NC rust is just like PA rust. Throw in some chlorides from road salt for good rust acceleration.

I would love to get a hold of a corvette and take a look. I would be interested to see how they changed the designs over the years too.

I really do appreciate the concern. I maybe a bit stubborn, but I will listen. I do believe my floor pan job is by far excellent, and the only area that anybody is concerned with is the pillar??? (and not the bottom hole? - I think I threw in a picture there). I did install sub frame connectors, so tensile force loads on this location should be minimized due to the force path through the connectors in addition to the uni-body. For the record, I don't like doing epoxy as I would much rather have no rust at all. Given the state of the economy, I truly doubt that this is a $50 welding job. Maybe if everything was set up, but you couldn't even justify the gas for the welder to come to the car, or the time to take off the body panels if the car was delivered to the welder.

Did a quick look at West System properties:

1) Yield strength in compression is 11,500 psi. Not like failure would occur in compression unless maybe a high G accident causing the weight of the roof and windshield to crush the epoxy.

2) Yield strength in tension is 7,300 psi. Assuming 1 in^2 of the stuff and two columns, it would take 14,000 lbs to separate the windshield from the dash. In all actuality, I would expect the epoxy to part from the POR-15 before the epoxy cracks. Steel is roughly 5 times stronger.

3) Youngs Modulus is 460,000 psi with a 5% strain before failure vs steel's 29,000,000 with approximately 14% strain before failure. According to these numbers, technically the steel should be harder, no? As long as the strain is not exceeded, the epoxy should give more than the steel.

Let me know what you think.

regardless of the strength of the epoxy the connection to the other body component is the weak link.

when you weld in a panel its becoming a piece of the original, not attached to it. West Sys. is good stuff but even if you cant afford to pay a welder you can buy a cheap mig gas welder at Harbor Frt. & get away with that - west system isn't cheap stuff & likely when you hit the first bump in the road you'll crack at the weak points then you'll be doing it all over again. For me thats worse. On boats epoxy laminates of wood with vacuum bagged epoxy are extremely strong but thats because the epoxy is drawn into the wood fiber & becomes "one" with the layers thus creating the strength, kind of like welding.
Good luck with the project.

Well call me old fashioned but I'm still skeptical!

I have messed around with different epoxies for different uses and they're great. I patched the cracked block in an old Oliver farm tractor probably 10 years ago for my dad. I drilled the ends of the crack, grooved it a little and coated it with epoxy. It's still holding water, and it's survived countless heating/ cooling cycles without cracking or popping off (my big fear).
But I'm still afraid that with the properties the epoxy and steel being different it'll still fail. I think if the materials were up to the task that 3M or PPG or someone would be selling it as a structural repair adhesive now, but they won't take the liability of it failing. Like I said maybe I'm just an old fart but I don't see a no weld solution anytime in the near future.
Old Vettes are a good example- they take a steel frame and mount a fiberglass body on it. But! guess what else is steel- the window frame and the hinge pillars. The firewall is glass, bonded to the steel but they couldn't build them entirely out of plastic. I'm not sure what the latest versions are like, but I'll bet there's still steel in there somewhere.
Here's a good site showing what I'm referring to, (Sorry Mr. Moparts for posting a Chevy link)!
http://www.corvette-restoration.com/restoration/corvette_restoration_updates_all.htm
Scroll down to the posts from Sept. 2007 and check them out- notice the "birdcage" as he refers to it. It's pretty badly rusted, but he years it all apart and welds in new metal. Now that's the correct repair for repairing the car from a collector's point of view but it also says that even the factory wouldn't use fiberglass for key areas- and that's the exact same area where the crack is on your car!
It might be a hassle to get welding done, unless you can find a trailer and load it up. Take it to a couple shops, show them what you have, ask them for a time and material quote- there are enough small shops around here that do it (and I'm in the boonies). BUt really you're not asking them to fit and repair anything big. That would be cutting back on each side of the crack maybe a half an inch, fitting a patch and welding it in. I can tell from your other work you'd be skilled enough to do the finishing, you could probably even cut out and fit the patch- all they'd have to do is weld it in. And if you find a skilled guiy he might be able to fab a piece to fix the plenum that would make you life easier fixing that.
If you do go with what you've done, keep us posted. Not to be a jerk and say "Told you so", but I'm always looking for stuff that might work. My 69 is going to take some major attention from the AMD catalog to get where you're almost at now, but it's my baby. If it takes me 5 years, OK, so? But other than Fusor for the bottoms of the quarters it's mig time for me!

You can take sheets of fiberglass and resin and patch a complete quarter if you want... even make the quarter out of it like a hood, door and so on. In the end it's a temporary fix.

Basically a bandaid and eventually your going to have to fix it right. Just like the aluminum cans and such I have replaced while putting quarters on a a project car someone didn't repair correctly years ago.

My truck was bubbling in the rocker last fall, garage was full and no time to fix it right. So I used fiberglass and epoxied it before winter... after winter, it was rusting around where I fixed. See where I'm going here? If you think por-15 is gona save the rest, your going to end up disappointed.

No matter how high tech it seems, replacing metal with metal and welding is the only way to do it right.

I will definitely keep you guys posted. I tell you what. My long term plan is to take the car to a welder and put on new quarter skins in prep for an uber awesome paint job. I will put this on the to do list when that gets done. In the mean time, this is better than doing nothing. Any concern with the bottom patch? Is there a place to buy an air box plenum bottom? Is that the right lingo?

I'm not sure the proper term, I'd call it the lower cowl? I don't see anything that looks close in the AMD catalog, you'll probably have to find a used one and cut it out. If you're in CA (like your tag says) ot even NC you should be able to find a donor, for that particular piece I'd bet it would be the same for Dodge or Plymouth and even 4 doors? Maybe someone who knows more will chime in. I'd measure yours up close and head out to the junk yards, I'd bet that 71-74 would fit and I'd be looking at 75-76 too, if you happen to stumble across them. I keep a couple pics on my phone so I don't need to rely on my memory, and write the measurements down. The worst part will be tearing it apart enough to see, but once you find one the yard might even cut it out for you- if not it's time for a hole saw in a cordless drill and a battery sawzall!

you know if you cant find the panel or piece you need you can always form it from sheet metal. All of the patches on my Datsun project I hand formed cuz there isn't a AMD catalog for Datsun's .

The good part of that was I learned how to hand form metal, wasn't too hard, here's a piece with odd curves that I made...





hard to see but other side of radiator under battery tray is that patch, no really good after pic's..


the point is you dont have to only buy patch panels, time & effort will solve all, good luck!

i would hate to be the one who
has to chiesel that crap off to fix it properly..

The part you need for the air box is part of the firwall. I have some.