This Firebird is currently the only racecar with Ram Air IV heads (code-614) in modern NHRA Stock Eliminator competition. Head porting is strictly prohibited. Using bare, virgin castings, Burton measured a baseline of 225/140-cfm flow at 0.450-inch lift at 25 inches of pressure. Previous NHRA National Stock Eliminator champion Don Little of Westley, California, performed the head prep and assembly, including milling them to a 62cc combustion chamber per NHRA rules, and blocking off the heat crossover with aluminum. The heads produce an 11.55:1 compression ratio with 0.036-inch-thick Cometic head gaskets.
NHRA recently modified its rulebook to allow legal-replacement blocks, due to the scarcity of original, virgin castings. This 413ci Pure Pontiac engine is comprised of a MR1 cast-iron block, a ’70 Ram Air IV intake, and code-614 R/A-IV heads with absolutely, and we mean absolutely, no porting. What’s the contraption inline with the inlet radiator coolant hose? It’s another of Burton’s tricks—a one-way flapper valve, which allows him to quickly circulate ice water through the block to improve his engine’s performance in heads-up competition.
NHRA rules require stock valve diameters, which for the ’701⁄2 Ram Air IV are 2.11/1.77. Burton reveals his secret to obtaining better head flow without porting is to back-cut the intake valves 10-degrees and install them on a stock 30-degree seat. It increased intake flow 15-cfm over baseline. (The valves are Ferrea stainless steel.)
Comp 3⁄8-inch, 8.900-inch-length pushrods activate Harland Sharp 1.65:1-ratio roller rockers, which compress Manley Drag Race Triple valvesprings measuring 270-lb/in on the seat and 470-lb/in open.
The valvetrain is actuated by a Bullet hydraulic flat-tappet cam (268/272-degrees duration at 0.050, 110- degree LSA), which Burton advanced 2 degrees. He uses Shubeck ceramic puck lifters on the cam. Lift is 0.538/0.538 per NHRA rules.
Burton swears by his low-pressure Melling M-54D-S oil pump because it requires less horsepower to operate than a high-pressure pump. Another secret: He states the stock windage tray is prone to breakage and holds the oil too close to the crank. To replace it, he fabricated and installed a custom crank scraper, constructed from common 1⁄16-inch steel.
He also added extra baffling to a stock-replacement Moroso oil pan. “Upon hard launches, it prevents the oil from standing up in the back of the oil pan and getting into the rotation of the crankshaft and slowing it down,” he says. “Combined, the tricks are worth a 0.1 second.”
Burton has a secret for oil, too. “I run the engine on a steady diet of 0/10 weight Royal Purple, and change it every 50 to 70 runs. The light oils make the engine accelerate faster and the car go faster, probably 0.05 to 0.10-second,” he says.
Fuel, Intake, Carburetor, and Air Cleaner
The Firebird is outfitted with a 3.5-gallon fuel cell, ½-inch-diameter aluminum delivery and return lines, an Aeromotive A-2000 electric fuel pump with fuel return regulator, and an Aeromotive regulator set to 6.5 psi. His preferred fuel is 110-octane VP C-11.
A stock ’701⁄2 Ram Air IV intake (code 9799084) provides the platform for a 750-cfm Quadrajet, which was modified by Danny Ashley at Q-Jet Performance. What are its secrets? It has no primary metering rods, 0.061 jets in the primaries, and the secondary rods vary from 0.052 to 0.078 depending upon the altitude of the track. The carb is topped with a K&N base plate and 3-inch air cleaner, and two 1⁄8-inch phenolic spacer plates raise it off the intake.
Per NHRA rules, Stock Eliminator classes may use electronic ignition systems. This Firebird features an MSD Digital 6 control box and Pro-Billet distributor, Blaster 2 coil, Moroso 8mm wires, and Autolite AR72 plugs. Scott sets timing at 36 to 38 degrees, and the advance is locked out.