74_5.0L_Z

Looks good. When I installed mine I lined it up so that the roll bar was parallel to the line of the quarter window. To do that, I had to remove the "little nubbin" that you referred to below the quarter window. To remove it, I just used a hole saw. Because it is a tight fit, you will have to strategically plan your welds. If you are not careful, you will end up with welds that you can't reach. I planned mine so that the main hoop, diagonal, downtubes, strut support, and the tubes that go from the sides of the main hoop to the strut brace could be completely removed from the car for final welding. The following picture shows all of the rear structure installed in the car but not welded to the car. Basically everything in this picture was completely welded together before final installation into the car. I could tip it forward and wrap it out through the passenger side door. Once everything making up the rear structure was completely welded, it was put in place and welded to the car as shown in the second picture. Actually, to complicate things further, I also had the door bars to contend with. So the rear structure was put in place but not welded to the car, then the door bars were placed and partially welded to the main hoop. Then the entire structure was shifted forward to gain access to the remainder of the door bar welds, then finally everything was put in place and welded to the floor and strut towers. This stuff takes careful planning.

After doing about two minutes of web research, I came up with the following: The GT40 heads have a nominal combustion chamber size of 64cc and the early 302 have a nominal combustion chamber size of 58.2 cc. So the downside would be that you would lose compression ratio. The upside is that you would get bigger valves and better flowing ports. Why not go to an aftermarket aluminum head? They are available with small (58cc) combustion chambers and even better flow rates. Currently, I am using the Edelbrock P/N 60379 aluminum heads on mine. They are great heads for a stock bottom end. They were worth 10 mph in the quarter mile over the stock heads. Recently, I upgraded my bottom end to a stroker, so I plan to remove the Edelbrock heads sometime in the future and go with either an AFR185 or the new Ford Z302 head.

I bought some GT-40 heads for my father-in-law's 1968 302 that we put in his 1964 comet convertible. The heads were a straight bolt on. The later model heads utilize a pedestal mount rocker arm, while the older heads use the rail type rocker arms. The newer rocker arm design is much better, but you need to be particlular about which push rods you use. For his application (hydraulic flat tappet cam) we ended up using push rods for a 1982 Mustang. The 1982 Mustang had a hydraulic flat tappet cam and the new style rocker arms. If you are going to use aftermarket rocker arms, then ignore the above, but be sure to get the proper length push rods.

I had my roll bar bent by the guys at ChassisShop where I bought the tubing. They bent it using a die with a 7.0" centerline radius. I asked them about their bending equipment before I generated the drawing. The as received bar was an almost exact match to the drawing. They charged me $80.00 to do the bending, but the quality of the work was worth it.

Cameron, The dimensions on my roll bar gives a VERY tight fit. If the guy bending your bar makes an error tell him to make it on the narrow side. If the bar is any wider than my dimensions, it will not fit. Here is the fit in my car:

Here are the dimensions that I used to construct my main hoop. I believe that the leg length dimensions are a little long (so you will need to trim to fit). A few members have already built roll bars based on these dimensions. I have gotten feedback that the fit was good. http://album.hybridz.org/showphoto.php?photo=2004&ppuser=7833

You don't want a 9" deep sump. If you lower the car, the factory 7.5" deep sump gets pretty close to the ground. I had Kevco racing make me a 6.5" deep front sump pan with dual kickouts, racing gates, and a matching oil pump pickup for about $200.00. I now have 7 quart capacity, better oil control, and an extra inch of ground clearance. The guys at Kevco were great to work with.

OK. So, if you were looking for the lightest, smallest, best flowing muffler that would satisfy scca noise restrictions, what would you use?

This is related I swear: I currently have dual flowmaster 2 chamber mufflers (2.5" in/out). I've been running them for about ten years. The car sounds good and is not overly loud, however with recent engine modifications I feel that the exhaust system is holding me back. The flowmasters are known to be restrictive and this pair was not very well installed. So, I am starting to upgrade the exhaust starting at the back. I am cutting the two crush bent 90 degree bends and the two Flowmaster mufflers off the car and replacing them with mandrel bent 90s and probably a pair of Borla XR-1 mufflers. The main use of this car is autocross, so I am concerned that the Borla XR-1 mufflers may be too loud. I know johnc has experience with these, so I am interested in his opinion. Here are the engine specs: 327 ford stroker 10.5:1 compression 348 rwhp (I expect more after the exhaust modification) I like the Borlas because they are light, compact, and free flowing, but will the Borlas be too loud?

That is how my car looked when I decided to cut the front off and build a tube chassis. It definitely takes a lot of time, effort and skill. If the car is as nice as it looks, the chassis should be sold cheap to someone who wants to undertake the project. It would be a shame to let it get crushed.

Yes, the front frame rails were my reference. The angle that I used was kind of arbitrary. It just worked out that installing the engine at that angle provided the best clearance (at the time the car was originally built). I had to adjust the angle of the differential to match.

If you are starting from scratch, here are two things that I would do differently: 1. Install the engine offset slightly to the passenger (right)side. My engine is centered left to right. This will help even out the left/right balance of the car and reduce the driveshaft angle (the nose of the differential is offset to the right). 2. Move the front crossmember forward ~1". This allows the sump of the oilpan to drop easily behind the crossmember and provides a significant caster increase. You can only really do this if you have camber plates installed. I would keep the front to rear and up and down position the same as I already have it. The driver's side head is 1" from the firewall, and the centerline of the crankshaft is even with the top of the front frame rails (at the front of the engine). Also the engine is installed at an angle of 2.5* (transmission tail lower than the nose of the crankshaft).

Here is a link where I discuss the weight distribution of my car and how it has changed with various modifications. http://forums.hybridz.org/showthread.php?t=92703&highlight=corner+weights

If you search this forum the Ford driveshaft has been discussed several times. A couple of discussions included me. Here is a good link: http://forums.hybridz.org/showthread.php?t=75715&highlight=neapco

Just thought I would add my impressions of the FA slicks at the end of their useful life. When I first installed these I was impressed with their overall grip, but thought the slip angle would take some getting used to. Well, as the tires aged, the slip angles kept growing and the traction kept diminishing. This can be expected with any race tire as it ages. However, these tires go away quickly. All totalled, I got about 20 good runs, 20 mediocre runs, and about 10 runs that were scary as hell because I had no traction. For the price that I paid, I guess they worked well enough (I only paid $100.00 for a set of four). Next season, I will fork out the money for a new set of Hoosier A6 275/35/15 tires. The FA slicks are not in the same league as the Hoosier A6 tires for autocross.

As Dan Juday stated, "there are sevaral factor to consider" when designing the front track width for use with the SubtleZ front fenders. On mine, the front track is 66". I am using the FA slicks which are very short (22.9") mounted on 15x10 wheels. I posted pictures elsewhere to show how they fit and looked on the car. I'll post a few more here: At 66", it looks like I have a little bit of clearance at the front tires, but you need a little wiggle room to allow for suspension motion while the wheels are turned.

My car is just approaching the minimum weight that I am likely to see based on the compromises that I am willing to make and the choices that I made. If I were willing to gut the doors and remove the dash, I could lose about 130 more pounds. If I had constructed the cage of 1.5 x 0.095 tubing rather than 1.625 x 0.120 tubing, I could have saved about 35 lbs. My custom front air dam and hood are heavier than simple fiberglass skins (My air dam with fan installed weighs 20 pounds). Replacing/ removing the glass is worth ~60 pounds. There are many other little gains that are beyond what I am willing to do. If minimum weight is important to you then start with an early 240Z shell. The later 260Z and 280Z shells are heavier. (Jon beat me to it)

My car is pretty stripped. There is no carpet, undercoating, or sound deadening material. The center console, heater/AC, windshield wipers, and radio have all been removed. The stock seats have been replaced with Momo Start2007 fiberglass racing seats which are about 15 lbs lighter than stock. The battery has been replaced with an odessey PC680 which weighs a mere 15 lbs. I do have a pretty extensive cage in the car and an ATL 12 gallon fuel cell with steel can. The car also still has the full dash, all the interior plastic, and all of the glass installed. The car itself without me and fuel weighs 2350 lbs. To me that is pretty light. To get it very much lighter will require me to sacrifice the convenience of roll up windows (I could save 100 pounds by gutting the doors).

My cables are set-up so that they are not adjustable. I used 1/8" multi-stranded cable, thimbles, and crimp connectors. The top is secured to the strut tower next to the spring using a clevis yoke, and the bottom is attached to the sway bar end link. I made the length of my droop limiter such that the spring is slightly loaded at full droop. My wife is out of town and has the camera, so I can't go out and take a picture.

JustOlson asked, "Are you worried about scrapping the frame rail under hard turns? Looks like it was getting close before your switched to the shorter tires." I was a little concerned, but I had no problem while on course. My car doesn't roll nearly as much as it used to. Since then I have added a slightly stiffer front sway bar and droop limited the front suspension. I did have trouble coming on and off the track because there was a slight dip and my frame rails would scrape. Before the next event I plan to raise the front up a little bit by replacing the 450 lb/in springs with 500 lb/in springs. I may then move the 450 lb/in springs to the rear in place of my 425 lb/in springs that are currently installed.

The front leading edge of my rocker panel is 4.25" off the ground, and the rear is 5". The center of my front crossmember is 2.75" off the ground, oil pan is 3", and the lowest point of my exhaust is 2.5". The lowest point however (the leading edge of my frame rail/ subframe connector) is 1.75" from the ground. Loading this thing on and off the trailer this past weekend was fun. I may have to lift it up a little.

I am running the SubtleZ rear quarter panels, and the 23x9.5x15 tires fit well. The YZ rear quarter panels and the correct offset wheel will accommodate the larger 13.5 in wide rear FA slick (In hindsight, I sometimes wish that I had YZ rear Quarters). I bought the 15x10 wheels so that I would have the option of running the FA slick or running the 275/35/15 Hoosier A6 tires. I am willing to bet that my car would be faster on the latter of the two. The deciding factor for me right now is cost. A set of the A6 tires would run me $1100.00 and last for one racing season whether I use them or not (time kills them slowly). This year, I am not able to race as often as I did last year because I am back in school working on my masters degree in Mechanical Engineering, so a set of expensive, time-sensitive tires would be a waste. The used set of FA slicks cost me $108.00 shipped to my door. I figured if they work then great, and if they don't then I'm only out a few dollars. So far, I am quite happy with them.

These are the radial FA tires. I bought directly from Spinwerkes. They were great to deal with, but their web-site definitely needs work.