I decided to clean off some of the grease, undercoating tar and rust and then paint the engine bay on my 79 while I have engine out, and I'm surprised by some of the frame welds.

I've driven this car on and off since I bought it in 2013, but have never had a reason to look at anything too closely before. However, the weld quality seems much worse than my 70s Chevy trucks. For others with C3 cars, does this amount of spatter and generally sloppy welding seem factory? Or is it possibly the result of a cheap collision repair sometime in the past?

I've had the car aligned in the past and never got any complaints from the alignment shop, so I assume the frame is mostly straight. I'm going to grind out and re-weld the cracks and probably not worry about the rest of the mess, since this is going to be a budget driver and you won't be able to see it once the car is back together.

However, I'm curious what others think about how this compares to frames on other C3 cars. I'm just a self-taught hack with a cheap MIG, and I think I could have done a better job than whoever last welded on this frame...

 

Yup
my 79 the same and have the cuts to prove it from lengths of mig wire sticking out too…
character…
my guess is assembly line hot migs..glue it and go..pretty robust system

 

Those welds are very typical of every frame built in that era. Assembly line work, quickly done, strong as can be and not cosmetically important because customers buying new cars didn't generally inspect frame welds.
So, while they may not be pretty, they certainly do the job.

 

Edit - this first part was a reply to another poster who suggested the photos were my work, and that I should buy a better machine and "learn to weld". That post has been deleted, but I'm leaving my reply for context:

Thanks for all the replies. This is certainly not my work, but when I weld I'm working for free. So I spend however long it takes to make it look nice. I haven't done any welding on this car, and don't plan to other than fixing a few cracks I've found.

The whole front of the car is covered in welds like this, and while they're not what I'm used to seeing from production welding (I work in aerospace) I agree they are perfectly strong and will do the job. I guess I'm like the typical 1970s GM customer, because I also won't be looking at the welds once it has paint on it and the engine is back in. Thanks again for the replies!

 

Are you going to gusset and brace?

 

Not now, unfortunately. I started taking the car apart in 2019 with the intent of removing the body and doing a full restoration, and made pretty good progress for about 4 months. But I realized without an indoor space to work and store parts I would quickly be in over my head doing a body off restoration in my back yard, and I lost motivation to work on it at all

3 years later I found myself thinking about selling the car in pieces, which I really don't want to do. So the plan at this point is to make the chassis as nice as I can with a couple weekends of work, then put the car back together and drive it for awhile. Once it runs, I'm sure I'll never think about selling it again! I have a 396 SBC on a stand ready to go in, all the control arms, steering, and brake components are sitting in the back of the car rebuilt and ready to go, Vansteel springs and shocks, etc. Just needs assembly.

I can't make myself install all the clean new parts I spent so much effort restoring onto a greasy tar covered frame, but the reality is I don't have time and space to do a full restoration either. So I'm just going to make it nice enough to be a fun driver I can be somewhat proud of, enjoy it for a few years, and when I move out of CA and build my dream shop then I'll restore it again properly.

 

There is something called the Chevy Power Manual which talks about chassis prep. Wish I had seen it when I had my frame out. Regardless, 50 years of abuse and sticky tires and more torque and the factory welds still hold

 

Yes, as others have agreed, the original welding on the cars was pitiful. But it worked. On my 77, and now on the 69.....all that weld splatter is ground of, all the bad welds re-welded properly, and I am welding all the spaces between the poor welds....as the Chevy Power book details. I may also add some of the gussets they recommend. Of course, I am not racing the car, and never will, so I am just doing because the frame is sitting on a dolly in my garage....completely blasted and bare,....so why not?

I will also add that while most folks see a "frame" as a hidden, irrelevant piece of the car, in terms of cosmetic appearance......I see it as just another part of the car that should look as nice as the best parts. I see guys restoring seriously pitted frames, and just using POR15 over the top, leaving weld spatter, and junk welds. It may be original, but it looks like crap. I fix it.

 

I scrolled down just to write this.

Duntov has a PDF of the Corvette section on their website:
https://www.duntovmotors.com/Corvett...wer%20Book.pdf
Check under Tech Tips if the direct link doesn't work.
https://www.duntovmotors.com

I picked up a copy on eBay. It's a nifty read.

 

IMHO - Many of those welds are truly CRAP, but because the amount of weld area, and the loads the parts see, it does work. We all know that assembly line labor in the 1970's was NOT the greatest - while some workers took their job seriously and did very nice work - some absolutely DID NOT !

The cheapest steel has a strength of about 30,000 Pounds/sq inch. Typical low cost weld rod / wire has a strength about twice that. You don't need a ton of good weld area to get to the kind of strength you need for the car to work properly.

IMHO - weld up any cracks, and if you see areas where the welding is really bad - grind it down a bit, and re-weld it, but you don't need to redo every weld on the car. Now - if a big Block and drag slicks are in your future - or if you intend to run the car in an autocross - then you should probably consider doing a bit more re-welding, and consider adding in some gusseting / reinforcement of certain areas.

 

How in the world did you manage to clean the frame like this?

 

We see these cars as something to preserve for generations, the original design concept was 15 years of use and into the landfill. The engineers designed the frames to allow for these quality of welds. I’m a awfull welder but can exceed this quality.

 

With a wire wheel and a lot of patience.

I removed the hood and everything in the engine bay, masked the body/windshield with plastic and moving blankets, and spent a couple days first powerwashing and then cleaning with the grinder/wire wheel.
Then phosphoric acid etch, prime, and paint. I was just using spray cans becuase I dont want the overspray from the HVLP going everywhere. It'll be good enough for my daily driver

 

On my 71 I did the same cleaning and was kind of shocked how bad the welding was. I ground of all the slag and then mig welded everything as needed. Tip from a pro welder friend of mine. Get some scarp metal the same thickness as what you are going to weld and practice welding both horizontal and vertical. Helps with welding style and getting the mig dialed in heat wise and wire speed wise.