing fuel at about a 4 to one mix. There are also several brands of octane boost available although I have never tried them.

[Lemans1]

Another thing to check is your air/fuel ratio. An engine running lean will run hot. I had a car that had a similar problem. After I jetted the carb up and reset the timing, the temps came down almost 15 degrees. Just one more thing to check. Good luck!

[Lemans1]

Another thing to check is your air/fuel ratio. An engine running lean will run hot. I had a car that had a similar problem. After I jetted the carb up and reset the timing, the temps came down almost 15 degrees. Just one more thing to check. Good luck!

[BILTIT]

Anything left in the timing cover holes from painting engine? Ask me how i know!

[topdog1300]

Originally Posted by pontiacphil

I've posted several times in the past about my 67' GTO overheating at idle. It ran hot before my total rebuild this past Winter and it continues to do so after the rebuild. It's a stock 400 bored .30 over, forged flat tops, true 9.48 compression, 670 heads w/ 3-angle valve job, stainless valves, roller tips, Crower #60242, 3:36 gears, rebuilt Turbo 400, Pertronix HEI, Quadrajet that appears to be set correct (not too lean or rich) factory intake, 2 & a half in. exhaust, Ram Air exhaust manifolds with X-pipe, running 91 octane gas, 7 degree advance at 750 RPM idle with total advance at 37 deg. at 3,000 Rpm, Flow Kooler water pump tweaked the way George advised me to, 180 degree Mr. Gasket themostat, Ames shroud. 400 miles on the rebuild running Mobil I 5w-30 with a can of GM EOS and 20 qts. of Mobil I ATF in the tranny.
Before, and after the rebuild, the car gets hot at idle. Will run in the 200 deg. range on the hwy. at 55 mph but as soon as you drop the idle down to under 1,000 RPM it goes to 225 to 230 very quickly. I shut it down at 230 but think it would keep getting hotter if I let it run. I set the idle up to 850 but it didn't help. Had my Harrison 4-core recored and it didn't help any. I ordered a Rodney Red 8 wks. ago and got it last wk. Jerry, the owner, was a very nice guy to work with. Got it installed this morning, used a 50/50 water to antifreeze ratio. used foam to seal the gap around the shroud, went for normal 5 mile cruise route, outside temp. about 90, hoping for the best, and the damn car did exactly what it's been doing! 200 on hwy. and up to 230 in about 3 minutes when you get under 1,000 RPM. I was most surprised that the aluminum Rodney Red didn't lower my temps. any, whatsoever. If I'm setting still in the driveway and boost the RPMs up to around 1,800 it will start dropping the temp. quickly to about 210. My original fan was a 18 in. Flex Fan so I took advice from this site and installed a Hayden #2797 Clutch Thermal Fan and a Hayden #220618 steel fan about 2 months ago and it made no difference with the overheating problem.
So, where do I go from here? I don't know if my temps. drop when you increase the RPM because the fan is drawing more air through the radiator or is it because the water pump is turning faster? How can you tell the difference?
Needless to say I'm very frustrated and don't know what I should do next. I've read every post on this site about overheating and it appears I've done about everything there is to do. If lack of airflow at idle is causing my problem I'm tempted to order a 18 in. Derale #17018 Flex Fan because I've read a lot of good things about it here. Should I ditch the Flow Kooler water pump and try to find a cast impeller NAPA #58-299, 8-bolt water pump, tweak the divider plate the way George K. details, and hope for the best! I've read some positive posts about electric fans but there are some negative posts as well. I really thought, and hoped, that the Rodney Red would solve my overheating problem but it didn't. Sorry for the long post but I would certainly appreciate any help, advice, or suggestions any of you can provide with this matter. Thanks!

I have the same problem and now have ordered a anuminum radiator from Chevellecooling .co they guarantee to run 30 degrees cooler.

[topdog1300]

Originally Posted by pontiacphil

I've posted several times in the past about my 67' GTO overheating at idle. It ran hot before my total rebuild this past Winter and it continues to do so after the rebuild. It's a stock 400 bored .30 over, forged flat tops, true 9.48 compression, 670 heads w/ 3-angle valve job, stainless valves, roller tips, Crower #60242, 3:36 gears, rebuilt Turbo 400, Pertronix HEI, Quadrajet that appears to be set correct (not too lean or rich) factory intake, 2 & a half in. exhaust, Ram Air exhaust manifolds with X-pipe, running 91 octane gas, 7 degree advance at 750 RPM idle with total advance at 37 deg. at 3,000 Rpm, Flow Kooler water pump tweaked the way George advised me to, 180 degree Mr. Gasket themostat, Ames shroud. 400 miles on the rebuild running Mobil I 5w-30 with a can of GM EOS and 20 qts. of Mobil I ATF in the tranny.
Before, and after the rebuild, the car gets hot at idle. Will run in the 200 deg. range on the hwy. at 55 mph but as soon as you drop the idle down to under 1,000 RPM it goes to 225 to 230 very quickly. I shut it down at 230 but think it would keep getting hotter if I let it run. I set the idle up to 850 but it didn't help. Had my Harrison 4-core recored and it didn't help any. I ordered a Rodney Red 8 wks. ago and got it last wk. Jerry, the owner, was a very nice guy to work with. Got it installed this morning, used a 50/50 water to antifreeze ratio. used foam to seal the gap around the shroud, went for normal 5 mile cruise route, outside temp. about 90, hoping for the best, and the damn car did exactly what it's been doing! 200 on hwy. and up to 230 in about 3 minutes when you get under 1,000 RPM. I was most surprised that the aluminum Rodney Red didn't lower my temps. any, whatsoever. If I'm setting still in the driveway and boost the RPMs up to around 1,800 it will start dropping the temp. quickly to about 210. My original fan was a 18 in. Flex Fan so I took advice from this site and installed a Hayden #2797 Clutch Thermal Fan and a Hayden #220618 steel fan about 2 months ago and it made no difference with the overheating problem.
So, where do I go from here? I don't know if my temps. drop when you increase the RPM because the fan is drawing more air through the radiator or is it because the water pump is turning faster? How can you tell the difference?
Needless to say I'm very frustrated and don't know what I should do next. I've read every post on this site about overheating and it appears I've done about everything there is to do. If lack of airflow at idle is causing my problem I'm tempted to order a 18 in. Derale #17018 Flex Fan because I've read a lot of good things about it here. Should I ditch the Flow Kooler water pump and try to find a cast impeller NAPA #58-299, 8-bolt water pump, tweak the divider plate the way George K. details, and hope for the best! I've read some positive posts about electric fans but there are some negative posts as well. I really thought, and hoped, that the Rodney Red would solve my overheating problem but it didn't. Sorry for the long post but I would certainly appreciate any help, advice, or suggestions any of you can provide with this matter. Thanks!

I have the same problem and now have ordered a anuminum radiator from Chevellecooling .co they guarantee to run 30 degrees cooler.

[topdog1300]

Originally Posted by pontiacphil

I've posted several times in the past about my 67' GTO overheating at idle. It ran hot before my total rebuild this past Winter and it continues to do so after the rebuild. It's a stock 400 bored .30 over, forged flat tops, true 9.48 compression, 670 heads w/ 3-angle valve job, stainless valves, roller tips, Crower #60242, 3:36 gears, rebuilt Turbo 400, Pertronix HEI, Quadrajet that appears to be set correct (not too lean or rich) factory intake, 2 & a half in. exhaust, Ram Air exhaust manifolds with X-pipe, running 91 octane gas, 7 degree advance at 750 RPM idle with total advance at 37 deg. at 3,000 Rpm, Flow Kooler water pump tweaked the way George advised me to, 180 degree Mr. Gasket themostat, Ames shroud. 400 miles on the rebuild running Mobil I 5w-30 with a can of GM EOS and 20 qts. of Mobil I ATF in the tranny.
Before, and after the rebuild, the car gets hot at idle. Will run in the 200 deg. range on the hwy. at 55 mph but as soon as you drop the idle down to under 1,000 RPM it goes to 225 to 230 very quickly. I shut it down at 230 but think it would keep getting hotter if I let it run. I set the idle up to 850 but it didn't help. Had my Harrison 4-core recored and it didn't help any. I ordered a Rodney Red 8 wks. ago and got it last wk. Jerry, the owner, was a very nice guy to work with. Got it installed this morning, used a 50/50 water to antifreeze ratio. used foam to seal the gap around the shroud, went for normal 5 mile cruise route, outside temp. about 90, hoping for the best, and the damn car did exactly what it's been doing! 200 on hwy. and up to 230 in about 3 minutes when you get under 1,000 RPM. I was most surprised that the aluminum Rodney Red didn't lower my temps. any, whatsoever. If I'm setting still in the driveway and boost the RPMs up to around 1,800 it will start dropping the temp. quickly to about 210. My original fan was a 18 in. Flex Fan so I took advice from this site and installed a Hayden #2797 Clutch Thermal Fan and a Hayden #220618 steel fan about 2 months ago and it made no difference with the overheating problem.
So, where do I go from here? I don't know if my temps. drop when you increase the RPM because the fan is drawing more air through the radiator or is it because the water pump is turning faster? How can you tell the difference?
Needless to say I'm very frustrated and don't know what I should do next. I've read every post on this site about overheating and it appears I've done about everything there is to do. If lack of airflow at idle is causing my problem I'm tempted to order a 18 in. Derale #17018 Flex Fan because I've read a lot of good things about it here. Should I ditch the Flow Kooler water pump and try to find a cast impeller NAPA #58-299, 8-bolt water pump, tweak the divider plate the way George K. details, and hope for the best! I've read some positive posts about electric fans but there are some negative posts as well. I really thought, and hoped, that the Rodney Red would solve my overheating problem but it didn't. Sorry for the long post but I would certainly appreciate any help, advice, or suggestions any of you can provide with this matter. Thanks!

I have the same problem and now have ordered a anuminum radiator from Chevellecooling .co they guarantee to run 30 degrees cooler.

[topdog1300]

Originally Posted by pontiacphil

I've posted several times in the past about my 67' GTO overheating at idle. It ran hot before my total rebuild this past Winter and it continues to do so after the rebuild. It's a stock 400 bored .30 over, forged flat tops, true 9.48 compression, 670 heads w/ 3-angle valve job, stainless valves, roller tips, Crower #60242, 3:36 gears, rebuilt Turbo 400, Pertronix HEI, Quadrajet that appears to be set correct (not too lean or rich) factory intake, 2 & a half in. exhaust, Ram Air exhaust manifolds with X-pipe, running 91 octane gas, 7 degree advance at 750 RPM idle with total advance at 37 deg. at 3,000 Rpm, Flow Kooler water pump tweaked the way George advised me to, 180 degree Mr. Gasket themostat, Ames shroud. 400 miles on the rebuild running Mobil I 5w-30 with a can of GM EOS and 20 qts. of Mobil I ATF in the tranny.
Before, and after the rebuild, the car gets hot at idle. Will run in the 200 deg. range on the hwy. at 55 mph but as soon as you drop the idle down to under 1,000 RPM it goes to 225 to 230 very quickly. I shut it down at 230 but think it would keep getting hotter if I let it run. I set the idle up to 850 but it didn't help. Had my Harrison 4-core recored and it didn't help any. I ordered a Rodney Red 8 wks. ago and got it last wk. Jerry, the owner, was a very nice guy to work with. Got it installed this morning, used a 50/50 water to antifreeze ratio. used foam to seal the gap around the shroud, went for normal 5 mile cruise route, outside temp. about 90, hoping for the best, and the damn car did exactly what it's been doing! 200 on hwy. and up to 230 in about 3 minutes when you get under 1,000 RPM. I was most surprised that the aluminum Rodney Red didn't lower my temps. any, whatsoever. If I'm setting still in the driveway and boost the RPMs up to around 1,800 it will start dropping the temp. quickly to about 210. My original fan was a 18 in. Flex Fan so I took advice from this site and installed a Hayden #2797 Clutch Thermal Fan and a Hayden #220618 steel fan about 2 months ago and it made no difference with the overheating problem.
So, where do I go from here? I don't know if my temps. drop when you increase the RPM because the fan is drawing more air through the radiator or is it because the water pump is turning faster? How can you tell the difference?
Needless to say I'm very frustrated and don't know what I should do next. I've read every post on this site about overheating and it appears I've done about everything there is to do. If lack of airflow at idle is causing my problem I'm tempted to order a 18 in. Derale #17018 Flex Fan because I've read a lot of good things about it here. Should I ditch the Flow Kooler water pump and try to find a cast impeller NAPA #58-299, 8-bolt water pump, tweak the divider plate the way George K. details, and hope for the best! I've read some positive posts about electric fans but there are some negative posts as well. I really thought, and hoped, that the Rodney Red would solve my overheating problem but it didn't. Sorry for the long post but I would certainly appreciate any help, advice, or suggestions any of you can provide with this matter. Thanks!

I have the same problem and now have ordered a anuminum radiator from Chevellecooling .co they guarantee to run 30 degrees cooler.

[bobbyj1]

I have been battling the idle problem since I got my car 3 years ago. Since my engine rebuild this past winter I have been expirementing with fan/shroud setups trying to find a combination that will solve this. I have a 67 GTO no/ac, with a Rodney Red Radiator. I have run without a shroud, with one, thermal fan clutch, non-thermal fan clutch. Yesterday I went with Rugrat's setup. I put a Flex-a-lite 18" 7 blade felx fan with a 2" spacer in and I was able to let my car idle in the garage for 15 minutes and the temp stayed around 190. Something I would never have been able to do before. I think you have to just keep trying different things until you hit on the one that works.

Bob

[ctgross]

One other thing that might? help is drill 4 or 5 3/16" holes around the flat portion of a thermostat. I got the tip from here about a year ago. It dropped my average temp. about 15 deg. Cheap fix if it helps.

[70GS455]

Have you tried one of the large-diameter high-flow thermostats like Stewart makes?

[69ra3ta]

Try this link. This detail is often overlooked.

http://www.wallaceracing.com/water-pump-mods.php

Doug

[george kujanski]

With a Rodney in there, it should do the job for you IF you can get the heat out of the engine (coolant flow) and dump it to the air (air flow thru the rad).

Not much more to it than that. Bobbyj1 had success by changing his fan setup. Good clue there.

George