First, let me start by saying I have read the sticky on Aluminum Radiators and related topics the last 2 days since I joined the forum. My eyes and mind are tired! also an overthinker, so need some help determining if I am going down the right path with the right part. Just a little background, I am the new owner of a 1971 Stingray handed down to me by my stepdad who has been the only owner. Paid $5500 cash in '71, just found the sales paperwork the other day. Very cool.
I am a novice in the garage I would say, so please take it easy on me if I say something stupid! But I can follow direction & am learning from my stepdad (75yr old) and my uncle (81yr). Uncle has built 60 and 61 Corvettes .
Here is what I know about my Corvette.

• 71 Stingray
• Small Block 350
• Automatic (3 Speed)
• TH400 Transmission
• Had AC at one time, not worked since I have known of the car. Always driving with tops out anyway so have not attempted to fix.
• GymKhana Suspension

I will start out at the beginning but try to be concise...Car sat in the garage probably 5-6 years not being driven. Stepdad Took it to get a tuneup and had been running fine on local drives. Drove it to local cruises last year and this year... started noticing earlier this year on highway it would not shift into 3. 1,2 fine. Stayed at 3-3500 RPM around 50-55 mph, would never drop down until I let off the accelerator. Think we possibly found issue with the Vacuum modulator? The modulator we pulled off had transmission fluid coming out the other side. We were getting ready to go test the replacement and when we backed out off the lift the radiator let loose. Original Radiator on the car.
I am a mainly local cruiser, weekend driver and have determined I am going to go with the Champion Aluminum, but need to determine the correct one. I think it is the one in the photos. Can anyone confirm. . Also the overthinker in me is not sure about saddle mount or bracket mount? Just wondering what needs to be done to make sure it is in correctly. If anyone has experience with this and can help a newbie (with some experienced help) out it Would be much appreciated
Here is what I am looking at.




If more info is need please let me know.

Other issues which I can post separately if needed - Oil pressure, clock and temp Temp gauge also not operating.

Thanks everyone

 

That is not the correct radiator for a base 350 SBC Corvette unless automatics are different. My '71 is a 4-speed. . It shouldn't have the radiator cap on it if its the same as the manual cars. The cap is on the overflow tank on the drinkers side. You should already have an aluminum radiator if still factory stock. Go with a DeWitts direct replacement. They are a work of art and fit perfectly. I can post pictures of my stock 350 1971 setup if you want. If you are going to dive deep into repairs get the AIM (Assembly instruction manual) It's what the factory used to build them on the assembly line and is a great resource of how things go together and many adjustment procedures for various systems.

 

There’s a very similar thread going on right now about a th400 not shifting into third. Big takeaways, yes the vacuum modulator plays a big role in shifting to third, replace it because it’s easy. If no improvement you could pull the pan and inspect the valve body and 2-3 accumulator, BUT since you can get it to shift into third the valve body and 2-3 accumulator are probably working.
if the vac mod doesn’t help then it’s probably slipping in and out of third. Let off accelerator, no load, shifts to third, as soon as you get back into it, it slips/can’t maintain.

 

I'll see if I can find that thread. I am not sure its getting to 3rd? Don't really feel it getting there and when I let off accel the RPMs go down a bit but to maintain 55 its running about 3-3500rpm? Unfortunately gotta get the radiator replaced before I will be able to test that out. Thanks for the help

 

I have done a lot of research the last few days, still confusing!. However automatics, w A/C are different than Manuals. Also has integrated Trans cooler. Dewitt's not really in my budget at the moment unfortunately. I only drive it maybe couple hundred miles a year locally... so not trying to break the bank. I appreciate the response and will look into the AIM, sounds like a good resource.

 

I'll look in my AIM and scan the radiator pages for automatics for you. Just try and stay away from any radiator that has the tanks epoxied on.

 

I looked through my AIM but can't find anything that shows the radiator on a base 350 with automatic transmission, at least I can't find it. I'll keep looking but in the mean time this is what my base 350 with a 4-speed radiator setup looks like. This is stock except for the new radiator which is a direct fit and compared to the original it's exactly the same.

Expansion tank with cap


My DeWitts direct fit radiator


Engine compartment view


Another view


Right hand side tank and lower hose


When you do replace it make sure you install all the seals required as this greatly helps the cooling capacity.