I've taken the airbox assy. out of my car, and I'm going to weld a plate across that area. But before I do, I have a couple questions on that, and some on welding the factory seams and on a rollcage: 1) For those who've done this, did you grind/cut out that bulge where the blower sits (see picture)? It's taking up empty space, so I want to remove it and have a flat firewall in that area. 2) What gauge metal should I use to weld onto that area, or what gauge is the stock firewall? 3) Would it be worth it to tack/full weld along the seams like the Jap Camaro had done to it? Would this make the car any stronger or keep it together longer? (I plan on putting in a 6 pt rollcage and SFCs also.) 4) Since I said rollcage... what size tubing to most of you use, and what thickness? I'm not doing sanctioned drag/road racing, just doing it for my own use and to help strengthen the car. Thanks.

The area where it drops down on the right side is also a water draining channel from the cowl and which empties out behind the fender. You'd probably want to either just cover the openings, or install in interior vent from a non-AC car to the inside opening.

Ok thanks, that answers 1. I looked at it closer, and you're right, that's the drain area. Anyone know about the other three questions?

Edit: I looked around and found that most companies make them out of 1.75" x 0.134" when going with mild steel. So I guess I'll use that. I'll probably buy a caliper (been needing to buy one, just haven't yet) and measure the thickness of the firewall, so that's no problem.

Remaining question, since I'm going to be taking the black stuff off the rest of the weld joints (it's falling off anyways) should I tack along the factory "weld" seams or not?

I have to ask… why the hell would you want to put a roll cage in a car if you’re not required by some sanctioning body? There is almost no good way to do it without limiting access to the interior and if you’re just looking to strengthen the chassis then there are loads of ways to do it that are not nearly as annoying.

As far as “if there was no sanctioning body and I really had a good reason for it,” it would depend on what that good reason was. If I was planning on using it as a “stunt car” that is likely to be rolled… I would use 1.75x.120” (next thicker wall that I can find, probably .134”) DOM, and if I seriously expected it to end up on it’s roof I might even consider making the main hoop out of 2”. Of course, I would seriously reconsider using an f-body for anything that is likely to end up that way since the roof line is so short that there is almost no way that I could put all the main bars over the height of my head to really protect me unless I actually cut the floor out and moved it down significantly.

If this was a road race rally type thing then I would probably look at 1.75” .095” or 1-5/8” .134”… of course, at that point we’re getting into the “this doesn’t make sense to do range again and I’d probably just build it to the most likely standards that I’m going to be reqired to meet with the car, 1.75x.134” for a 6pt roll bar or for a full roll cage for road racing use or 1-5/8 x .134” for a roll cage that would meet nhra/ihra standards.

FWIW, if the car it totally disassembled, I’d weld any seem that I could get to/have time to.

Hey buddy, calm down. If you want to tell me not to use a bar, then give me other options.

My reasoning is: it's a t-top car. I'll be putting in SFCs, and I thought that a bar would help keep things tied together as well. Plus, the way I'd make it would not limit getting into the front seats, and as I don't carry people in back often, they can crawl across the bar.

So how would you go about strengthening the body besides SFCs alone? I respect everybodys opinion, but it doesn't do me any good for you to get on my back about a rollbar and tell me there are "loads of ways" to strengthen our cars, and yet not list your thoughts. I can't think of anything else except SFCs and a rollbar/cage. It's a unibody car... what else is there?

yea well i did the same ****ing thing...i have sfc and a roll cage..and yea my car is set up for road racing ...i like the look of a cage i can also run harnessis if i whant..

I'm wondering the same thing since i have my car completely stripped and I have a welder and i can lay a decent bead.

I would definitely weld up all seams you can get access to, just be careful not to put too much heat into one area at a time so you don't warp the metal.

As for adding more strength to the car, I just had to patch a hole in the drivers floor of the car and I cut out the "box section" that the front of the seat mounts to. Well when I did that, and removed the section of floor needing replacement I noticed that this part connects the frame along the transmission tunnel to the rocker panel. What I did was take a section of box tubing that would fit inside this section and welded it to the trans. tunnel, the rocker panel and along the floor before welding the seat support back in. It is a T-top car and I got in and jumped up and down (I weigh about 230lbs.) and the floor or car did not flex once.
It's a great place to add some strength (also a great place to hide it and not mess up the stock appearance!! Worked out great for me. I am thinking about doing the rest of the seat supports, passenger side should be interesting though.

I cut off the lip around where the blower sits... you can't get a flat firewall otherwise... not hard to cut... just cut a square around it and take it all off...

As far as the metal goes I used 25 gauge metal to make my cover... then I used screws and rivets all the way around... works good for me...