Reference Details
- Common issue
- A later 421 or reproduction dual-quad setup can duplicate the appearance without proving a late-1961 installation.
- Confidence
- documented
- Correct value
- Period-compatible 421 hardware agrees with either the 373-hp single-AFB or 405-hp dual-AFB manual-transmission configuration
- Where to check
- Block, crankshaft, heads, valve train, induction, ignition, exhaust, dates, parts records, and period installation records