the Tempest. With an identical bore and stroke of and it was precisely half the displacement of the 389 and shared numerous parts with the V8, yet weighed considerably more than half as the engine lower half and block casting were not simply divided down the middle. 326/336 In 1963 Pontiac dropped the Buick division built 215 cu. in. aluminum V8 it had offered in the Tempest and replaced it with a small-bore version of the standard Pontiac V8. It shared the 389's stroke, but its bore was for a displacement of . It was rated at with 8.6:1 compression and at 10.25:1 compression. Both used a single two-barrel carburetor. In 1964 when the new "A" body intermediates came out there was a new corporate (GM) engine size limitation to anything less than . and so the 326 bore size was reduced to , giving a true . The 326 subsequently became the optional V8 engine for Tempests, and later the Pontiac Firebird, through 1967 and maintained the 17 degree cylinder head valve angle for its entire production run. A higher-output four-barrel carburetor version was offered, called the 326 HO (High Output). With higher compression and dual exhaust it produced for 1963–1964, and for 1965 through 1967, its final year. 400 For 1967, Pontiac retired the and replaced it with the 400 cu in (), a 389 bored-out by + to a bore and stroke of . The 400 remained in production through the 1978 model year, with 1979 cars receiving engines produced the previous year. In basic 2-barrel form it produced 290 horsepower and 428 ft. pounds of torque in 1968. This was the engine installed in the Pontiac Executive line of large cars and its largest station wagon, the Pontiac Safari. In 1967, the cylinder head design was improved for the 400 4-barrel engine. The valve angle was reduced from 17 degrees to 14 degrees for better breathing. 1967 was the last year for closed-chambered heads. The "670" head was a 1967-only casting, and the only PMD head to have a closed chamber with the new 14 degree valve angle. The 400 2-barrel kept the 17 degree valve angles for '67; starting in '68 all Pontiac V8s went to the 14 degree valve angle. Pontiac went to open-chambered heads in some 1967 models and all 68 and up to improve power, engine breathing and reduce emissions. The valve