Firebird QuadraJet ‘Tab’ for 1967 / 1968
Short answer: There’s a long-standing claim that 1967–68 Firebird 400 carbs had a small bent tab/link limiting how far the secondaries open — supposedly to keep the Firebird below the GTO’s rated horsepower under GM’s “10 lbs per hp” rule. Many magazines and books mention it, but it’s not fully settled.
The evidence both ways:
- Sources citing the tab include Hot Rod (3/68), Special Interest Autos (10/86), Motor Trend (12/91, Jim Wangers), The Fabulous Firebird (Lamm, 1979), and the Firebird Decoding Guide (DeMauro, 1997) — describing a tab on the throttle linkage limiting the secondaries to roughly two-thirds to 90% open.
- Against: Firebird and GTO carbs often share the same part number (so the same base plate and throttle linkage), with the real difference being the jetting. Careful inspection of original carbs hasn’t reliably turned up the tab — though one member reports an unrestored Firebird carb that has the bent tab and a different link part number.
Bottom line: the rated-horsepower difference between Firebird and GTO 400s is documented, but the exact carb component remains debated — research continues.
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Content last modified: June 13, 2026 at 10:06 am
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