Ironically, one of the most pedestrian of all production automatic transmissions is most often the trans of choice with high-powered cars like Tom's. His good friend and fellow drag racer Ron Flood at Cedar Machine, who did all the machine work on the engine, also assembled the Powerglide. "It's got all the good parts in it, too," Tom says, which only makes sense with near double-century-mark power numbers. This includes a Dedenbear case and a Hughes 9-inch converter that leads to a Ford 9-inch with a mild 4.11 gear set. With this much power, you don't need a lot of gear. The Greek's Pro Shop welded the all-chromoly round-tube chassis complete with a 14-point 'cage to give the drivetrain something to hang on and to help somehow manage all that horsepower. Morrison supplied most of the components for the suspension with help from a set of Afco aluminum coilover shocks.
All the madness happening under the hood tends to distract your eye from the subtle changes going on with the body. Even card-carrying Chevelle guys might overlook the mild roof slice, artfully executed by Central Avenue Auto Body. Once you look, you may also notice the missing roof driprail, the shaved emblems, and the flush door handles. What isn't hard to miss is the multicolored paint explosion that slides down the Chevelle's flanks.
All told, it took Tom and his cohorts 51/2 years to complete this amazing Chevelle. But this isn't the end of the story. He has several dragstrip adventures in the works for the coming year, and there's already a chassis dyno tuning session planned as well as many more street miles. Regardless of where this car goes, it's bound to attract a following. The lunatic fringe always do.
Who: Tom Johnson
What: '67 Chevrolet Chevelle
Where: Moundsview, Minnesota
Short-block: Let's start with the Arias all-aluminum block stuffed with 4.600-inch-bore CP forged 15:1 pistons, Total Seal Hellfire rings for the nitrous, a Howards forged-steel 4.500-inch crankshaft, GRP aluminum rods, and Federal-Mogul bearings displacing 632 ci. Tom also added ARP studs, copper head gaskets, and a complete five-stage Moroso dry-sump system with the tank located just ahead of the radiator. For oil, Tom uses Redline 5W-30.
Heads and valvetrain: If you're really serious about making horsepower, a set of Dart Big Chief 14-degree heads is a good place to start. Tom then had Carl Foltz's Detroit-area CFE Racing work its port magic, which pulled the intake flow up to around 530 cfm using 2.50/1.88 titanium valves, Isky valvesprings, and titanium retainers followed by a Jesel shaft rocker system using 1.9:1 intake and 1.8:1 exhaust rocker ratios. The Comp Cams mechanical roller is a larger 60mm core that spins on roller cam bearings. Cam timing is, like everything else in this engine, big at around 260-plus degrees at 0.050 with 0.930-inch lift.
Induction: This is the attention-getting part of the car. CFE also built the sheetmetal intake that locates four split King Demon carburetors relocated to sit directly over a pair of intake ports. Each two-barrel flows 600 cfm, making the total potential airflow something ridiculous like 2,400 cfm. Tom also added two stages of Wilson Nitrous Pro Flow nozzles in the intake to add 400 hp in the first stage and up to an additional 300 on the second stage. All this is fed by a MagnaFuel electric pump flowing VP C23 race gas through matching purple anodized MagnaFuel regulators. Tom also has two NOS controllers, one for each stage, as well as EGT probes in each cylinder.
Exhaust: Tom built his own stepped headers, starting with a set of 23/8-inch primary pipes that bump up to 21/2 inches that then lead to a pair of DynaTech merge 4-inch collectors. Because the car sits so low, Tom built his own exhaust using SpinTech mufflers and 23/4x5-inch-wide oval tubing. The exhausts exit through the rocker panels just ahead of the rear tires.