Pontiac Firebird 1968 – 400 Convertible with H/O and RA components

Not every 1968 Pontiac Firebird 400 was built the same way. The H.O. package added a revised cam and free-flow exhaust for 335 horsepower, while the mid-year Ram Air II update brought new round-port heads, forged pistons, and 340 horsepower to those who knew to order it. Only 16,960 of that year’s 107,000-plus Firebirds left the factory as convertibles. Here’s what actually separated these engines under the hood.

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Order the wrong box on a 1968 Firebird build sheet and you got a 400 that merely sounded fast. Check the right ones, and Pontiac quietly built you something with a mid-year engine update most buyers never even knew existed. The H.O. and Ram Air designations on this era of 400-cubic-inch Firebirds weren’t marketing fluff — they represented genuinely different internals, different cylinder heads, and in one case, a completely different camshaft that arrived on dealer lots partway through the model year without much fanfare. Only a fraction of the 107,000-plus Firebirds sold that year left the factory as convertibles, and fewer still carried the full Ram Air hardware this one apparently has. What actually changed under the hood between a standard 400 and a 400 H.O. — and why does it matter so much to collectors now?

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H.O. Wasn’t Just a Badge

The 400 H.O. added roughly $350 over the base 400 and got there with free-flow exhaust and, when paired with the four-speed manual, its own revised camshaft profile. It was rated at 335 horsepower and carried a higher redline than the standard 400, though it still sat a notch below the top Ram Air package. All 400-cubic-inch Firebirds ran a single four-barrel carburetor and could be had with a three- or four-speed manual or an optional three-speed automatic — though the four-speed was mandatory on any car ordered with Ram Air.

The Mid-Year Update Most Buyers Missed

Pontiac introduced the Ram Air II package in April 1968, roughly halfway through the model year, replacing the original 335-horsepower Ram Air engine with a 340-horsepower version built around new round-port cylinder heads for better breathing, a higher-lift cam, forged pistons, an Armasteel crankshaft, and dual high-rate valve springs. A properly equipped Ram Air II convertible with the four-speed could reportedly run 0-60 in about 5.1 seconds and cover the quarter mile in the mid-13s — genuinely quick numbers for a full-size convertible built before radial tires existed. With total Firebird production climbing 23 percent to just over 107,000 units that year, and only 16,960 of those built as convertibles, a documented H.O. or Ram Air drop-top is a rare combination even by muscle car standards.

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