Starting with the basics, fuel and ignition, we modified our Road Runner's fuel system with new 3/8-inch aluminum fuel line, and a Holley fuel pump and regulator. Sticking with our budget theme, we made the fuel line ourselves with a roll of tubing we got from a local race shop, and used a fuel pump and regulator we had in our spare race parts selection. To provide the extra ignition energy needed to power a high-performance big-block and to provide rev-limiting protection, we chose MSD's Digital 6 Plus ignition box. This ignition, along with an MSD Pro-Billet distributor, coil, and ignition wires, not only supplies the required additional spark energy, it also allows us to easily set two different levels of engine rev-limiting and gives us the option of retarding the ignition timing in case we ever chose to add nitrous oxide to our engine (not that it needs it).
To keep our high-performance engine cool, we knew it would be necessary to upgrade our radiator and cooling system as well. First, we replaced our car's original radiator with an aluminum replacement from Wizard Cooling. Wizard offers bolt-in replacement radiators for most Mopar body and engine combinations, and their radiators are a down-flow design just like the originals. Additionally, Wizard offers radiator and fan combinations, and we chose their kit that included two electric fans and custom fabricated aluminum fan shroud. To pump the coolant, a Mopar aluminum water pump housing was utilized along with a Milodon aluminum high-volume water pump and 160-degree thermostat.
With the engine taken care of, we moved on to the car itself, knowing that our factory style clutch and stock axles simply wouldn't be up to the task of handling our engine's additional torque. A clutch disc failure is no laughing matter, and a broken axle can at best leave you stranded, or at worst wreck your Mopar. With a quick call to Centerforce, we had a new DFX clutch, pressure plate, and SFI approved flywheel on the way, along with an input shaft bearing in lieu of a stock style bushing. Randy's Ring and Pinion provided our forged Yukon axles, and we cut them to length ourselves before installing new sealed axle bearings. We also considered sub-frame connectors necessary for a car with this kind of power, so we ordered a pair of bolt-in connectors from Competition Engineering.
While we could have gone over the top with this build in terms of the equipment needed to make this combination work, we decided instead to stick with the basics and only install the minimum equipment to ensure our engine would run properly and wouldn't destroy other parts of our Road Runner. We plan to mostly drive this car on the street but plan to take it to the strip as well to see how it performs. Our hope is that it will be quick enough we'll need to install other equipment like a driveshaft loop, safety harnesses, and possibly even a rollbar to make it legal at NHRA tracks. If we achieve our goal, we'll cover the additional safety installations in future issues. Be sure to go to our website, www.moparmusclemagazine.com, where we'll post video of our dragstrip testing.
7a The 833 four-speed is...
7a The 833 four-speed is a tough unit, but while ours was out we chose to inspect and reseal it with new gaskets and seals from Passon Performance...
7b ’ll reinstall our four-speed...
7b’ll reinstall our four-speed with a new clutch, pressure plate, and flywheel from Centerforce.
8 Centerforce clutch assemblies...
8 Centerforce clutch assemblies are known for their ability to hold a large amount of torque while having a reasonable pedal effort. We chose their DFX clutch and pressure plate, along with an SFI approved flywheel and a new throw-out bearing.
9 Instead of a pilot bushing...
9 Instead of a pilot bushing for the transmission input shaft, we chose a pilot bearing for a more precise fit. This bearing (ours is from National) is also useful for crankshafts that aren’t machined for a pilot bushing as the bearing fits in the larger diameter machined provision in the crankshaft—where the torque converter hub would ride in an automatic equipped car.
10 With our transmission...
10 With our transmission serviced by the crew at Inline Performance Specialists and our new clutch installed, in it went. Though arguably not as tough as an 18-spline 833, our 23-spline unit should be durable enough to handle our new big-block so long as we drive it reasonably and don’t push the limits by installing slicks.
11 We had already upgraded...
11 We had already upgraded our 8 ¾ differential with a new Sure Grip centersection from Randy’s Ring and Pinion but knew the stock axles wouldn’t withstand the torque of our new engine. Fortunately, Randy’s Ring and Pinion also offers forged Yukon axles for our application. We ordered their cut-to-fit axles and pressed on sealed “green” bearings before installing them in our car.
12 Mopar B-Bodies are structurally...
12 Mopar B-Bodies are structurally pretty sound, but by construction they aren’t as rigid as a car with a full frame. We ordered a set of bolt-in subframe connectors from Competition Engineering to give our Road Runner some extra strength. While we didn’t have time to install them by the time of this writing, we will definitely have them in place before we do any track testing.
13 We’re a lot closer to...
13 We’re a lot closer to driving and testing our car at the dragstrip with its new engine, but we’re not quite there yet. In a future issue of Mopar Muscle we’ll finish up the loose ends and then install a full exhaust system from tti and choose some wheels and tires for our Road Runner. Be sure to check out www.moparmusclemagazine.com as well for more photos of our progress.