670 Heads
Short answer: The 670 heads are a late closed-chamber design with shrouded valves — but they’re a prized junkyard find. Per Pete McCarthy’s “Pontiac Racer’s & High Performance Handbook,” the 670 is unique:
- The only late closed-chamber design.
- The best-flowing intake port of any production head, including the Ram Air IV.
- The only big-valve head with exhaust-port air-injection holes (some Eastern cars lacked them).
- First of the high-performance heads with screw-in studs and stamped-steel pushrod guide plates.
Opened up (chambers enlarged like the 1968-and-later 400/428 heads) with good valve springs, they make an excellent high-compression head — dropping compression to roughly 9.5–9.75:1. As a stock head at a good price they’re worth buying; modified, they’re outstanding.
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Content last modified: June 13, 2026 at 10:06 am
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