[BILTIT]

Plug color can only be used for WOT mixture. You cannot use plug color for idle mixture.

[Vet65te]

OMT - Three out of the four pics I submitted do make it look like it's quite a ways back from the opening but the very first pic taken from the passenger side gives a better perspective. The bottom half blades are half-in, half-out, but the upper blades are only barely inside the opening. Everthing is new including motor mounts and nothing is tweaked or bent so I suspect its just the shape of the shoud that makes it uneven.
I will probably look around to see if I have a slightly longer spacer, like a full inch instead of the half-inch one that's on there now, in order to tuck a bit more of the fan blade into the shroud opening. At this point, it couldn't hurt to try a slight adjustment. As far as the up and down positioning is concerned, I have it pushed as far down as it will go in the attaching slots of the shroud.

[Hurst65]

Vet,
My radiator is a 3 core with the in and out on the pax side. Probably just like yours. It works. I would like it to run a little cooler but, it does not over heat. One of these days I will go with a 4 core factory style radiator.

My fan also has alum. blades. Its hard to tell in my picture but, the tips of the blades also have the rolling that you're refering to. But, do you notice how there is a noticeable difference in blade surface area?

I think if I was you I would consider getting a newer fan shroud (the ones that have the ribs on the sides) and see how it fits. If it's not any better you could send it back...?? I would be leary of spacing that fan out much further. To me the shroud should fit correctly and you should not have to make the fan fit the shroud. That just seems like the wrong approach to me....

[Vet65te]

Hurst - I will look around for a slightly thicker spacer in order to kick the fan a bit more into the shroud but I am not expecting a significant change in temps. After all the evaluation that has gone into this car, I suspect the ring friction is to blame for the lions share of the overheating problem. If I can pick up a percentage point by adjusting the fan location, I will try it.

I am also going to pursue the smaller water pump pulley approach. I have a Chevy twin groove pulley that is 7-inches in diameter but it's 2 3/4 inches high which means I'd have to space out the pulley from the water pump flange by about a 1/4-inch in order to keep the belts lined up. Not a big issue. The other issue is that the Chevy 4-bolt pattern is tighter than the Pontiac which means I need to redrill to suit, again not a big deal. As long as I can drop the diameter of the water pump pulley from the existing 8-inches to somewhere around 7.25 to 7.00 inches I'll wind up increasing the water pump and fan speed by about 10 to 15% at the same rpm and after seeing the engine stop it's temp rise when the electric fan kicks in it tells me that additional airflow should help.

Fan Shroud - Not sure if you took a look at what Performance Years offers but it's almost a carbon copy of what I already have. I suspect that there can't be too many manufacturers of these shrouds. I'll probably keep my eyes peeled for another early GTO at some of the upcoming shows and see what they are running and if I find something that seems to fit better, I'll try it.

I've got an article saved in my stash of parts that talks about 'adjusting' the external spring on Thermally Activated Fan Clutches. The problem is, they don't exactly tell you which way to turn the spring. They suggest you unclip the spring from it's current position and rotate it approximately 180* to the other side. They go on to say you'll feel some resistance but if you try to turn it the 'wrong way' you'll find a bunch of resistance. Ooookay, so which way to turn. I have a brand new clutch unit and looked at it carefully and the tang on the opposite side has no slot so you'd have to rest it on the outside of the tang. I tried turning it both ways and it moved fairly easily each way. Anyone try this, in an attempt to increase the lockup point of their clutch fan?

[Old Man Taylor]

The intent of this picture was not to show the fan, but you can still see that it sits in the shroud uniformly, and the center of the blades are pretty close to the edge of the shroud. Since the car is running again I will try to get a better picture. The fan is a factory flex fan and the shroud is also a factory item. As I recall it was a '65 taxi option. I lightened the picture a lot so you could see the fan better.

[Vet65te]

Thanks for the picture. I will keep an eye open at the upcoming car shows to see what others are using on 64/65 GTO/Lemans. So far, the only ones I've seen listed for use on 64's all look like the one I have and while I do feel it's better than nothing, it's not exactly a perfect fit. If no other shroud seems to be better than what I have I will at least increase the spacer size in order to push the fan blade a bit further forward. I don't really expect to see a major change from that but at this point, a few percentage points better here and there can have a cumulative positive effect. I'm now up to a whopping 171 miles on the new drivetrain. At this rate I'll be ten years older by the time I get a couple thousand miles on it.

[Dick Boneske]

You have posted for several days now about the fan shroud and other cooling system details. Did you read my answer to your post about my experience with my '64? It had no fan shroud when it was new from the factory. IT NEVER OVERHEATED. After I modified the original Tripower 389 with various cams, headers, higher compression, it still NEVER OVERHEATED. Then, I put a 428 +.040" over with Tripower in the car and it still DID NOT OVERHEAT.

If you will please forget about the shroud, fan design, fan spacer, fan clutch, water pump pulley, timing, electric fan, all the other things you've been talking about and put a stock 4-core radiator in the car, your overheating problems will be over and you can enjoy driving the car. Very easy fix with not a whole lot of money spent.

Sorry for the rant, but you have been overlooking the one item that will fix your problem.

[Vet65te]

Hey Dick, take a deep breath and relax, it's not 1964 anymore and these things happen. If you've actually read any of what's been written you'll see that a number of issues have been raised and obviously this isn't 1964 and these aren't fresh off the showroom floor. Just read any of the various manuals and you'll always find 'numerous' fixes for any malady with the most common fixes at the top of the list. There are a number of things that could contribute to this issue and yes indeed a bigger radiator could fix it and it may not. This is a non-A/C car and the radiator that was in the car when I bought it was a 3-row core. There have been a number of contributors to this thread that have tripower cars and seem to have 3-row cores and so far, I haven't found anyone having an issue with the 3-core radiator.
If a 3-row radiator without a shroud was stock for a non-A/C car, why would you consider a move to a 4-row radiator as any different than pulley changes, or electric fans. A crutch is a crutch but for now, I don't intend to drive the car without those 'crutches'. If it's too painful to read this thread...don't.

[Dick Boneske]

Vet65te,
I'm trying to be anything but a pain in trying to understand this thread. Yes, the subject has been beaten to death. Of all the intricacies of our old Pontiacs, this is one of the simpler ones to resolve. If you begin restore the cooling system to the same components--or better--than how the car left the factory, they don't overheat. These items are hardly "crutches." I have found no evidence to show any Tripower '64 GTO was shipped without a 4 core radiator. I don't understand your reluctance to go that direction. Those that have responded with 3 core radiators must have made other changes to compensate for the smaller radiator.

In addition to the '64 GTO I bought new, my wife's '64 Tripower GTO with a 428 +.040" overbore has no shoud, no extra fan spacers, special pulleys, etc. It NEVER overheats. It does have the stock 4 core radiator.

[Pontirag]

in 1964 both the AC cars and the tripower cars came from the FACTORY with the larger 7.5 inch 4 core radiator. Steel shrouds ditto. Zazarine and roberts Pontiac Restoration Guide, 1985 edition. Page 357 on the radiator info and 366 on the shroud info.

so whats the beef?

I agree with mr Boneske on the overheating issues. keep the cooling system factory with no funky azzed pulleys or thermostat restrictors and you should have no problems. At least you can eliminate that area as a problem.

Its usually ignition or fuel.

I has a 2 core x 15 inch six cylinder radiator without shroud on a 64 with a 67 engine/66 tripower combo and it never overheated driving at 75 mph from Colo Springs to Denver. It crept up to about 200 degrees comminhg off the off ramp down to a light but she never blew her top. This subject has been beat to death in cooling and heating.

lets call a time out on the purchas of shiny new parts and actually troubleshoot the system. Starting with what ya did to it to cause the overheating to begin with.

Check your fuel and ignition systems. Try cooler or hotter range of plugs. Keep #5 and 7 wires away from each other. Explore different brands/quality of gasoline. Solve oil consumption problems. be sure your Pcv valve is correct, working and in the proper location. Ckeck your ignition timing with a light and be sure that tdc on the balancer is the same as TDC acoriding to the cam. Oil consumption will cause overheating but in the voluems needed to cause it you will need a rebuild.

Service the cooling system, flush it and check the housing, pump and sundry other components for servicability.

There are issues with the dead space between the impeller blades and the devider on rebuilt and aftermarket pumps. Some people recomend punishing the devider by beating it to death while others have realised the impeller sometimes is pressed too far onto its shaft and cleverly think of a way to pull it back off a little. Clearly this solves alot of issues but not all.

Some people swear by a restictor in place of the thermostat while others swear at it. The current trend is that it is NOT a good idea. As it is only the latest cycle in this particular trend this too shall pass. Currently stainless steel restrictors are the do all end all solution. My 4 dollar thermostat is 32 years old and my car does not overheat.

Only thing really any better than a 17.5 inch 4 core AC/Tri power radiator is the same one in aluminium.

I would avoid spacers. Get a correct heavy duty thermostatically controled fan clutch.

Explore different and better quality fuels. try mixing avaition fuel and E85. If that causes the problem to go away then you built the engine with too much compression or the wrong cam

Cams affect dynamic and static compression Static compression is no biggie but if your cam induces a higher dynamic compression it may also by itself and in concert with bad fuel, poorly serviced cooling system or a lack of compatability will certainly cause cooling problems.

Remember... these cooling systems won races at nascar and operated under warrenty in Phoenix in the summer time. Explore the symptoms and experiment but if it dont work go back to step one or you will be forever tring to hit a moving target.

[Old Man Taylor]

I keep reading about shrouds on '64 GTO tri-power cars. I ordered mine new. It did have the HD radiator, but it did not have a shroud of any type.

[Dick Boneske]

OMT,
Ditto for my '64 that I ordered 4-22-1964. No shroud, but heavy duty radiator was part of the 3.90 rearend package with Safe T Track, metallic brakes, speedometer adaptor, and heavy duty fan. A bargain fo $75. Posted invoice in the Heating/Cooling Forum.

[Geoff]

I don't think the 'well it rolled off the production line & was ok' means that the engine should cool as well today as it did in 64.
Quite a few things have changed, & do change over time, that can affect engine cooling & can vary with individual engines.
Here is a quick list & I'm sure these are not all:
Unleaded fuel. Original engine designed to run on leaded fuel with higher octane. Timing may have to be reduced with UL to prevent detonation, runs hotter.
Rust scale in water jackets, some engines affected worse than others, engine runs hotter.
Engine rebuilt/modified/age introduces a wealth of possibilities than can cause hotter running. Retarded cam timing, poor valve seal, quench action reduced or lost, pistons fitted tight, etc.

[Dick Boneske]

Geoff,
I agree with your comments except for one thing. You missed the point I was trying to make----If you begin with cooling system components inferior to "what the production line installed," such as a 3 core instead of 4 core radiator, you're likely to have cooling issues. If you begin with a cooling system equal to or better than the factory installed, these cars won't overheat--even in Phoenix, Arizona or Australia.

[Pontirag]

Also if you are opperating your car outside the envelope and beyond the parameters established by the factory you will have problems.

Blaming the design if you use low octane gas is not a design fault.

Improper servicing of the cooling system either allowing rust scales to develope or failing to remove them is not a factory design fault

retrofitting heavier duty factory designed components will put the successful operation of the engine back within the factory parameters.

I am not saying we should refran from doing anything to our cars to make them better or faster. Just give the engineers a little more credit and perhaps read between the lines of the aftermarket hype. If your car is over heating after you did something to it typically its what you did to it that caused the problem. SOLVE THAT PROBLEM first! dont go and buy a shiny new pump. Of course thats what the pump marketing guys want you to do but dont. determine what the problem is and solve it. Use your head, not your wallet.

and dont be afraid to presume you may have made a mistake. This industry thrives on vanity. That why people trailer thier cars everywhere but talk alot about how might and bad they are. talk is hype too.

[Hurst65]

I agree with pretty much everything that has been said here. However, you guys have forgotten the original problem. Vet says that it gets hot when the engine is at idle or light driving. He didn't say that his car overheated at the drag strip or on the highway with 3.90 gears, Right?? Soooooo, why wouldn't a good factory 3 core radiator be able to cool his "small", relatively stock engine at idle? I really don't consider a 3 core radiator to be a small radiator. Is it the best? No. Would it be better to have a 4 core? Yes. Should I have said 'go out a buy a new 4 core'? I don't think so. I can see if he had a big inch monster engine and was out racing it but, he doesn't and isn't.
Also, my coments on the fan and shroud were just general input for the sake of conversation. I think he should be able to take that shroud completely off and still not have any problems. I would like to have one on mine not only for the hopefully added airflow but, also as a safety device to serve as more of a fan guard. But, I also know that if I buy one and it didn't fit like it should I'm sending the damn thing back.

Oh yeah, the only other changes that I've made to compensate for my smaller radiator is that I set the clearance of the divider plate. I'm using a pump with a cast impeller. That's it, I promise.

[Dick Boneske]

Hurst65,
Did you read the posts? We were trying to make the point that Pontiac shipped these cars with adequate cooling systems--that would operate in Phoenix, Arizona or wherever. Why would you argue in favor of running a 3 core radiator instead of a 4 core on a Tripower GTO? What's so complicated about using what the factory specified or better? They specified a 4 core radiator for Tripower GTO's in '64. Isn't that where we should start?

[Hurst65]

I wasn't trying to argue anything. I'm just one of those guys that tries to make due with what I have before going out and spending a bunch of money on new parts. I was just providing feedback on what worked for me and my experiences with the same issues. That's all.

[jeffhhs76]

Vet65te

Just tossing in my 2 cents... I really don't think you have a problem here. Every GTO I've had ran in the 200-210 degree neighborhood and I never had an overheating issue. Compared to some other GM prods, 60's Pontiacs run hot. That's always been true. The 66's I had in the late 70's (4 of them) all ran around 210 as did the 67 HO' that I had before my current 67'. My current car, before the rebuild, ran dead on at 210 degrees. None of these cars EVER exceeded 210 degrees on the guage. That being said, after the rebuild which is .030 over, comp cam, E-heads, Speed Pro pistons, Edelbrock 750 and Performer RPM, Doug's headers, NO clutch fan and the same stock radiator (untouched except for a pressure and flow test) now runs somewhere around 175 degrees. I can only attribute this to the aluminum heads and intake. I would almost bet that if i used cast iron heads and intake the temps would be up around where yours are.