# Overheating issue



## hot 65 (11 mo ago)

Hi, new to the site. My 65 Gto is overheating. Complete rebuild on the 389, have gone from high flow water pump back to correct one 160 stat. aluminum 3 core radiator now to a 4 core. 17 inch mechanical fan with shroud. Looked into converting to a 69 style timing housing and pump. Some people say it will Definity help and some say it doesn't. Any thoughts on the issue? Also after acquiring a tri power set up I am told it won't work with the 69 style timing housing. Any suggestions or do i stay with the 4 barrel set up.
Thanks for any advice and help.


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## Jared (Apr 19, 2013)

So a couple things to check is the shroud to fan clearance and the timing. If someone set the timing retarded (opposite of advanced), the engine will run hot. How is the oil pressure. My old engine ran hot, and had lower oil pressure. The heat was due to friction (friction is bad). Is it actually running hot? Bad gauge or sender?


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## BLK69JUDGE (Jun 10, 2010)

hello
did you clearance the shield/deflector behind the water pump
to the impeller ?
timing as Jared mentioned,,
69 timing covers still have the dimple for tripower 
at least the 20+ one I have had did,, including 70 beacause they are the same part number
changing covers requires 
69-70 water pump pulley
69-70 crank pulley
67-70 power steering pump n pulley n ALL brackets
new belts

youlle get some great advice here 

what spacer depth are you running fan should be 1/2 in half out

automatic tranny stall converter going thru the radiator ??

does it get hot at an idle and cool going down the road ??

whats your outside temp ?

have you a mechanical gauge?/ aftermarket on it now ?

thats all I got for now need to get to the shop b4 traffic picks up

Scott


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## Baaad65 (Aug 29, 2019)

How new is the rebuild, a tight engine is going to run hotter at first, drill a few 1/8" holes in the stat, and I've heard and read a large two core radiator is better than a small tube four core. Pulley size right on the pump? What's overheating mean, if you're at 200 or lower that's not horrible depending on the circumstances. Just because you have a 160 stat it's not going to run there besides that's too cold.


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## hot 65 (11 mo ago)

BLK69JUDGE said:


> hello
> did you clearance the shield/deflector behind the water pump
> to the impeller ?
> timing as Jared mentioned,,
> ...


Thanks Scott. Yes to most of your questions, I am aware of the pully changes that would be needed. Ames says the 69 timing cover won't work with the tri power and so does Butler performance The motor is tight less than200 miles professional build , 4 speed m-21 tranny . Runs cool at idle. we are in a warm summer to cold winter climate. the 4 core has large tubes. Most likely a stupid question but how to clearance the devider plates. I know they have to be in a certain way. It will get 220 + on hot days on the road. I shut it down at that point. Have a new gauge to install. Thanks for the input


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## hot 65 (11 mo ago)

Baaad65 said:


> How new is the rebuild, a tight engine is going to run hotter at first, drill a few 1/8" holes in the stat, and I've heard and read a large two core radiator is better than a small tube four core. Pulley size right on the pump? What's overheating mean, if you're at 200 or lower that's not horrible depending on the circumstances. Just because you have a 160 stat it's not going to run there besides that's too cold.





Baaad65 said:


> How new is the rebuild, a tight engine is going to run hotter at first, drill a few 1/8" holes in the stat, and I've heard and read a large two core radiator is better than a small tube four core. Pulley size right on the pump? What's overheating mean, if you're at 200 or lower that's not horrible depending on the circumstances. Just because you have a 160 stat it's not going to run there besides that's too cold.


Hi Jared , thanks for your input. The motor is still fresh about 200 mi. I expect to run hot but it will go 220 + if I don't shut it down. I haven't tried drilling holes yet but have heard of it helping. the 4 core has large tubes, correct pully . Thanks for your input and open to any advice. I am not a real savy mechanic just enough to get me by.


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## Baaad65 (Aug 29, 2019)

I bet it could be the tight motor, also what are you using for coolant? Antifreeze is a terrible heat transfer, I'm going to flush mine after a heater core change and use distilled water only with water wetter, if you don't leave the car in freezing temperatures you can do that but you need a rust inhibitor that's in the water wetter like products. And you said the timing is correct? Do you have a high compression motor?


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## PontiacJim (Dec 29, 2012)

hot 65 said:


> Hi Jared , thanks for your input. The motor is still fresh about 200 mi. I expect to run hot but it will go 220 + if I don't shut it down. I haven't tried drilling holes yet but have heard of it helping. the 4 core has large tubes, correct pully . Thanks for your input and open to any advice. I am not a real savy mechanic just enough to get me by.


Get a hand held laser temp gun from the local auto parts store - not too expensive. Then verify your engine temps at the top of the radiator, bottom of radiator, right/left head, thermostat housing/water crossover. Don't trust the gauge/sending unit. Where is your temp sending unit - in the water crossover, and not the side of the head?

Do the temp check first before doing anything else. Then get back to us.

Make sure you have the correct V-belts that fit the pulleys and grip the sides of the pulleys. Some "it says they fit" belts are metric and are too small and rather than pull the pulley off of the side v-grooves, they sit deep on the center spool of the pulley and look OK, but actually slip on the spool and won't cool the engine. I like the Dayco cogged top belts as they seem to fit like factory.


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## BLK69JUDGE (Jun 10, 2010)

wierd I had a 66 tripower on a 69 wt 400 w 48 heads years ago blew that up and bolted it on a 71 455

something else I thought of I had an issue with was my lower hose would collapse... on a 65 GTO I had bought a new hose with the coil spring
inside and it seemed to help


clearancing pointiac water pump - Google Search


Scott t


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## hot 65 (11 mo ago)

PontiacJim said:


> Get a hand held laser temp gun from the local auto parts store - not too expensive. Then verify your engine temps at the top of the radiator, bottom of radiator, right/left head, thermostat housing/water crossover. Don't trust the gauge/sending unit. Where is your temp sending unit - in the water crossover, and not the side of the head?
> 
> Do the temp check first before doing anything else. Then get back to us.
> 
> Make sure you have the correct V-belts that fit the pulleys and grip the sides of the pulleys. Some "it says they fit" belts are metric and are too small and rather than pull the pulley off of the side v-grooves, they sit deep on the center spool of the pulley and look OK, but actually slip on the spool and won't cool the engine. I like the Dayco cogged top belts as they seem to fit like factory.


Thanks for the advise, I do have a laser gun and have used it


Baaad65 said:


> I bet it could be the tight motor, also what are you using for coolant? Antifreeze is a terrible heat transfer, I'm going to flush mine after a heater core change and use distilled water only with water wetter, if you don't leave the car in freezing temperatures you can do that but you need a rust inhibitor that's in the water wetter like products. And you said the timing is correct? Do you have a high compression motor?





Baaad65 said:


> I bet it could be the tight motor, also what are you using for coolant? Antifreeze is a terrible heat transfer, I'm going to flush mine after a heater core change and use distilled water only with water wetter, if you don't leave the car in freezing temperatures you can do that but you need a rust inhibitor that's in the water wetter like products. And you said the timing is correct? Do you have a high compression motor?


Thanks for the reply. I am running a 50 / 50 mixture now we get down tot he single digets here in the winter sometimes. No it's not a high compression motor


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## BearGFR (Aug 25, 2008)

Have you verified your divider plate clearance?


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## PontiacJim (Dec 29, 2012)

*hot 65* - "Thanks for the advise, I do have a laser gun and have used it"

*PJ* - And those number are????

Next up, low compression engine? How low? How did you drop compression? Did you check your squish/quench numbers? Very important on a closed chamber head - if yours are still original. If you have a large squish/quench measurement, you can experience a hot running engine/detonation.

Give us your timing specs - with vacuum advance disconnected. Initial timing at the balancer, Total timing and at what RPM is it reached. Then re-connect the vacuum advance and let us know how much the Initial timing at the balancer jumps up.

Are you using a camshaft with stock 1965 specs or an aftermarket grind?

What rear gear ratio do you have and is the overheating at certain speeds - like highway speeds of 60-70 MPH?


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## hot 65 (11 mo ago)

PontiacJim said:


> *hot 65* - "Thanks for the advise, I do have a laser gun and have used it"
> 
> *PJ* - And those number are????
> 
> ...


Sorry I don't have the numbers for sure I think compression was 9 1 /2 to 10, comp cam 280. Rear end is 178 psi., 4 speed trans. stock heads roller rockers. Hei distributor. holly hi rise alum. manifold with edlebrock 650 carb and and stock ram air exaust manifolds. I am sorry I don't have exact info. it has been a 20 + year project and a couple moves. The builder was a professional that was a good friend but unfortunately he died on me and at my age memory isn't the greatest. I will start with clearance on the divider plates. The timing I need some help on there are no timing marks so timed by ear. 
2 questions I have, 1 is probably showing my ignorance should I have a straight 7 blade fan or a clutch fan? When I got the car it was a straight fan. 2nd question when I take the water pump apart to clearance should I go back to the stock pump or use the high flowcooler pump that I installed at first.
Thanks for all the help agian.


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## BearGFR (Aug 25, 2008)

If you're not positive where the timing is at, that's probably the single most important thing.


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## hot 65 (11 mo ago)

BearGFR said:


> If you're not positive where the timing is at, that's probably the single most important thing.


Thanks I need to figure out how to correct that. Going to need more help with that. Open to suggestions.
Thanks for the reply.


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## Baaad65 (Aug 29, 2019)

"Rear end is a 178 psi " ??? Are you running lean? How do the plugs look and was it running hot before the rebuild?


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## hot 65 (11 mo ago)

Baaad65 said:


> "Rear end is a 178 psi " ??? Are you running lean? How do the plugs look and was it running hot before the rebuild?


I think the gears are 178s posi. No it no running lean. When i got the car 25 years ago the moor was pretty much toast


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## hot 65 (11 mo ago)

hot 65 said:


> I think the gears are 178s posi. No it no running lean. When i got the car 25 years ago the moor was pretty much toast


When I had it apart I counted the rear end gears but as I said at my age the memory isn't a strong point. I do remember it was in the mid 170s


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## Baaad65 (Aug 29, 2019)

Never heard of a gear that low.


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## PontiacJim (Dec 29, 2012)

hot 65 said:


> Thanks I need to figure out how to correct that. Going to need more help with that. Open to suggestions.
> Thanks for the reply.


1.) Don't work on the water pump just yet. But, do you recall which divider you used? You want the one without the notch - enclosed pictures of the two. I pulled this off the Butler website and here is what they say:

"Some 1964-65 timing covers had a divider plate already cast into the cover. These divider plates are sold in sets and the bottom plate will not be used in this case.

The 2pc plates were made in 2 versions. The 64-65 had a notch and later models the notch was removed. This notch could have been to keep water from getting trapped behind the plate but in all of our testing it seemed that the single hole directed more water into the engine and may have been the reason it was removed in the later models. Early 8 bolt designs are notorious for cooling issues. The 2pc plate we sell *without the notch *works in all 1964-68 models regardless of timing cover.

2.) You want to tackle your timing first. Your timing settings could be your issue with the hot running engine. Your timing cover should have a pointer, no scale. Enclosed picture of 1964-65 Timing Cover. The harmonic balancer should have 2 lines on it. The lower line is top dead center, 0 degrees. The upper line is 6* BTDC. that's where you want the pointer with distributor vaccum line disconnected and plugged.

3.) If you have a "big cap" original type HEI, it will not clear the tri-power end carb. The trip-power waterneck is in the front of the intake versus being on top in the 2 Bbl/4Bbl intakes, this is why you need a timing cover which will have a recess in it to match the water neck. Most timing covers will have the recess, so you need this to use the tri-power. 

4.) The M-21 transmission is a close ratio. M-20 is the wide ratio and most common. Is your trans the close ratio M-21?

5.) There is no "1.78" gear ratio. Did you mean "2.78" ? Believe the lowest gear you could get on a GTO was 3.08 and that would have been with an M-20 wide ratio trans. Was your car originally an automatic?

6.) The 7-blade fan should be correct. The clutch type fan was used with AC or with the heavy duty radiator. You should have a fan shroud as well.


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## Jared (Apr 19, 2013)

Which timing marks are missing, the damper or on the cover? I've had two different timing covers on mine, both with the 11 bolt pump. The old one had a tab that was held on by 2 of the timing cover bolts, the new one has the marks cast into the cover. I won't pretend to be an expert or know if the older covers are different, but someone else on here may know. I agree with what others are saying, I think you need to make sure the timing is correct before you start taking anything else apart. If you're missing the timing marks, you need to source the correct one for the timing cover you have and start there.

Good luck with this and keep asking questions. You are not the first person on here to run into trouble and need help. That was me last fall. The guys on here will help you the best we can.


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## hot 65 (11 mo ago)

Jared said:


> Which timing marks are missing, the damper or on the cover? I've had two different timing covers on mine, both with the 11 bolt pump. The old one had a tab that was held on by 2 of the timing cover bolts, the new one has the marks cast into the cover. I won't pretend to be an expert or know if the older covers are different, but someone else on here may know. I agree with what others are saying, I think you need to make sure the timing is correct before you start taking anything else apart. If you're missing the timing marks, you need to source the correct one for the timing cover you have and start there.
> 
> Good luck with this and keep asking questions. You are not the first person on here to run into trouble and need help. That was me last fall. The guys on here will help you the best we can.


Yea I am trying to figure out where to start . the timing cover is a 8 bolt style with the point for the timing. There is no mark on the balancer, thats the problem. So I see 2 options 1 pull the valve cover and try to get number 1 at TDC then try and mark the balancer or 2 pull it and install a new one with marks and go from there.
Thanks for your input


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## hot 65 (11 mo ago)

PontiacJim said:


> 1.) Don't work on the water pump just yet. But, do you recall which divider you used? You want the one without the notch - enclosed pictures of the two. I pulled this off the Butler website and here is what they say:
> 
> "Some 1964-65 timing covers had a divider plate already cast into the cover. These divider plates are sold in sets and the bottom plate will not be used in this case.
> 
> ...


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## Baaad65 (Aug 29, 2019)

hot 65 said:


> Yea I am trying to figure out where to start . the timing cover is a 8 bolt style with the point for the timing. There is no mark on the balancer, thats the problem. So I see 2 options 1 pull the valve cover and try to get number 1 at TDC then try and mark the balancer or 2 pull it and install a new one with marks and go from there.
> Thanks for your input


No groove in the balancer either?


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## BearGFR (Aug 25, 2008)

hot 65 said:


> Yea I am trying to figure out where to start . the timing cover is a 8 bolt style with the point for the timing. There is no mark on the balancer, thats the problem. So I see 2 options 1 pull the valve cover and try to get number 1 at TDC then try and mark the balancer or 2 pull it and install a new one with marks and go from there.
> Thanks for your input


Just because a balancer is new, you can't assume it's marked correctly. The balancer I was running on my engine several years ago, which was SFI rated and not cheap - had markings that were off by 6 degrees. I never would have known it had I not checked it. The one I have now, a Romac from Butler - also SFI rated, has accurate markings but I still verified it to make sure.

I'd never replace a balancer, or use an existing one, until I'd verified the markings on it. There's a process that you can use to do so using a piston stop inserted into the spark plug hole, but you have to be very careful and make SURE you remove the rocker arms on #1 cylinder beforehand, otherwise you run the risk of bending a valve when it opens and contacts the stop. Trying to 'eyeball' where TDC is just by removing the rocker cover will never be accurate enough. Near TDC when the rod end is moving mostly "sideways" and the up/down motion of the piston is so gradual, it's just not possible to locate TDC by eye. Even with the head removed - you can't be precise enough.

It's easier to do with the head off and using a dial indicator, but can be done without removing the head as long as you're very careful.

Here's how: (edited to fix a sequencing mistake I missed originally - thanks BLK69JUDGE)

Buy a piston stop that can be inserted into a spark plug hole, or MAKE one by knocking the center porcelain out of an old spark plug, cutting threads into the metal body, and threading a length of all-thread rod into it. Use the fattest rod that'll fit thought the old plug body. You want something that won't bend/deflect easily. Put a nut on the 'outside' side of the rod that you can use for a jam nut.
Remove the driver side rocker cover
Disconnect the battery - you want to make it impossible for the starter to operate
Remove #1 spark plug (or all of them if you choose, to make it easier to turn the engine over by hand)
Use a socket and a breaker bar to turn the engine over by hand
Watch for the intake valve to start CLOSING.
Continue turning until your existing balancer marks show that you're approximately 30 degrees "or so" BEFORE TDC -- the mark/groove on the balancer is "an inch or so" before the TDC mark on the timing cover. The exact distance isn't important. What you're trying to do is find a spot where you know the piston hasn't yet reached TDC, but it's close enough for you to reach it when you thread the rod down.
*>>>Remove both rocker arms from #1 cylinder. Do not skip this step, otherwise you can bend valves.<<<*
NOW insert your piston stop with the "engine side" of the rod all the way to the top.
GENTLY screw in the all-thread/stop rod until you feel it touch the top of the piston, and you can't easily thread it in in farther.
Run the jam nut down on the rod and tighten it slightly to make sure it doesn't move.
Using a marker, piece of tape, something -- make a mark on the balancer that lines up exactly with the TDC mark on the timing cover. Be as precise as you can.
Now, using the breaker bar, turn the engine BACKWARDS around the other direction - counter clockwise - slowly and gently. You're trying to find the spot where the piston again touches the stop and you can't turn the crankshaft any farther in that direction. Don't "he man" this! You can bend the rod on the stop which will result in a false reading, and you can also put a dent in the piston crown.
When you find the spot going 'the other direction' where the piston hits the stop, make another mark on the balancer at that point that lines up with TDC on the timing cover.
True TDC on the balancer is exactly half-way between the two marks you made.
Make a permanent mark at that point - that's where TDC is. File in a shallow groove, put on a timing tape (make sure you get one that's right for your balancer diameter), use paint that won't fade or come off --- something.
Remove the rod, the stop, reinstall the rockers (making sure to use whatever adjustment procedure is right for your setup), rocker cover, plug, wire, reconnect your battery, etc....

Now when you set timing using that mark, you'll know it's correct. Personally I prefer to use a 'dial back' timing light.

Bear


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## vettvet (Oct 17, 2013)

hot 65 said:


> Hi, new to the site. My 65 Gto is overheating. Complete rebuild on the 389, have gone from high flow water pump back to correct one 160 stat. aluminum 3 core radiator now to a 4 core. 17 inch mechanical fan with shroud. Looked into converting to a 69 style timing housing and pump. Some people say it will Definity help and some say it doesn't. Any thoughts on the issue? Also after acquiring a tri power set up I am told it won't work with the 69 style timing housing. Any suggestions or do i stay with the 4 barrel set up.
> Thanks for any advice and help.


Are you still using the stock oil filter canister?


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## 1964oldgoat (Aug 7, 2020)

Baaad65 said:


> How new is the rebuild, a tight engine is going to run hotter at first, drill a few 1/8" holes in the stat, and I've heard and read a large two core radiator is better than a small tube four core. Pulley size right on the pump? What's overheating mean, if you're at 200 or lower that's not horrible depending on the circumstances. Just because you have a 160 stat it's not going to run there besides that's too cold.


I’m running a rebuilt 389 with tripower and it gets up to 200-210 sometimes (usually in traffic or stopped in Florida heat); usually hangs around 190.


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## Rockinindian (Aug 5, 2021)

hot 65 said:


> Hi, new to the site. My 65 Gto is overheating. Complete rebuild on the 389, have gone from high flow water pump back to correct one 160 stat. aluminum 3 core radiator now to a 4 core. 17 inch mechanical fan with shroud. Looked into converting to a 69 style timing housing and pump. Some people say it will Definity help and some say it doesn't. Any thoughts on the issue? Also after acquiring a tri power set up I am told it won't work with the 69 style timing housing. Any suggestions or do i stay with the 4 barrel set up.
> Thanks for any advice and help.


Fan clutch NFG can be the culprit . They can appear to be spinning but the enternal thermostat that controls the hydrolic can bleed the pressure to the fins internally. If you have any performance parts causing more heat go with extreme duty.


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## Montreux (Mar 8, 2009)

If your car runs cool at idle and gets hot going down the road, either you have a radiator that is too small or you have an airflow problem. Aluminum is not a magic bullet.

Airflow is the likely culprit. Is the radiator properly mounted to the radiator support so that air is forced THROUGH the radiator and not around it? A/C cars had a set of baffles to seal the radiator to the support.

Have you added A/C? If the condenser is mounted too close to the radiator it can restrict the airflow.

At road speed, the engine fan is (almost) not needed, the water pump is turning faster, and the timing should be somewhat advanced. This eliminates most of the factors that cause overheating at idle.


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## Montreux (Mar 8, 2009)

Timing could be your problem. If you’re running HEI, we can assume the timing curve is NOT stock. You need to check your timing at speed; you’re looking for 32-34 degrees when the mechanical advance is “all in”—no longer advancing.
Most factory advance curves had 5 or 6 degrees initial advance, 14 or 15 degrees mechanical advance in the distributor (28-30 at the crank), for a total of around 34 degrees. Mechanical advance might not be “all in” until 4000 RPM or higher.

Ram Air/HO cars, most HEI, and “recurved” distributors have a faster, steeper advance curve. They may only have 10 degrees of advance in the distributor (20 at the crank) all in by 3500 RPM, and require 12-15 degrees initial advance to achieve 34-36 degree total timing.

So—
You need to check TOTAL timing, and take what you get for initial timing.

Total timing can be checked using timing tape or a dial-back timing light. Vacuum advance should be disconnected and plugged while checking the timing.

And, yes, you want to run vacuum advance on the street. This will add as much as 20 degrees (at the crank) advance under light-load cruising conditions, helping to avoid overheating and improving gas mileage.


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## hot 65 (11 mo ago)

1964oldgoat said:


> I’m running a rebuilt 389 with tripower and it gets up to 200-210 sometimes (usually in traffic or stopped in Florida heat); usually hangs around 190.


Funny thats my LIc. plate Old Goat. Are you running the original 8 bolt water pump or did you swithch over to the 11 bolt?


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## hot 65 (11 mo ago)

Montreux said:


> Timing could be your problem. If you’re running HEI, we can assume the timing curve is NOT stock. You need to check your timing at speed; you’re looking for 32-34 degrees when the mechanical advance is “all in”—no longer advancing.
> Most factory advance curves had 5 or 6 degrees initial advance, 14 or 15 degrees mechanical advance in the distributor (28-30 at the crank), for a total of around 34 degrees. Mechanical advance might not be “all in” until 4000 RPM or higher.
> 
> Ram Air/HO cars, most HEI, and “recurved” distributors have a faster, steeper advance curve. They may only have 10 degrees of advance in the distributor (20 at the crank) all in by 3500 RPM, and require 12-15 degrees initial advance to achieve 34-36 degree total timing.
> ...


Thank you for the advice I wasn't aware of that much difference with the HEI


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## hot 65 (11 mo ago)

Montreux said:


> If your car runs cool at idle and gets hot going down the road, either you have a radiator that is too small or you have an airflow problem. Aluminum is not a magic bullet.
> 
> Airflow is the likely culprit. Is the radiator properly mounted to the radiator support so that air is forced THROUGH the radiator and not around it? A/C cars had a set of baffles to seal the radiator to the support.
> 
> ...


The radiator is mounted in the original position. After market AC but It's never been hooked up, never a belt on it. I been considering just removing the AC all together due to the problem. AS of now the condenser is not restricting air flow.


vettvet said:


> Are you still using the stock oil filter canister?


Yes it is a stock filter. What would a stock oil filter have to do with over heating? Sorry if it's a stupid question I am not a mechanic by any means.


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## hot 65 (11 mo ago)

Rockinindian said:


> Fan clutch NFG can be the culprit . They can appear to be spinning but the enternal thermostat that controls the hydrolic can bleed the pressure to the fins internally. If you have any performance parts causing more heat go with extreme duty.


No clutch , just a straight fan 17 inch


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## hot 65 (11 mo ago)

Montreux said:


> If your car runs cool at idle and gets hot going down the road, either you have a radiator that is too small or you have an airflow problem. Aluminum is not a magic bullet.
> 
> Airflow is the likely culprit. Is the radiator properly mounted to the radiator support so that air is forced THROUGH the radiator and not around it? A/C cars had a set of baffles to seal the radiator to the support.
> 
> ...


running a 4 core Champion radiator.


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## 1964oldgoat (Aug 7, 2020)

hot 65 said:


> Funny thats my LIc. plate Old Goat. Are you running the original 8 bolt water pump or did you swithch over to the 11 bolt?


Running the original - but with all new parts - water pump. And I have an electric fan on an aftermarket aluminum radiator with no shroud. I suspect the lack of a shroud is my problem. Thoughts?


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## kevin1727 (Aug 4, 2021)

My builder has restored many Pontiacs and installed a lot of 400+ size engines. In addition to the bigger radiator, he swears this is the answer to over heating. 








FlowKooler Hi Flow Water Pumps


FlowKooler pumps patented impeller design helps stop engines from overheating and reduces engine temperature up to 30 degrees by doubling the flow of coolant and building system pressure.




flowkoolerwaterpumps.com


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## 1964oldgoat (Aug 7, 2020)

Wow - these look great! Are you running one? Just curious. And do you think hitting 210 in traffic is considered overheating?


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## Baaad65 (Aug 29, 2019)

210° in traffic isn't too bad but what's the outside temperature? I have the same problem in traffic when it's 80° or hotter and I don't have much of a shroud either so I have the flow cooler pump, drilled 160 stat, 16" 2600cfm puller fan then I added two 13" pusher fans on a separate switch. Then I'm going to run distilled water with water wetter this summer....and my timing and carb are finally adjusted correctly.


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## Jared (Apr 19, 2013)

1964oldgoat said:


> Running the original - but with all new parts - water pump. And I have an electric fan on an aftermarket aluminum radiator with no shroud. I suspect the lack of a shroud is my problem. Thoughts?


So, no shroud? Just the electric fan attached to the radiator directly (zip ties or something similar?)? That would be the first area I'd look at.


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## Jared (Apr 19, 2013)

kevin1727 said:


> My builder has restored many Pontiacs and installed a lot of 400+ size engines. In addition to the bigger radiator, he swears this is the answer to over heating.
> 
> 
> 
> ...


I'm running one in mine. Engine didn't go back in the car until late September so no dog days of summer driving yet. That being said, the combo of that water pump (11 bolt), a Cold Case radiator, and a 165 degree thermostat, my engine never got hotter than 170 on days warmer than 70. I'm running the factory fan clutch and shroud.


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## kevin1727 (Aug 4, 2021)

1964oldgoat said:


> Wow - these look great! Are you running one? Just curious. And do you think hitting 210 in traffic is considered overheating?


It's installed but the build isn't finished yet. The engine has been running and breaking in the valves, but there is about a month to go for all the trim etc.


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## Lemans guy (Oct 14, 2014)

Yes I run the flow looper high flow pump, excellent cooling, factory 7 blade fan and shroud which came on AC cars.


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## PontiacJim (Dec 29, 2012)

Temps OK at idle and goes up when driving is a good indicator that there is not enough air flow through the radiator.

OP has a 4-row Champion radiator which he stated was the "big tube." From all my research and trying to find out exactly how big the tubes are - they are .63" diameter which is NOT the big tube radiator. What it is is a 4-row, densely packed .63" tube, radiator core that requires a LOT of air flow to get through all the rows - at a minimum.

OP stated he has aftermarket AC. Most aftermarket AC will attach the condenser right to the front of the radiator core with zip ties - adding more blockage to the radiator itself. The condenser should be spaced away from the radiator core. He says it is not operational, but if it becomes operational, the condenser will put more heat through the radiator core and compound the issue. And, depending on it's core design, tube spacing, fin density, can impede the flow of air going through the radiator.

OP has not said if his car was originally an AC car or non-AC car. AC factory cars have a larger, ie taller, radiator core height. Non-AC uses a core that is 15 1/2" and AC cars have a core that is 17.5". The difference is at the lower section of the radiator support which is dropped down to fit the taller radiator/core. They now make an aftermarket bracket that can be added/welded on to replace the non-AC radiator support. This allows the use of the larger radiator. Photo is below.

From Butler's website:

"The 1964 and 1965 models have inlet/outlet both on the passenger side. The 66-67 models have the inlet moved to the driver side while the bottom outlet stayed on passenger side. Pontiac engineers realized this was a more efficient design.

All filler necks for 1964-67 A-body Pontiacs were in the same spot except for 1965 non AC Tripower cars where the filler moved 4" to accommodate a different fan guard. 

From the factory, most non AC cars had 3 row radiators and a 5 blade fan. The Tripower and heavy duty cooling option non ac cars got 15.5" 4 row radiators with a 7 blade fan and clutch. All AC cars got 17.5" radiators, 7 blade fan and clutch regardless of options. All of these components are available in the aftermarket. 

Fan shrouds:
1964 cars did not use a fan shroud.
1965 AC cars had a metal fan shroud.
1966-67 AC cars had a plastic fan shroud that was essentially the same as the metal shroud."

The AC cars also had a series of rubber air shields to seal up the front of the radiator so that air is forced through the radiator and not around it. My '73 Fury with AC even has these seals between the grille and radiator to channel the air flow. If these have not been installed, it may be worth installing and could not hurt. It is called "1964-1967 GTO Air Conditioning Seal Splash Shield Kit Pontiac" 1964-1967 GTO Air Conditioning Seal Splash Shield Kit Pontiac

So, my recommendations are: get rid of the small tube Champion 4-row radiator. Add the lower radiator bracket for AC if your car was not originally an AC car. Purchase the larger AC 17 1/2" Cold Case 2-row, or 3-row core radiator with the *big 1.25" cooling tubes (or any other brand with big tubes)*. Should be able to use the factory fan shroud you presently have (If you have an aftermarket aluminum fabricated fan shroud - toss it). Add the Hayden HD fan clutch along with the 17" fan. Make sure the fan blades are 1/2 in/1/2 out of the fan shroud to properly work and pull air through the radiator. Add the seal/splash kit. Make sure the AC condenser is not zip tied to the front of the radiator - space it out.

Make sure you have the correct pulleys for AC as it seems there are different sizes which affect fan/water pump speeds.

Use a 180 T-stat (although I like/use 160). If you have 160, leave it. Drill 2 small holes in the brass ring to allow any trapped air bubbles past the T-stat. Sometimes air can get trapped, create a pocket, and cause a hot spot. This just is a preventative and won't hurt.

I like to use a product called "Water Wetter" which seems to drop temps a few degrees on my car when it was running hot. It may be snake oil to some, but my personal experience was that it did at least do something and every little bit helped.

The ethanol gas mixture can run lean by nature. You may want to richen up the carburetor. Lean means hotter cylinders. Inspect your plugs to see how they look. Select the correct heat range. HEI specs used to say gap plugs at .060", then .045". Gap plugs no more than .040" and I still would go with .035" which is my opinion/choice.

Verify your HEI is working. You want to make sure your timing curve does not pull in too fast. Suggest a slow curve that is all in around 3,000-3,500 RPM's like factory. The factory Intial timing calls for 6 degrees BTDC. Often, it seems 12, 15, and up to 20 works better depending on engine build and cam selection. Advancing the Initial more changes all parameters within the distributor's curve ad total advance and each aspect of the timing will need to be adjusted as well. Make sure the vacuum advance is working and provides 49-52 degrees of total advance with light throttle/off throttle response as this cools the engine under light/no load. If the advance is too much, you will have to use a limiter as too much total advance with the vacuum cannister is not good.

These are my suggestions and what I would be looking at to get engine temps under control.


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## hot 65 (11 mo ago)

I think you may have mis understood, sorry if I wasn't clear. Full shroud , 17 inch fan no clutch , no fan mounted on the radiator which is a 4 core Champion aluminum. I have considered adding a fan but have heard pros and cons on that. Open to suggestions on that also. Going to start with the timing issue first and the address the water pump issue. I will pull it apart check and see which divider plates I have, if they have a notch I will try and find some that do not. Then the plan is to install the Flow Cooler high flow water pump that I bought and installed originally. Hopefully that will solve my problem before I dump a bunch of money into a 11 bolt conversion set up. The Tec. guy at Ames said the 11 bolt didn't make much difference. Thats why I am reaching out to you guys who have way more experience than me. I really apricate all the feed back that I am getting from the site. Sometimes it's a lot for my pea brain to absorb. I am open to any and all advise.
Thanks


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## Baaad65 (Aug 29, 2019)

Great stuff as usual and I've heard going with the large tube 2 core is the best also and that's what I did. Mine is nice and cool while I'm moving it's sitting still that raises the temperature and I know it's because of having no shroud but it's gotta look cool man 😉 that's why I did the pusher fans for when I'm not moving, you hardly can see them.


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## hot 65 (11 mo ago)

PontiacJim said:


> Temps OK at idle and goes up when driving is a good indicator that there is not enough air flow through the radiator.
> 
> OP has a 4-row Champion radiator which he stated was the "big tube." From all my research and trying to find out exactly how big the tubes are - they are .63" diameter which is NOT the big tube radiator. What it is is a 4-row, densely packed .63" tube, radiator core that requires a LOT of air flow to get through all the rows - at a minimum.
> 
> ...


Thanks for all your suggestions. Again what do I know about radiators . Champion made it sound like the was the deal. The car was a non AC car when I got it. No the condenser isn't mounted to the radiator. The shroud is the plastic molded one but it doesn't have the seal around it. I will swap out the radiator as you suggested and add the seals around the shroud. I will also add the fan clutch. I have a 160 stat and I will drill a couple holes also . I just posted before I read yours on the water pump and divider plates and my intention to replace. As for the timing and spark plugs I will also address that issue the best I can. I may have to get some help with the distributor, it's beyond my knowledge. I have started thinking I should just remove the after market air because of the over heating. What are your thoughts about that.
Thank you very much for taking the time to go through everything.


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## PontiacJim (Dec 29, 2012)

hot 65 said:


> Thanks for all your suggestions. Again what do I know about radiators . Champion made it sound like the was the deal. The car was a non AC car when I got it. No the condenser isn't mounted to the radiator. The shroud is the plastic molded one but it doesn't have the seal around it. I will swap out the radiator as you suggested and add the seals around the shroud. I will also add the fan clutch. I have a 160 stat and I will drill a couple holes also . I just posted before I read yours on the water pump and divider plates and my intention to replace. As for the timing and spark plugs I will also address that issue the best I can. I may have to get some help with the distributor, it's beyond my knowledge. I have started thinking I should just remove the after market air because of the over heating. What are your thoughts about that.
> Thank you very much for taking the time to go through everything.


I hate that you are having this issue and am sure you want to simply be driving your car - its that time of year.

I am no radiator expert, but did a lot of internet searching and reading other forums/posts. The Champion radiator has more cores with smaller tubes which gives you slightly more surface area for cooling, but with 4-rows, I think you lose the advantage of the 4-rows because you need more air flow to really draw through the core. Seems those with the bigger CFM twin-electric fans do OK, but anything less seems to be a problem. If I took a survey, more users were happy with the larger tube 2-row Cold case and kept their engines cool. The larger tubes provide more surface are, tube-for-tube as compared to Champion, and with a thinner 2-row, should draw air though it better. Cold Case will be what I go with on my '68 Lemans.

There are other quality radiators as well, but the prices go up. Champion is still a good radiator, I have one in a 1948 International, and pricing is good, but I think the issue here is tube size & row number and using the stock fan/water pump assembly. If you went resto-mod and added the big CFM electric fans, then you probably would be OK.

You could call Cold Case and speak with them and get their recommendation. I can't guarantee their radiator will turn things around - I don't know anything about your car other than what you tell us and there are several things as I pointed out that can contribute to oveheating, not just the radiator. With the hundreds of thousands of Pontiac produced in 1965, if cooling was an issue back then, car sales would have plummeted and dealers would have been pulling out their hair with all the cars coming in with cooling problems/warranty work.

No need to remove the AC at this time. Just don't want that condenser stuck to the front of the radiator core.

Do 1 change at a time and then see what results you get. Making several changes at one and then trying to figure out what may or may not have worked will only add to more frustration and disappointment, not to mention money spent if what you have done does not show any improvements.

Start with the flow-cooler pump/new non-cut out plate, and clearance the impeller. Purchase/install the radiator baffle kit - this is something you can use with the present radiator or a replacement. This will help direct air flow through the radiator. Seal around the radiator shroud so the fan draws through the radiator and no around/past any openings between shroud and radiator.

Install the 160 T-stat and drill two 1/8" holes in the brass ring. Add a bottle of "Water Wetter" which you can buy at most autoparts stores.

When you run your engine, leave the radiator cap off and look inside and watch to see that the T-stat opens and you see water moving. Then you can put the cap back on.

Being a new engine, it can run a little hotter until things get worn in. Not sure what oil you are using? Make sure you are not using 20W-50 as that is too thick and can also add to engine heat.

Give that a try and then up date us with results and we can go from there.


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## 1964oldgoat (Aug 7, 2020)

Jared said:


> So, no shroud? Just the electric fan attached to the radiator directly (zip ties or something similar?)? That would be the first area I'd look at.


That’s correct - no shroud. As I understand it 64 non-AC cars didn’t have shrouds. But mine does have the electric fan attached firmly to the aluminum radiator. Are there aftermarket shrouds you’d recommend? Or do you think the hi-perf water pump should fix my problem? Also, do I have a problem? 200-210 in 90 degree heat and traffic. 190-200 otherwise.


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## Baaad65 (Aug 29, 2019)

I think that's pretty good in that heat, Pontiacs always run hotter, if you hit 220 I would start to get concerned. If you do things outlined here you're going to drop the temp and be in good shape 👍


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## 1964oldgoat (Aug 7, 2020)

Thanks Baaad65 - really appreciate the knowledge. Definitely going to do some of the things you guys have suggested.


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## BearGFR (Aug 25, 2008)

1964oldgoat said:


> Thanks Baaad65 - really appreciate the knowledge. Definitely going to do some of the things you guys have suggested.


Divider plate clearance is also critical. That's the metal plate that sits directly behind the water pump impeller. 
If the clearance isn't right the pump won't move enough coolant, none of the other fixes will be effective, and you can end up throwing money at parts only to find out that nothing helps much.

The distance between the inside edge of the large hole in the middle needs to be only as far from the impeller blades as the gasket between them is thick - and no farther. An easy way to set it is to remover the pump, remove the gasket between the plate and the pump, lay the plate on the back of the pump (with no gasket), then "work" the plate with a 'convincing tool' until it's just barely touching the impeller blades all the way around. When you reinstall the assembly with a gasket, it'll be right. 
Also the kind of pump impeller matters. This kind doesn't work very well (image is not a Pontiac pump, but you get the idea):
Don't use a pump with this kind of impeller

These are MUCH better:
This is the style to use
...Or this style (Flowkooler)

Bear


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## motown (Jul 7, 2018)

Last year I was in almost the exact same position as you after a fresh rebuild of my '66 389 4bbl. I have the smaller core support and a non-A/C car. I had no shroud and IIRC a 19" clutch driven fan. The rebuild is a + .030" with 9.5/1 compression, a tripower cam, stock pistons, fresh rebuild on the original carb and a 4 row stock radiator. I have retained the original timing cover with an unknown brand of aftermarket cast iron water pump. I hit temps of 205-210 before shutting it down.

I found that my timing was off, the shop that assisted with install set it with the vacuum hose on which made it basically TDC (zero advance) at idle. I reset it to stock specifications, added Ames plastic shroud and a Hayden 2797 clutch (it's the Pontiac Severe Duty model which has very little clutch action) and a matching steel 17" fan (both from Summit).As others have suggested, the fan ends up halfway into the shroud.

I drilled a few 1/8" holes into the 160 degree thermostat to ensure no air pockets as well. I now see temps at maximum with the needle touching the middle line (I think 185? I have the car in storage)on the hottest summer days last August. The only time it passed that line was while in heavy stop and go traffic for ten minutes and it was just slightly over that line. I am still in break in mode with 300 miles on the new engine so all activity has be at or below ~3000rpm and it runs 180-185 on a hot day while fully warmed up. I expect that number to drop this year as the engine loosens up a bit. 

Good luck with the updates, I will be watching for your progress.
Mark


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## motown (Jul 7, 2018)

PontiacJim said:


> Temps OK at idle and goes up when driving is a good indicator that there is not enough air flow through the radiator.
> 
> OP has a 4-row Champion radiator which he stated was the "big tube." From all my research and trying to find out exactly how big the tubes are - they are .63" diameter which is NOT the big tube radiator. What it is is a 4-row, densely packed .63" tube, radiator core that requires a LOT of air flow to get through all the rows - at a minimum.
> 
> ...


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## PontiacJim (Dec 29, 2012)

motown said:


> Last year I was in almost the exact same position as you after a fresh rebuild of my '66 389 4bbl. I have the smaller core support and a non-A/C car. I had no shroud and IIRC a 19" clutch driven fan. The rebuild is a + .030" with 9.5/1 compression, a tripower cam, stock pistons, fresh rebuild on the original carb and a 4 row stock radiator. I have retained the original timing cover with an unknown brand of aftermarket cast iron water pump. I hit temps of 205-210 before shutting it down.
> 
> I found that my timing was off, the shop that assisted with install set it with the vacuum hose on which made it basically TDC (zero advance) at idle. I reset it to stock specifications, added Ames plastic shroud and a Hayden 2797 clutch (it's the Pontiac Severe Duty model which has very little clutch action) and a matching steel 17" fan (both from Summit).As others have suggested, the fan ends up halfway into the shroud.
> 
> ...


Yep, timing is extremely important and there have been a couple members who cured their hot engine issues by setting up their timing correctly. That has already been suggested.


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## Jared (Apr 19, 2013)

1964oldgoat said:


> That’s correct - no shroud. As I understand it 64 non-AC cars didn’t have shrouds. But mine does have the electric fan attached firmly to the aluminum radiator. Are there aftermarket shrouds you’d recommend? Or do you think the hi-perf water pump should fix my problem? Also, do I have a problem? 200-210 in 90 degree heat and traffic. 190-200 otherwise.


So just to clarify, you have just and electric fan attached directly to the radiator or the electric and an original style mechanical fan? I think there was a second guy asking similar questions on here so I want to make sure I have your set up correct.

I'll address this as if it's just the electric fan. By attaching the fan directly to the radiator you change the cooling area of the radiator from the entire surface to just the area where the fan is attached. With the shape of the radiator used in the Pontiacs, that would mean the fan is cooling less than half the radiator at best. Depending on the size fan, it could be way less. A good electric fan set up will have a shroud that seals in the fan, or fans, to the inside of the radiator and but brings them a couple inches away so that they draw air through the entire radiator. Look on the Cold Case website and check out what they sell as a kit for the GTO. While you don't have to buy through them, their setup is basically what you want to have if running electrics. I actually bought their electric fan set for mine (shroud and 2 fans) and didn't use them. The factory shroud and fan clutch was enough to keep mine cool and mine is far from stock (461, ported heads, with an aggressive cam). Mine being a 70 has a better shroud design than the older cars did.


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## Baaad65 (Aug 29, 2019)

I'm running the biggest electric puller fan that would fit a 16" tight to the radiator with no real shroud and if you look there is very little surface area being blocked so when I'm moving it stays nice and cool, sometimes not even needing to turn the fan on. I've read and talked to guys with the shroud and fan set up like you described and they said it actually gets hot when moving because the shroud is blocking air flow unless it's vented with flaps that open up or you have to have real good fans on all the time to make up for the air that would be pushed through the radiator naturally. Yes when standing still in the heat is where I get hot with no shroud so I added two 13" pusher fans on a separate switch, now almost all my radiator has air flowing through it accept the top corners. And I still run cool moving down the road so all those fans aren't blocking that much air flow, this is on a 461 with 9:4 compression, hot cam, iron ported heads, and exhaust manifolds...this is just my experience your results may very.


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## vettvet (Oct 17, 2013)

hot 65 said:


> The radiator is mounted in the original position. After market AC but It's never been hooked up, never a belt on it. I been considering just removing the AC all together due to the problem. AS of now the condenser is not restricting air flow.
> 
> Yes it is a stock filter. What would a stock oil filter have to do with over heating? Sorry if it's a stupid question I am not a mechanic by any means.


Is it a long canister with a filter element and a center bolt?


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## hot 65 (11 mo ago)

vettvet said:


> Is it a long canister with a filter element and a center bolt?


Nope, just a standard filter


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## 1964oldgoat (Aug 7, 2020)

Jared said:


> So just to clarify, you have just and electric fan attached directly to the radiator or the electric and an original style mechanical fan? I think there was a second guy asking similar questions on here so I want to make sure I have your set up correct.
> 
> I'll address this as if it's just the electric fan. By attaching the fan directly to the radiator you change the cooling area of the radiator from the entire surface to just the area where the fan is attached. With the shape of the radiator used in the Pontiacs, that would mean the fan is cooling less than half the radiator at best. Depending on the size fan, it could be way less. A good electric fan set up will have a shroud that seals in the fan, or fans, to the inside of the radiator and but brings them a couple inches away so that they draw air through the entire radiator. Look on the Cold Case website and check out what they sell as a kit for the GTO. While you don't have to buy through them, their setup is basically what you want to have if running electrics. I actually bought their electric fan set for mine (shroud and 2 fans) and didn't use them. The factory shroud and fan clutch was enough to keep mine cool and mine is far from stock (461, ported heads, with an aggressive cam). Mine being a 70 has a better shroud design than the older cars did.


Thanks for the info and recommendations. That all makes great sense.


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## geeteeohguy (Feb 2, 2008)

All great advice here. I've driven nothing but 8-bolt pre 1968 GTO's for the past 45 years and have had hot issues with several. The water pump plate clearance is pretty crucial. I like mine at about 1/8". I also paint the plates and the inside of the aluminum timing cover with Glyptal, which is an epoxy insulator coating for electric engines, etc. It prevents electrolytic corrosion of the aluminum, which can be an issue with 55 year old aluminum. I run original type cast impellor water pumps. Not the stamped blade type. I have run both clutch type and flex type fans. I run a Hayden clutch and 19.5" AC fan on my '65 GTO with a shroud and a 18" seven blade GM flex fan on my '67 GTO off of a '69 Cadillac. Both work well. Also run a shroud on the '67. Have had cars run 'hot' due to bad dash grounds causing guage to read high 20+ degrees. Have also had generic NAPA temp sensors indicate high temps. My solution was using Lectric Limited senders. If your car is cool in town but hot on the highway, agree that the fan is ok but the rad or timing curve/fuel mixture too lean could be causes. A true 210-220 temp going down the road won't hurt a thing.....unless the hotter temps lead to engine detonation or fuel percolation. I drive my cars year round, and where I live, summer daytime temps get over 110 degrees. Still running the old stock 8 bolt set-ups!


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## hot 65 (11 mo ago)

geeteeohguy said:


> All great advice here. I've driven nothing but 8-bolt pre 1968 GTO's for the past 45 years and have had hot issues with several. The water pump plate clearance is pretty crucial. I like mine at about 1/8". I also paint the plates and the inside of the aluminum timing cover with Glyptal, which is an epoxy insulator coating for electric engines, etc. It prevents electrolytic corrosion of the aluminum, which can be an issue with 55 year old aluminum. I run original type cast impellor water pumps. Not the stamped blade type. I have run both clutch type and flex type fans. I run a Hayden clutch and 19.5" AC fan on my '65 GTO with a shroud and a 18" seven blade GM flex fan on my '67 GTO off of a '69 Cadillac. Both work well. Also run a shroud on the '67. Have had cars run 'hot' due to bad dash grounds causing guage to read high 20+ degrees. Have also had generic NAPA temp sensors indicate high temps. My solution was using Lectric Limited senders. If your car is cool in town but hot on the highway, agree that the fan is ok but the rad or timing curve/fuel mixture too lean could be causes. A true 210-220 temp going down the road won't hurt a thing.....unless the hotter temps lead to engine detonation or fuel percolation. I drive my cars year round, and where I live, summer daytime temps get over 110 degrees. Still running the old stock 8 bolt set-ups!


Thanks for the advice. I am looking for that 19.5 fan and plan on the Hayden clutch now


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## RMTZ67 (Mar 12, 2011)

Just curious....has it ever boiled over? My engine build is relatively new, about 500 miles now and it was seeing temps about 220. Tried many things to bring it down with small success. But never boiled over or had a hard start when hot. Still doing just fine and my heat panic disorder has subsided. So what am saying is, is it really over heating?
Keep the fluid level down at least one inch below the cap. 
Tried temp gun but very hard to tell what your exact temp is. What type of gauge do you have.


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## Baaad65 (Aug 29, 2019)

With the tempature laser hows the difference between the top and bottom of the radiator, I think it should be about 20° difference then you know your radiator is working.


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## hot 65 (11 mo ago)

Baaad65 said:


> With the tempature laser hows the difference between the top and bottom of the radiator, I think it should be about 20° difference then you know your radiator is working.


It's been a while since I shot the radiator hoses, so I don't remember what the exact temps were but there was a big difference between the upper and lower. It was a hard start when hot. I have a lot of work to try and correct things now. I will try and keep you guys up to date. Thanks for all the support.


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## geeteeohguy (Feb 2, 2008)

With these old Pontiacs (or any old car) it's all about 'stack-up tolerances'----meaning every little component in any subsystem (like the cooling system) needs to be in specification for the entire system to work perfectly as designed. Many of the older guys who never experienced heat issues in the day suspect that it's caused by aftermarket water pump impellor depths....the original pumps were pressed to a set dimension, ensuring proper plate clearance 100% of the time. And so on. So, a known good radiator, a good fan and fan clutch if used, a shroud, a proper timing curve, proper fuel mixture (ethanol fuels run 10-15% too lean for stock jetting), and no dragging brakes, etc. Another thing I have heard and have not verified: many new fan clutches are calibrated to come on and engage at about 230-240 degrees, because the newer vehicles run at 220 all the time. On an old Pontiac, you would want that fan to come on around 200 degrees or even 195. Some guys install a smaller 6" water pump drive pulley off of an AC car. Good luck and keep us posted.


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## hot 65 (11 mo ago)

geeteeohguy said:


> With these old Pontiacs (or any old car) it's all about 'stack-up tolerances'----meaning every little component in any subsystem (like the cooling system) needs to be in specification for the entire system to work perfectly as designed. Many of the older guys who never experienced heat issues in the day suspect that it's caused by aftermarket water pump impellor depths....the original pumps were pressed to a set dimension, ensuring proper plate clearance 100% of the time. And so on. So, a known good radiator, a good fan and fan clutch if used, a shroud, a proper timing curve, proper fuel mixture (ethanol fuels run 10-15% too lean for stock jetting), and no dragging brakes, etc. Another thing I have heard and have not verified: many new fan clutches are calibrated to come on and engage at about 230-240 degrees, because the newer vehicles run at 220 all the time. On an old Pontiac, you would want that fan to come on around 200 degrees or even 195. Some guys install a smaller 6" water pump drive pulley off of an AC car. Good luck and keep us posted.


Yea I get it. Been scratching my head for a while. I bought a new 65 in March of 65 never had an issue with over heating in that car.


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## hot 65 (11 mo ago)

PontiacJim said:


> Temps OK at idle and goes up when driving is a good indicator that there is not enough air flow through the radiator.
> 
> OP has a 4-row Champion radiator which he stated was the "big tube." From all my research and trying to find out exactly how big the tubes are - they are .63" diameter which is NOT the big tube radiator. What it is is a 4-row, densely packed .63" tube, radiator core that requires a LOT of air flow to get through all the rows - at a minimum.
> 
> ...


Ok now i am getting more confused. Been talking to Cold Case, they are pushing the combo radiator and fan system. They tell me I can get the 17 1/2 inch radiator with the bigger 1 1 / 4 inch tubes for an up grade of 100 bucks. They say there fans are pretty quiet. I already have the Derale fans which are noisy. So Taking your advise my plan is to add the 2 inches to the bottom of the radiator support. Change out the pump to the flow cooler high volume pump with the Butler divider plates which I will try to clearance. Then go to a 17 1/2 in. clutch fan with a H/D Hayden clutch with shroud and splash kit. Change out all the pullys to the smaller ones. What do you recommend? I still am working on the timing issue but that will all take place at the same time. Do I need the Cold Case electric fans or can I just use the set up i just described? Has anybody had experience with there fans as far as noise? I would prefer to keep it old school. Just tired of throwing money at it. 
I am open to all your thoughts and comments. Thanks


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## PontiacJim (Dec 29, 2012)

hot 65 said:


> Ok now i am getting more confused. Been talking to Cold Case, they are pushing the combo radiator and fan system. They tell me I can get the 17 1/2 inch radiator with the bigger 1 1 / 4 inch tubes for an up grade of 100 bucks. They say there fans are pretty quiet. I already have the Derale fans which are noisy. So Taking your advise my plan is to add the 2 inches to the bottom of the radiator support. Change out the pump to the flow cooler high volume pump with the Butler divider plates which I will try to clearance. Then go to a 17 1/2 in. clutch fan with a H/D Hayden clutch with shroud and splash kit. Change out all the pullys to the smaller ones. What do you recommend? I still am working on the timing issue but that will all take place at the same time. Do I need the Cold Case electric fans or can I just use the set up i just described? Has anybody had experience with there fans as far as noise? I would prefer to keep it old school. Just tired of throwing money at it.
> I am open to all your thoughts and comments. Thanks


My opinion:

Good - 17 1/2" core w/1 1/4" tubes.
Good - adding lower extension to radiator support for larger radiator
Good - drilling 2 1/8" holes in the T-Stat ring. Use a 180 T-Stat, but I have a personal addiction to a 160 T-Stat.
Good - HD Hayden Clutch - BUT, they come in 2 lengths and being you have the 4" 8-bolt water pump, I believe you need the longer clutch to get the fan 1/2 in - /1/2 out of the radiator shroud - a little more in is better than more out.
AC Pulleys - Bigger on crank, smaller on water pump. Believe correct size is 8" on crank and 7" on the water pump to spin the water pump a little faster.
Good - Splash Kit
Not so good - 17" fan and shroud. You are increasing the core size of the radiator so my thinking is the shroud will now be too short and not fully cover the bottom/top/both of the radiator depending on how the shroud sets on the radiator. I would step up to the 19 1/2" seven blade AC fan and correct matching shroud.

Not so good - Electric fans. You mentioned you have Derale fans - assume in front of the radiator? Electric fans in front of the radiator WILL block air flow. They should be mounted as puller fans to draw air through. BUT, some of these have real crappy aluminum shrouds that only create additional problems as they do not sit tight to the radiator, are not the correct depth within the shroud opening, or don't pull enough CFM's. This will show up at cruising speeds, but keeps the engine cool at idle and very low speeds.

*Here is a post by GTO44 on electric fans,*

"The real question is how much air do those electric fans move...
Not all electric fans are created equal. They should be rated at least 2,000cfm - 2,200cfm a piece. Anything under 4,000cfm total will not cool an engine like this. Some electric fans are flat blades which are designed to be quiet. These may only pull 1,000-1,200 even being a 12” fan. The curved blades fans are the ones you want. It should like a 747 spooling up... if not than you got the wrong fans." 

NO to electric fans if going back to factory cooling. BIG fans and matching shroud if using electric fans - the noisey ones.

*I worked with another member with a '65 and 455CI/ standard 389 pulleys/Tri-power/200R4 trans and was having cooling issues. * Here is the bottom line after trying different approaches and keeping the dual 10-bladed SPAL 932 CFM electric fans - which were really too small in CFM's and I felt the 10-blades made more of an air dam when not spinning. And, no vacuum advance and a bit too much timing was also part of the issue:

"My non-a/c, auto- trans 1965 GTO with 455 with dual electric fans on my Griffin radiator. I dumped the electric fans with custom shroud and went with stock type mechanical fan, clutch, and shroud. Any cruising speed it doesn't go over 180 degrees. I drove my car in a 4th of July parade for approx. 2 miles @ idle speed, perhaps lasted 45 minutes. Pretty much the same as if I was in a traffic jam. The engine temp was pretty high between 230 - 240 degrees, monitored by both mechanical and electronic gauges. As soon as I drove it away @ 30 mph, the temp went back down to normal (here is what I felt was a vacuum advance/timing issue - read next paragraph). 

Also I checked my timing. * *Vacuum advance is not hooked up, because my engine builder said I didn't need it.* So when I checked the timing last week, It was 24 degrees advanced @ idle and 42 degrees @ 3,000 rpm. Before the parade, *I set the timing to 19 degrees @ idle and 38 degrees @ 3,000 rpm*. I tried to get it down to 18/36 degrees, but when I tightened up the distributer; it would slightly shift. I tried 16/34 degrees and the engine didn't sound too happy!!

Well, 42 is an engine killer in my book with iron heads and should really be pinging badly. 

As per your advice, I lowered my timing down to 14 degrees BTDC and then re-hooked up the vacuum advance despite what my engine builder told me. The results are 180 degrees cruising 202 degrees sitting in traffic. 

I do notice one thing when I mash down on the gas pedal, it sometimes pings just a little bit. My motor has 10:1 compression and I run 93 octane. I found that the rear carb and the intake manifold, cylinder head head side has a slight vacuum leak. I tightened the bolts, but it didn't make a difference. So I believe at higher rpm's when I hear the pinging the vacuum leak is probably causing a leaner mixture." 

So the above was what this member began with, a hot engine, and what he ended up with after a few changes going back to a stock set-up. If he had had some really bigger electric fans, maybe there would have not been an issue, but I can't say one way or the other. *GTO44 *uses electric fans on his customer builds and has the experience/knowledge far more than I.


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## hot 65 (11 mo ago)

PontiacJim said:


> My opinion:
> 
> Good - 17 1/2" core w/1 1/4" tubes.
> Good - adding lower extension to radiator support for larger radiator
> ...


I figured I would need to go to the bigger shroud I will see if i can find a 19 1/2 inch fan. If you have any thoughts on where to get one. The fans are Derale dual 3750 cfm mounted motor side of radiator they are pullers. Like the article you sent me they do sound like a plane taking off. I will take your advise and go for the bigger fan and shroud. Thanks.


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## PontiacJim (Dec 29, 2012)

hot 65 said:


> I figured I would need to go to the bigger shroud I will see if i can find a 19 1/2 inch fan. If you have any thoughts on where to get one. The fans are Derale dual 3750 cfm mounted motor side of radiator they are pullers. Like the article you sent me they do sound like a plane taking off. I will take your advise and go for the bigger fan and shroud. Thanks.


OK, sounds like a plan. Doing a little more research/reading up on electric fans. Seems some have free flow CFM ratings and not a CFM rating when installed behind a radiator - which can drop the effective CFM's down depending how thick the radiator is. The other thing has to to with the electrical system and how you have the wiring connected, and mainly the gauge of the wire so you don't lose any voltage going to the fans because the wire gauge is too small. If you get a voltage drop due to too small of a wire gauge or any form of resistance, this will slow the speed of the fans down. 

Just more info for you.


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## hot 65 (11 mo ago)

PontiacJim said:


> OK, sounds like a plan. Doing a little more research/reading up on electric fans. Seems some have free flow CFM ratings and not a CFM rating when installed behind a radiator - which can drop the effective CFM's down depending how thick the radiator is. The other thing has to to with the electrical system and how you have the wiring connected, and mainly the gauge of the wire so you don't lose any voltage going to the fans because the wire gauge is too small. If you get a voltage drop due to too small of a wire gauge or any form of resistance, this will slow the speed of the fans down.
> 
> Just more info for you.


The fans were installed per Derale specs. 10 gauge main feed 2 relays they provided and I am running a 100 amp alt.


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## PontiacJim (Dec 29, 2012)

hot 65 said:


> The fans were installed per Derale specs. 10 gauge main feed 2 relays they provided and I am running a 100 amp alt.



OK, just trying to cover all bases and rule out a drop in volts going to the fan motors and slowing their speeds from the advertised speeds and not pulling enough advertised CFM's.


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## hot 65 (11 mo ago)

PontiacJim said:


> OK, just trying to cover all bases and rule out a drop in volts going to the fan motors and slowing their speeds from the advertised speeds and not pulling enough advertised CFM's.
> What do you think of the OER 7 blade fan . It says 19 1/2 inch. Having trouble finding a 19 inch . Any suggestions?


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## PontiacJim (Dec 29, 2012)

It seems this one may be what you want, 7 blade 19 1/2". It does not say for '65 GTO, but shows being used on later Pontiacs. You can see in the pictures the pitch of the blades. Then you want the 21" diameter fan shroud. I did see a number of 19" fans, but not sure if they would work. 









3991431 - 1971-79 Buick, Chevy, Olds, Pontiac; 7 Fan Blade Fan; 19-1/2


OER® Authorized reproduction of the original 7 blade fan designed for use with a variety of 1971-79 Buick, Chevrolet, Oldsmobile, and Pontiac models as listed.




www.classicindustries.com





Here is a post that mentions the longer and shorter version of the Hayden clutch. You have the 8-bolt 4" water pump, so it looks like you will need the longer clutch #2747. You can check by exact application on the Hayden website at www.haydenauto.com. If you need further assistance you can call the tech line at 866-502-0068.









Clutch fan height for a 1965 LeMans "franken-car"


I have a 455 out of a '73 Bonneville in my '65 Lemans. The engine has the 11 bolt 4.5" water pump of course. What size/height fan clutch do I need? I've had a flex fan on the car for years and am tired of the aircraft prop noise while cruising down the freeway. Do I need to order a clutch...




www.gtoforum.com


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## hot 65 (11 mo ago)

PontiacJim said:


> It seems this one may be what you want, 7 blade 19 1/2". It does not say for '65 GTO, but shows being used on later Pontiacs. You can see in the pictures the pitch of the blades. Then you want the 21" diameter fan shroud. I did see a number of 19" fans, but not sure if they would work.
> 
> 
> 
> ...


Thanks for the info. on the clutch. Most of the fans are not specific to a 65 and not much information on the pitch of the fan blades. I will try to dig a little deeper on them. Some post I have read says try finding one in a older GM car in a wrecking yard. The OER I can get from summit which is close to where I live


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## PontiacJim (Dec 29, 2012)

hot 65 said:


> Thanks for the info. on the clutch. Most of the fans are not specific to a 65 and not much information on the pitch of the fan blades. I will try to dig a little deeper on them. Some post I have read says try finding one in a older GM car in a wrecking yard. The OER I can get from summit which is close to where I live


If you have the '65 Service/Chassis Manual, the fan specs are in the cooling section. I looked at my '68 manual and it lists the 19" fan, but also lists the 19 1/2" fan for AC. And there is the 4-bladed metal fan, but not a good choice ever for HP. So stick with the 19 1/2". Yes, I have read there are other makes/years that will fit/work, but I am not up on junk yard hunting hoping to find the one I need - unless we could turn the clock back to about 1974 when they still had the "good" junkyards and the owners knew what you needed.


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## hot 65 (11 mo ago)

PontiacJim said:


> If you have the '65 Service/Chassis Manual, the fan specs are in the cooling section. I looked at my '68 manual and it lists the 19" fan, but also lists the 19 1/2" fan for AC. And there is the 4-bladed metal fan, but not a good choice ever for HP. So stick with the 19 1/2". Yes, I have read there are other makes/years that will fit/work, but I am not up on junk yard hunting hoping to find the one I need - unless we could turn the clock back to about 1974 when they still had the "good" junkyards and the owners knew what you needed.


I definitely get that. I do have the manual for the 65 I will check it out 
Thanks


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