What was the standard engine displacement in the 1967 Pontiac GTO?

The standard engine displacement in the 1967 Pontiac GTO was 400 cubic inches.

Pontiac revised the GTO’s V8 for 1967 by enlarging the earlier 389-cubic-inch engine’s bore, producing a 400-cubic-inch displacement. The 400 was offered in several versions, including an economy two-barrel engine, the standard four-barrel engine, and higher-output variants. The standard version was rated at 335 horsepower.

That 400-cubic-inch V8 was part of the GTO’s identity during a pivotal period for American muscle cars. The model had begun as an option package on the Pontiac Tempest, but by 1967 it had become an established performance nameplate with distinctive styling, heavy-duty components, and serious V8 power.

The common confusion is with the 389, which powered earlier GTOs, or with the 455, which became associated with later Pontiac performance models. The 1967 GTO did offer different 400 versions, but the displacement of its standard engine was still 400 cubic inches.