Ram Air and 400
Short answer: A firsthand account from a member who raced a 1968 Ram Air convertible (with Pontiac engineering contacts) — on the 400’s special engineering and how the Ram Air engine behaved.
- “Safe at 160”: after the Corvair “unsafe at any speed” era, the 400 got chassis reinforcements not on the Camaro or 350 — triple-welded rear spring shackles and lengthened front control arms (rear attach point ~13″ behind the axle) for much more strength.
- Ram Air engine: built to hold together to ~8000 rpm with special anti-pump-up lifters, but redlined at 5100 only because oil pooled under the valve covers faster than it could drain (he blew a valve cover proving it).
- Fuel at sustained high rpm: the float valve opening is too small; substituting the 1/8″ seat and float from a Buick Roadmaster largely fixed it. He also added an electric pump at the tank as a booster. Fuel use was heavy — ~5 gallons over four 1/4-mile runs; ~8 mpg with the 4.11 axle, ~12 with the 3.08.
- Linkage: the Corvette logarithmic throttle linkage (only up to 1/2 throttle until the last 1/8″) made it far more drivable, especially in the rain.
- Top speed: with the 3.08 he saw 165 (redline 150) in a short safe blast, with plenty left — though turbulence made the ride rough; better aero was wanted.
- Cam: the Ram Air cam had more overlap and ~.100″ more lift, requiring doubled valve springs — which is why bolting just the Ram Air intake onto a standard 400 doesn’t transform it (though the RA intake alone adds ~15 hp from better volumetric efficiency).
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Content last modified: June 13, 2026 at 10:06 am
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