When you click on links to various merchants on this site and make a purchase, this can result in this site earning a commission. Affiliate programs and affiliations include, but are not limited to, the eBay Partner Network.
I've removed my radiator in preparation for body separation from the frame. The existing metal around the bottom of the frame is rusted, as you can see in the pics. Both sides on the bottom of the frame are rusted. These frames are pretty expensive for a '69 4-speed SBC - I'm seeing around $400+. I'm already spending a small fortune on this restoration, so looking to save where I can, but I don't want to save at the expense of a questionable repair. I seems solid enough, even with the rust, but I honestly think it may have to be replaced.
My question is two-fold...
Is it worth repairing and repainting to be re-used, or should it be replaced? OR;
Would it be more ideal to replace the original brass radiator with something aluminum (like a direct fit Dewitts)? I'm building a 383 @10.4:1 compression or so. Never had any overheating issues with the original motor, but will the original radiator be able to handle the extra heat from a moderate 383 stroker motor, and does an aftermarket unit like a Dewitts use the stock radiator frame? Is there a replacement radiator on the market that also has a frame that is direct bolt for an early C3 Corvette?
I did browse the sticky on aluminum radiators, BTW. Good information...
Last edited by Corvette-ZL1; Jun 27, 2022 at 06:32 PM.
it is not just a rad support. it is a nose support. and it is trashed. it could be repaired. but replacing with a full-width opening rad support makes the most sense. and the nose should be supported where the rad support came out. a 2x4 cut to the right length should do the trick.
About 5 years ago I was rebuilding my engine. Found my rad support in similar condition. being poor but also being a fairly good welder. I choose to cut out the bad metal and make up replacement panels and weld them in. As I cut away bad metal, I found the rust was actually much worse than it originally appeared. Yes mine looked much like yours. Seems they rust from the inside out. So you can expect that your support is very likely much worse on the inside than what you see on the outside.
I did repair mine. Basically replacing both sides and most of the bottom. Making up several (as in many, many) repair patches and welding them in one at a time while clamping the frame in place to prevent twisting. It turned into a huge job. No one really sees it unless they are under the car. So I wasn't concerned that it looks like a patchwork quilt. My end result is one strong heavy duty rad support that isn't pretty. Cost me nothing but price of paint to paint it. But if I were to bill out time to repair it. Could buy 2 or 3 of those 400 dollar units.
As per radiator. My car never had overheating issues with the stock engine and rad. But bump up the power!
Go with the Aluminium rad. Dewitts are considered among the very best. And they fit your rad support correctly.
body separation from frame. buy a welder. put fixing it yourself on the back burner for after you picked up a mig welder and learned how to use it. gonna be more spots that need a little new metal. even if it is just welding new mount nuts into #2 and 3. or at least put it aside and find out if the middle 4 mounts are gonna cone unbolted. i probably said, but stick something under the nose to take the weight. might even be best to put the rad support back with a couple bolts a side.
Thanks for the input, all. I guess I'll have to just bite the bullet and purchase yet another part. Does the saying about a boat being a hole in the water that you throw money into apply to classic Corvettes?
If I decide to stick with my original brass radiator, should it be sufficient for a moderate (approx 425-450 HP) 10.4:1 compression 383 (actually 385) stroker?
Last edited by Corvette-ZL1; Jun 28, 2022 at 10:38 AM.
2020 Corvette of the Year Finalist (performance mods)
2019 C3 of Year Winner (performance mods)
2016 C3 of Year Finalist
Originally Posted by Corvette-ZL1
Thanks for the input, all. I guess I'll have to just bite the bullet and purchase yet another part. Does the saying about a boat being a hole in the water that you throw money into apply to classic Corvettes?
If I decide to stick with my original brass radiator, should it be sufficient for a moderate (approx 425-450 HP) 10.4:1 compression 383 (actually 385) stroker?
Try it first but i doubt it. Especially if you sit in traffic on a hot day. It might be fine on the highway if all the seals are in the right places
Thanks for the input, all. I guess I'll have to just bite the bullet and purchase yet another part. Does the saying about a boat being a hole in the water that you throw money into apply to classic Corvettes?
I was into boats for years prior too my Corvette, so it was an easy finical transition for me. LOL
I would stick with an aluminum radiator and there are other options. I have a BeCool aluminum radiator that has worked great for me and my 12.25-1 Compression ratio 427. I also have two SPAL 11" fans connected to a PWM Electric Fan Controller that starts the fans up at 50% speed and slowly ramps the speed up IF the engine needs it to. Having a good radiator shroud with the electric fans is critical for a cool running Corvette. I am also a big believer in the Red Line Water Wetter additive in the coolant. Be sure not to use too much anti-freeze in the coolant mixture. If you live in southern California you could get away with the 70% water 30% anti-freeze which lets the system get rid of heat better than the 50/50 mixture used in most areas. The higher the water content of the coolant is better for getting rid of the heat. That and a good radiator cap that holds pressure. Be sure that your radiator is well sealed so all the air goes through it instead of getting around the radiator, the seals in the engine compartment are very important on this issue.
Try it first but i doubt it. Especially if you sit in traffic on a hot day. It might be fine on the highway if all the seals are in the right places
I'm hoping that it would work ok if passes a pressure test. I mean, these radiators were designed for 350 small blocks with 10:1 and 11:1 compression ratios. Anything with compression ratios that high are going to generate more heat.
Last edited by Corvette-ZL1; Jun 28, 2022 at 06:33 PM.
I would stick with an aluminum radiator and there are other options. I have a BeCool aluminum radiator that has worked great for me and my 12.25-1 Compression ratio 427. I also have two SPAL 11" fans connected to a PWM Electric Fan Controller that starts the fans up at 50% speed and slowly ramps the speed up IF the engine needs it to. Having a good radiator shroud with the electric fans is critical for a cool running Corvette. I am also a big believer in the Red Line Water Wetter additive in the coolant. Be sure not to use too much anti-freeze in the coolant mixture. If you live in southern California you could get away with the 70% water 30% anti-freeze which lets the system get rid of heat better than the 50/50 mixture used in most areas. The higher the water content of the coolant is better for getting rid of the heat. That and a good radiator cap that holds pressure. Be sure that your radiator is well sealed so all the air goes through it instead of getting around the radiator, the seals in the engine compartment are very important on this issue.
Is that a 427 BB or stroked small block? I've seen the BeCool radiators on Summit, but not many reviews. They are more reasonable than the Dewitts, but was yours a direct fit, as the Dewitts are? I'd really like direct fit, as I have enough work on this car piling up as it is. It's crazy that the stock radiator can't handle a 383 well, as these were originally designed for 350 small blocks with 10:1 and 11:1 compression ratios for the 350/300 and 350/350, respectively.
2020 Corvette of the Year Finalist (performance mods)
2019 C3 of Year Winner (performance mods)
2016 C3 of Year Finalist
but they were putting out 100 less horse than what you have. Horsepower makes heat. You've got a bored and stroked 350 that is a 383 now. Like I said, go with what you got and see how it goes. Its not costing you anything to try it out. I had a 327 that was about 450 HP at the crank and it would get really hot in traffic until I pout in a big block radiator and I had an electric fan and a tight cowl so it had max cooling at low rpm. If your radiator is as big as a big block radiator then you should be able to use it....I think 69 still had a small block and a big block/ small block auto trans radiator like they did in 68
The original 69 4 speed, no air cars used a Harrison stacked aluminum rad.
That is what you have.
I used the stacked B-Cool replacement for years and 2 motors with no heating issues here in Florida.
If you get a rad support for a wider rad, you will also need the rad mounts and cushions. The shroud is also different and expensive.
I tried the stock rad in mine. didn't work. Replacement new stock rad. Didn't work. 2 core aluminium rad. Better, but still not good enough on a hot day stuck in traffic. 4 core Aluminium rad for a big block car.
My car is happy now.
Just my 2 cents.
if trying to stay with current rad, i would weld or have welded the orig rad support. last thing you wanna do is buy a new 3 or 400 buck small radiator rad support then find out you need more cooling than you have. you can usually find a 100 buck harbor freight welder for 50 bucks. the bad spots on the rad support are in a place where your ugly first ever welds will not show at all...
if trying to stay with current rad, i would weld or have welded the orig rad support. last thing you wanna do is buy a new 3 or 400 buck small radiator rad support then find out you need more cooling than you have. you can usually find a 100 buck harbor freight welder for 50 bucks. the bad spots on the rad support are in a place where your ugly first ever welds will not show at all...
Unless you get a direct fit replacement such as Dewitt's, from what I understand from research and reviews can use the radiator frame/support without modification.
Last edited by Corvette-ZL1; Jun 29, 2022 at 05:10 PM.
here is the diff. you could probably cut the sheet metal sides out of your support to match the bigger hole in the AC and BB and newer rad support. and redo the mounts for the different radiator. but this is why i feel you should make do with a patch job on your support until you commit to a bigger rad and electric fans and shroud from a C5.
'69 Radiator Support Rusted....
