My friend has a '67 Skylark that someone kind of cloned a GS400. The radiator in it has a curved top inlet. Is this the radiator from the 300? He is looking at a replacement radiator (aluminum) and he says it is the same dimensions as the one on his car but has a straight top hose inlet. Is the only difference in the radiators for the 300 and the 400 just the top inlet shape, or is there a size difference? Does anyone off-hand know the sizes if different? Sorry for the long list of questions but I know nothing about the '67's. Thanks...
My small block 67s ive had all had a Straight upper inlet. My gs400 and numerous others I've seen over the years had the curved top inlet. I replaced mine with a griffin alum with a straight upper inlet
Is there really a difference between the shrouds? Width? Maybe just the shape for the curved hose inlet?
The curved inlet is correct for a '67 GS. They are hard to replace- especially with a generic AL radiator. A lot of '67 cars, including GS cars, did not come with a shroud. They had a dinky top plate, which in my opinion is not really sufficient for a performance car. The small block fan shrouds are quite deep- 4+ inches. The '67 GS400 shroud, by comparison, is very shallow. Only about 2 inches. It's also possible that the fans don't have the same rotational axis, I don't quite remember. At any rate, the small block and big block fan shrouds are definitely quite a bit different. The '67 GS shroud is coveted for swapping 455s into 64-67 cars, so they tend to be rare and expensive. I tried buying a reproduction, but the quality was not really good enough for me, so I ended up making my own shroud.
Thanks for the info and the education. I think his next move is to just run his stock radiator (curved) and get/find a gs400 shroud. His 430 in there currently runs hot at idle and I did a tissue test in front of the radiator and the fan doesn't move any air. When he starts moving, he cools down fairly quickly. Thanks again.
I have a 430 in a 67 with a small block 300 style shroud and the fan seems to fit perfect. Car runs cool too <180 in hot weather with a 4 core stock style rad.
Definitely an air flow issue, maybe a faulty clutch fan. Or fan is too far away from rad. How hot is it at idle? I wouldn't be too concerned unless it's getting over 215*.
Could you post a couple of pictures. I would like to see it. What fan are you using? Looking for some options.
His car runs at like 220 after stopping at idle for less than 5 mins. This is with a 160 stat and the fan is, IMHO too far from the radiator. He has no clutch and a cheap flex fan. I told him to get a good fan and let's get the shroud on and spaced correctly. He had the radiator checked out and it was good. The motor is a unknown rebuilt (?)430 with a suspected spun bearing. We are getting ready to put a fresh (built by us) mild 455. Just trying to prevent any problems
Maybe the old 430 has a cracked head. That was a common problem, external cracks between the valve springs.
Possible. The new engine has 455 heads and everything was magnafluxed and checked out. The core engine stayed standard on the bearings and the bores! Super clean engine.
How many blades on fan? Get a shroud. Proper depth of fan into shroud... Aluminum radiator with appropriate core size and with no less than 1" tubes. Theres quite a few post about aluminum radiators.. Just do a search... When looking at all radiators make sure the inlet and outlet are on the correct sides and for your hose hookups...Make sure the rad nozzles are same size of your hoses... I just purchased the one below for my 350 Suncoupe after a friend recommended it...He's driving a 66 Skylark so his may be the same as your friend needs. http://www.jegs.com/webapp/wcs/stor...&submodel=&engine=&Nrpp=&No=&persistYmm=false
If it overheats at 2500 RPM on the freeway, you need a better radiator. Overheating at idle typically means other things. Before replacing a (probably perfectly functional and good looking) Harrison copper/brass radiator, I would look at: 1. Ignition Timing. You want 25-30* of spark advance at idle to run cool. Set the initial timing at 10-14 degrees, and connect your (properly specced and fully functional) Vacuum Advance Control to full manifold vacuum for another 16 degrees. 2. Thermostatic Fan Clutch. I recommend Hayden 2747. "Heavy Duty". $42.97 on Summit Racing. You want the clutch real close to the radiator, for the valve to operate well. Annoyingly close. 1/2" or so. 3. Fixed-pitch steel fan. Most Buick guys swear by the 7-bladed 18" HD Buick OEM fans, use one if you can find one. I am running a 6-bladed 18" fan I found on Summit Racing, seems fine to me. 4. Fan shroud. You want a shroud whose "rectangle" covers the entire radiator core, and whose "circle" fits tightly around the fan. My homemade shroud has a 19" opening. 5. Shroud-Fan Spacing. You want the fan to be 40-50% inside the shroud. You can shim the fan towards the radiator by shimming between the water pump pulley and the fan clutch. You can shim the fan away from the radiator by shimming between the fan and the clutch. 6. Water Pump Pulley. Given a constant accessory belt speed, a small pulley will spin faster than a big one. An oversized water pump pulley will slow down both your water pump and your fan- double bad for idle cooling.
I agree.....if the fan is too far away, he's not pulling air THROUGH the radiator. It's pulling a lot of air from around the rad. He can try his flex fan and just use the proper fan spacer to get the fan closer and see it it improves. I get great performance with either a clutch fan or the non-clutch 7 blade fans and NO shroud on my 66's. Fan just needs to be spaced properly, within an inch or so. I've modified 300 cid shrouds to fit the 425 in my 66 GS. Had to turn it upside down and trim about an inch from the fan opening to make it thinner. If Anthony say's it works on his 67, it might be worth a try. The repo 67 GS shrouds are/were made by Kirban Performance and sold through resto suppliers like the Parts Place, Year One, Cars, etc. As Michael sad, the repos are fiberglass and need some finish work to look nice.
In my opinion those flex fans are junk, they don't move air just churn it! Had one that came with a 67 Special, replaced it with stock 7 blade and lowered idle temperature by 10 degrees. Do need a good shroud with proper spacing too.
Am very pleased wth my Dennis Kirban reproduction shroud. Took some work. Installed,it's indistinguishable from oem.
This is the best one I have on my phone. It looks like a 300 style shroud that was trimmed to be thinner. The fan looks like a stock-type replacement with a centrifugal clutch and a small water pump pulley. It's pretty close to the rad too but I forget exactly how much. So far it works.
Thank you! That's what I was looking for. Was always told I needed the 67 GS400 shroud and the 300 shroud wouldn't work. Of all the things to not try to make work, this was it. I've done other things to my other car(GN) that people said you could not do(a lot more complicated than this), and it never occurred to me to try this. Now to trim down a perfect 300 fan shroud!
I bought the car like this. I assume it's a 300 shroud because it sure looks like one, and that's what this car probably had in it prior to the 430. But before you cut a shroud maybe do some measuring just to make sure! (I also have a GN.)
