FCR Performance offers a complete line of custom-spec split-duration hydraulic flat-tappet camshafts for Olds applications and 0.050-inch-intake duration ranges from 217 to 233 degrees depending upon the application. Fritsch says that torque-converter stall speed, rear-axle gear ratio, if air conditioning will be used, and the car's intended overall usage dictates which grind he suggests for a particular build.
Retaining the original cast-iron four-barrel intake manifold or buying an aftermarket Edelbrock Performer are suitable choices if you wish to retain your T/A's original carburetor, and air cleaner and Shaker assembly. Fritsch suggests an Edelbrock Performer RPM and drop-base air cleaner assembly from Blocker's Performance (www.blockersperformance.com) to maximize performance, however. In addition, he prefers a Demon 650 carburetor and Holley HP125 electric fuel pump over the stock components, but says an older-vintage Oldsmobile Q-jet can also be used if it's jetted accordingly.
The 403's stock cast-iron exhaust manifolds are very restrictive. Fritsch says tubular headers are required for maximum performance, but adds that finding a set to fit the Firebird chassis can be somewhat difficult. In addition to headers, he suggests 3.00-inch-diameter head pipes with a cross-pipe exhaust system, high-flow cats and low-restriction mufflers of your choice, and 2.50-inch tailpipes.
Engine rpm shouldn't exceed 5,800 in this configuration, so an ignition system with rev limiting capability (like an MSD 6AL box) is required. If the original HEI is in relatively good condition, it can be reused but must be recurved to provide 35 degrees of total spark lead. If extra funds are available, Fritsch feels an MSD billet distributor is a better choice.
With said modifications, Fritsch says to expect a boost of as much as 190 additional horsepower over the stock rating, taking the total toward 375, while torque output should near 475 lb-ft. When combined with a gear ratio in the 3.23 to 3.73 range and a torque-converter stall speed of 2,400-2,800 rpm, the combination should provide strong performance while maintaining good street manners. That should be the ricers at bay! For more information, contact Terry Fritsch directly at (402) 596-1800 or through his website at www.fcrparts.com.