A 4-core radiator or an aluminum unit will do wonders. Summit has "Direct-Fit" aluminum units that work well and are reasonable priced.
On the timing issue (sorry, just got back to this thread), you mentioned you advanced the distributor to get highest idle. That puts you in the ball park. Now what a vacuum advance unit would do, when hooked up to full manifold vacuum, will add another 15 degrees of timing at idle. So your initial timing remains low to allow the car to start, but after you start it, the vacuum advance pulls it beyond what the mechanical can do. On a hot running engine, that's what the TVS (thermostatic vaccum switch) did on the 69-up Pontiacs. The switch was mounted in the intake manifold water crossover, and has vacuum hoses sticking out of it. When the engine ran hot (over 210 degrees I believe), the switch would activate, and the vacuum advance would pull another 15 degrees of timing until the engine cooled down. Lots of old Pontiacs don't have this switch anymore, but that's ok, we use full manifold vacuum all the time, or ported vacuum with modified distributor curves.
You don't need this switch for your overheating problem. I was just referring to it as to why brand new Pontiac 455's ran cool when new.
You may want to think about a better radiator. It's tough keeping a a 2nd gen car cool with a 3-core and a 455.
I saw the direct fit radiator in the Summit catalog. The price is reasonable. I called them to learn more and apprently they don't come with the side mounting brackets. Since the brakets on my 3 row are welded to the radiator, do you know how Summit rad mounts?
Not sure who you spoke to, but I'd call them back, and tell them "direct fit" means "direct fit" They bolt in, and they have the side mount brackets.
SUM-380456 (double check that number on the Summit site to make sure)
The only thing you'll have to do is modify how the fan shroud mounts. I drilled a hole in the bottom of the factory shroud, used a sheet metal screw, and used a piece of metal (strap) and ran it to an existing hole in the core support. Fits nice an snug. End result is that the shroud is held against the radiator, with a bolt on the bottom, and the factory bolt on top.
Thanks. I was wondering why a "direct fit" radiator didn't mean direct fit :-). I checked with other companies too. I found Jegs has the same thing for 309.00. Summit is 299. NPD, Classic Industries, Year One, and The Paddock had stock radiators and aluminum. Only a couple of them had copper 4 row replacement radiators for the 68, but had the bottom brackets only, so not really "replacement" for a 68. Their prices were around 400.00 for the replacements. Plus they wanted shipping costs. They also had aluminum rads, but for much more.
So it's going to be either the Summit or the Jegs unit. No tax for me in Ca and no shipping to pay. There is a 12.00 handling fee.
Does it matter if I use a radiator for an automatic even though I have a manual? Would a rad for an automatic cool less than one for a manual since the trans cooler is taking up some of the overall cooling space? I may go back to an automatic some day, but not sure, so I was considering getting the one for the automatic.
Good deal, I think you'll be happy with the Direct-Fit unit!
Just a note, buy a bottle of Water Wetter (about $7 from your local auto parts store), and also, use distilled water, NOT tap water, to fill your aluminum radiator. You can buy gallon jugs of distilled water at your local grocery store (usually for less that .50 cents each). Running straight distilled water in your engine will run cooler than a 50/50 mix of anti-freeze, but as we know, anti-freeze raises your boiling point...
The reason for distilled water is that regular tap water will cause corrosion in your aluminum radiator. Water Wetter fights corrosion too.
I got the radiator last night and bolted it in, but noticed that the new radtor is not as wide as the original one (by a couple of inches) and actually bolted in diffent holes on the drivers side. No big deal, except that the fan shorud is too wide for this radiator since it was made to fit the wider original rad. So I'll have to figure somthing else out.
Not sure if this was already said, but make sure your head gasket bolts are torqued properly. Most aftermarket gaskets require a retorque after a couple of heat and cool cycles, not to mention the hotter temps will crush the gasket more and loosen up the clamping pressure. Follow the manufacturers torque procedure, it makes a difference.
I have no experience with your brand of radiator. But when I ordered an aluminum radiator from Summit Racing, the same thing happened. The radiator was narrower than the one in the car and was too narrow for the shroud. I sent it back. Then I bought a new 4-core radiator from a seller on Ebay. It was advertised as a Camaro radiator that would fit a Firebird. Same deal, when I received it I found it to be the same dimensions as the aluminum one from Summit. At this point I caved and cut my shroud. Fortunately, it works extremely well.
It appears that Camaro radiators are not as wide as Firebirds. I don't know where you would go to get the proper part. As I said, I gave up ater strike two.
I didn't have any issues with my radiator from Summit, but I bought it several years ago. Who knows, maybe the radiators are made in Taiwan now.
If there's a gap between the edge(s) of the shroud (left and right sides I presume) and the radiator, can you just place some black sticky-back foam weatherstripping between the shroud and the radiator? Maybe the $3/roll stuff from Home Depot. Just don't use the large open cell style weatherstrip, I don't think that will take the heat, but the standard black (something like 3/4" wide, maybe 1/4" thick), would work. You could stack one piece on top of the other if you need to go thicker, because it has a sticky back.
Even without the shroud sealing all around, I would think you could still see if your car runs cooler now. Just make sure there's enough gap from the fan tips to the shroud! I made that mistake once, started the car up, sounded like a machine gun going off as the blades whacked the shroud on one side.
Thanks Steathbird, yes I ended up having to take out enough on the top driver's side and the bottom driver’s side of the shroud to make room for the top inlet and the drain hole. Then I added a bracket to hold the bottom of the shroud and it fit almost perfectly. I have a small gap on the top passenger side where I'll probably fill with the weather strip.
To fill the rad, I used 1 jug of antifreeze, 1 1/2 bottles of water wetter, and filled the rest of the way with distilled water. I don’t need that much antifreeze living in California. I used that formula after reading the red line water wetter paper that Sheri posted above.
The results were amazing. I drove the car for about 30 minutes in city traffic and on the freeway. The temp never went over 160 degrees! Most of the time it stayed at 155. The only time it hit 160 is when I was idling for about 15 minutes. It hit the 160 in about 5 minutes and stayed there, once I took off again it went back down to 155. When I got home and shut it off, it went up to 180.
I tried the whole test again and got the same results. I'm done.
On to the next bug. On the way home the shifter locked up and I had to drive it in second gear all the way. I'll look at that next weekend....
Glad to hear the bird is running cool now. At least one problem is solved before this next one popped up. If it's not one thing, it's another to be worked on.
"An ignorant man thinks he knows everything, a wise man knows he doesn't."
