I hate to say it, but you seem to be overanalyzing things. Really, do you expect to get an engineering report on a set of aftermarket wheels when you buy them? Here we can say there is a safety concern since most are obviously lighter than the factory steel. The same can be said of aftermarket brakes, custom steering wheels, four-link rear suspensions, fiberglass leaf springs, and the list goes on. You are not going to get an engineering report on any of it. You actually have an advantage being an engineer because you can potentially do the structural analysis of a B-Body Mopar yourself. Frankly, most aftermarket mods begin with an idea and are tested in the field by doing, and gain acceptance as the modification proves successful. You state you trust nobody and want to see the math. When it comes down to it, personally, I think it is misguided to trust the numbers, even if such a study could be made. A bunch of calculations based on sometimes bogus or misguided assumptions is far inferior to a design proven in the field, no matter what it is.
Wants Mustang Wheels
I have a '68 Road Runner that I'm rebuilding. It currently has all the stock suspension components. I was wondering about using Mustang-style wheels on my car. There are several 17- and 18-inch rim combos in 8.5- to 10.5-inch widths. I saw a Road Runner on ebay that had a set of 17s on it, and the wheels had Cobra emblems on them. Have you used any of these or have any info if they would work? Do you have suggestions on back spacing? I would like to use 8.5-inch in front, and 10.5-inch in the rear.Tim Secrist Mentone, IN
You can go with the Mustang wheels, but the problem is the backspacing. Modern cars have very shallow rims with minimal "dish," and the Mustang rims are no exception. Mopars like your Road Runner were designed for rims that were near centerline for offset, and typically had plenty of wheelwell to move the wheel outward. Most aftermarket wide wheels from back in the day were deep-dish designs for that reason, and that was an important part of the aesthetic of the car, giving a sense of depth and width to the rolling stock. When modern wheels with high backspacing are used, the result looks flat, and the car loses character. guys that run late-model wheels find wheel spacers are needed to move the tire out and centered in the wheelwell.
Getting Even More Power
I have a two-part question I hope you can help me with. First, I'm planning an intake and carburetor change on my 440 to ease with fuel system and nitrous set up to hopefully gain some more power. The current engine combination is a stock 440, bored .040-over with forged pistons giving an 11.0:1 final compression ratio. The engine has a stock stroke forged crankshaft and forged-steel connecting rods. The heads are Edelbrock Performer RPMs with extensive porting and 2.20-inch intake and 1.80-inch exhaust valves. Flow numbers on the SuperFlow bench at 28-inch water and 0.600-inch valve lift were 340-cfm intake and 260-cfm exhaust.
The engine uses Comp Pro Magnum roller rockers and a D. Elgin Racing Cams flat-tappet hydraulic stick with 0.540-inch gross lift on intake and exhaust, 254-degrees intake and 259-degrees exhaust duration at 0.050-inch. The current intake manifold and carburetor is an Offenhauser dual four-barrel manifold with two Carter AFB 650-cfm carbs. This combination made peak numbers on a SuperFlow dyno of 543 hp at 6,200 rpm and 520 lb-ft of torque at 5,250 rpm. In your opinion, would switching to either a Performer RPM or Indy 440-2D intake make better torque and horsepower numbers in the same 6,500-rpm range? What cfm carb would you recommend for this combo?Jared SchlampVia e-mail