# Aluminium Radiators, what's the difference?



## Bryan67 (May 20, 2016)

My 67 GTO (less AC) likes to run warm (235) down the highway on days over 80 and won't come back down, runs ok around town w/o a issue! I'm told it's either a tuning issue or the radiator has maxed out, I recall when I put this 4 core copper in back in about 1990 I thought getting down to 235 was good!
Been busy working on the old girl, like to have it ready for most any daily drive this summer so I am up grading timing items but wondering about the radiator, no the 4 core copper isn't plugging inside and has a shroud with the large GTO fan....

Is Aluminium really the way to go or up grade from my 4 core copper? Then I hear stuff like a 2 core w/1" tube is better than my 4 core. Later I see some selling 3 core w/ 3/4" fins and so on...... What can someone tell me about this subject? Then there seems to be a lot of radiators out there (2-3 core) at $200-$250, then $500-$600 but is one really getting something better for an extra $?

Unsure if I should wait until after new timing parts are in, and see what July brings or just do it while the car's in parts.... If nothing else I'll pull the old one to get measurements....for ordering later on but again what's your experiences with radiators?

Thank You, Bryan


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## bigD (Jul 21, 2016)

Most agree that the wide tube 2-row alum will out cool a 3 or 4 row. I'd go with an alum that has 2 rows of at least 1 inch wide tubes. The Cold Case brand gets good reviews, and looks similar to original, when painted. Don't know who has the best prices on these. Ames & Butler sell 'em.

http://butlerperformance.com/c-1307...rnal-cooling-system-components-radiators.html

There are some on Ebay. This ad says these are 1/2" shorter than original. So, they're cheaper. They show an RPE36L & an RPE40L.

66-67 Pontiac GTO Tempest LeMans Aluminum Performance Radiator Cold Case AT | eBay

66-67 Pontiac GTO Tempest LeMans Aluminum Performance Radiator Cold Case AT AC | eBay


This one has 2 rows of 1 1/8" wide tubes. Looks similar to the Cold Case, but does not list a brand name. It's cheaper, @ $199 shipped. Don't know the quality. 

1966-1967 PONTIAC GTO, TEMPEST, LEMANS ALUMINUM RADIATOR 17'' CORE W/FACTORY A/C | eBay


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## Pinion head (Jan 3, 2015)

Have you cked & adjusted the clearance between the waterpump impeller & the divider plates? this is especially important with the 8 bolt waterpumps & the '64-67 radiators. Another point of importance, the impeller used in '64 Pontiac V8 waterpumps has less impellers than the later 8 bolt waterpumps. Original radiator flow '64's need to use the correct less aggressive design impeller. The opposite is true with '66-68's running 8 bolt pump. Ive pulled numerous original casting pumps that had the wrong style impeller.

Another big cooling problem I've run across on early rather stock to moderate performance built '64-67's over the last two decades is poor selection of replacement parts. Cast rebuilder pistons waaaay down in the hole (no quench) along with short timing (timing backed out) along with rich condition contribute to overheating. So many times alum radiators & electric cooling fans are used as a crutch to try and solve other existing problems.


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## Bryan67 (May 20, 2016)

First I could of given more details, like the car is a 67 GTO Conv, 400 WT block, 4 Speed, PS, No A/C, 4 core copper radiator from the early 90's. I ran in a parade (haven't driven much if at all for years) last July and it was about 80 out and the car ran cool, thought gee this is good but once I headed home after 10 miles the temp was about 230, same thing for later on the fall and temp wouldn't drop when I slowed down or drove in town...
Seems to be a lot to learn on radiators, thanks for the good start.

Water pump, no I haven't done anything to or checked beside installing a new one a couple years back from local supply house. I did ask the supply house last fall if I got a HD or what, they didn't know but when they looked up they only offer one. I suppose one of these days or should I say later this sprint I may as well pull the pump and have checked out.

I was reading where if one has too low of a temp t-stat it could effect the cars heating, have you heard this and got a though on it? I have a 160 in now thinking we don't need the heater but the car would start off running cooler, is this a mistake vs running a 180 or 190? Please reply and thanks so much..... Bryan


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## Pinion head (Jan 3, 2015)

Before anything else, I'd unbolt the waterpump, remove it, & carefully inspect the clearance gap between the impeller & the mating flat surface of the steel divider plate. The clearance gap needs to be minimized by bending the flat surface of the center area of the divider plate towards the tips of the impeller. I've tweaked these plates as close as .060. 1/10 of an inch is fine, you don't want several 10ths, that's where many mass rebuilt waterpumps end up, ESP when rebuilt with the wrong cast impeller or with the junk stamped steel impellers. 

I always ck impeller clearance to divider plate as we rebuild original casting waterpumps with original impellers. Once you get the clearance issue solved, reinstall with new wp gaskets, & reattach the PS & alt brackets & belts. next take the car for a spin, get it up to operating temperature, see what your aftermarket temp gauge reads. Personally, on Pontiac V8's, I gave up on substituting 160 degree thermostats many years ago & only run 180-195 degree thermostats.


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## Rushm (Jan 22, 2017)

How does one check the impeller to plate clearance?


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## Pinion head (Jan 3, 2015)

Please reread my last post, it's all in tweaking the center of the divider plate where it gets close to the edges of the impeller.


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## Rushm (Jan 22, 2017)

My question is, once the water pump is sitting against the timing case, how do you check the clearance between impeller and plate.


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## PontiacJim (Dec 29, 2012)

Rushm said:


> My question is, once the water pump is sitting against the timing case, how do you check the clearance between impeller and plate.



You cannot. Check out the "Sticky" above on overheating. As I recall, it is covered in there. Many overheating/running hot problems can arise from too much gap between the impeller and plate and the water does not circulate as well as it should. And as PH has stated, there are different impeller designs and some of the aftermarket rebuilt replacement impellers (stamped steel) are of a poor design and can add to hot running/overheating issues.

You Tube also has a video. Ignore the welded ring you see on the impeller as that is just another version, just pay attention to the clearance between whatever impeller design you have and the plate:


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