'Cc Quickies
Wrong Wing: At least he's a Jets fan.
If all this sounds like a ton of work and time, it's only because it is. It will also be very frustrating if you try to do it yourself. We ran across a book on tuning mechanical fuel-injection systems for drag racing written by Bob Szabo that might be of use. We'd also highly recommend becoming fast friends with any drag racers or circle-track racers in your area who have experience with the Hilborn system. They can steer you in the right direction and save you untold amounts of grief. But even they probably won't be able to help with the part-throttle stuff because they rarely deal with that area of the fuel curve. Who knows, you might even be able to make this work well enough that driving the car would be fun.
If you really want the look of a Hilborn unit on the street without the constant tuning headaches and the pig-rich part-throttle air/fuel ratios, might we suggest converting the unit over to electronic fuel injection. The guys at Blower Drive Service (BDS) have a lot of experience converting these manifolds over to EFI, and it's not as complex as you might think. With EFI, you have total control over very finite points of the fuel curve and can dial in the idle, part-throttle, and WOT areas to make this a very streetable manifold. Craig Railsback of BDS tells us these EFI-converted manifolds offer unbelievably crisp throttle response once they are tuned properly. The initial cost for a complete EFI system from ACCEL, FAST, or BigStuff3 would be higher, but ultimately, the system will be far more enjoyable. You might even consider that budget EFI system from MegaSquirt.
'Cc Quickies
Chrysler by the Letters
A-Body: '60-'76 Dart, Duster, Barracuda
B-Body: '62-'79 Belvedere, Charger, Road Runner
C- Body: '65-'78 Newport, Polara, Fury
D-Body: Imperial, but it depends on when and whom you ask
E-Body: '70-'74 Barracuda, Challenger
F-Body: '76-'80 Volar, Aspen
Your example of using a slightly larger tire going from a 215 to a 235 on the same size wheel also made those front tires wider by 20 mm (roughly 31/44 inch). This additional tread contact area to the road is what improved your braking efficiency, overcoming the slight difference in height between those two tires. You are correct that a taller wheel-and-tire combination will rotate slower. But because it is taller and (we'll assume) heavier, it now creates much more centripetal force. This adds to the load the brakes must overcome to stop the vehicle. Remember that the brakes are attempting to overcome the vehicle weight and speed as well as the combination of the weight and speed of the tires and wheels. I think you would agree that a heavier car and/or heavier tires and wheels are more difficult to stop than lighter versions. All those big SUVs running around with 24-inch-tall wheels and tires or those monster off-road pickups with 38-inch-tall mud tires have a tough time getting stopped in OE-equivalent braking distances because their tires and wheels are much taller and heavier. You can't argue with basic physics-not that we don't try!
As for your question about mechanical fuel-injection performance versus a carburetor, the answer lies in manifold design rather than in the way the fuel is introduced into the engine. A tunnel ram may come closest to duplicating the runner length of an individual ram manifold like the Hilborn. We'd estimate those power levels to be similar with a slight advantage going to the Hilborn setup if properly tuned. The advantage of a single carburetor is that it is immensely easier to tune, remains in tune longer, and offers relatively trouble-free street operation.
Too Hot
Gary V., Blaine, MN: I've got a 260hp stock replacement 350ci Chevy crate motor that I bought in 1999. The bottom end has been rebuilt, the crank was ground, I added new H-beam rods, 10:1 hypereutectic pistons, and the rotating assembly has been balanced. I installed a set of Vortec cylinder heads that have been ported with 0.600-inch-lift springs, guideplates, bigger valves, new guides, pushrods, and I am using Crane Energizer roller rockers. Here is my problem. The stock valve covers were too short, and the rockers just barely touch the valve covers, making a ticking noise. I then bought billet-aluminum center-bolt valve covers, and the bosses for the center bolts will not allow them to clear the valvetrain. Could you suggest a steel, tall, center-bolt valve cover?