Cessna 172G Skyhawk (1966-1967)

The 1966-1967 Cessna 172G is the last 172 powered by the Continental O-300 six-cylinder engine. Aside from a longer pointed spinner and minor cowling refinements, it is functionally identical to the 172F: electric flaps, circuit breakers, 2,300 lb gross, Omni-Vision cockpit. Roughly 1,500 examples were produced across the 1966 and 1967 model years (some 1966 production was 172F, with 172G phasing in mid-year and continuing through 1967).

The 172G's significance is historical: it represents the end of the smooth-running Continental six-cylinder era. Starting with the 172H in 1967 (a single model year transition variant -- often grouped with 172G for resale purposes), Cessna prepared for the engine change. The 172I in 1968 introduced the Lycoming O-320-E2D four-cylinder engine that powered every 172 through 1986 except for the R172K Hawk XP.

For buyers who specifically want the six-cylinder Continental experience -- smoother idle, distinctive sound, slightly easier hot starts than the Lycoming -- the 172G is the newest 172 that offers it.

Distinguishing Features (vs 172F and 172H/I)

The 172H Transition Year (1967)

Some sources distinguish the 1967 model year as the 172H rather than 172G. The 172H is a single-year transition variant that retained the Continental O-300-D engine but introduced:

• 60-amp alternator (replacing the prior generator) -- significant electrical capacity improvement for radios and avionics
• Pneumatic reed stall warning (replacing the electric horn) -- the system used on every subsequent 172
• Shorter-stroke nose gear oleo strut -- minor handling refinement

For resale purposes, the 172H is often listed and priced alongside the 172G. Some 1967 aircraft were produced as 172G and some as 172H depending on serial number; the airframes are visually indistinguishable. Both share the same Continental O-300-D engine and the same desirability tier.

Identical to 172E/F: 114 KTAS cruise, 645 FPM climb at 2,300 lb gross, 7.0 GPH. The 172G/H added approximately 5-15 lbs of empty weight compared to the 172F due to the alternator (on H) and accessory mount changes, reducing useful load slightly to ~1,025 lbs.

The very last 172 production with the O-300. Field overhaul cost: $25,000-$32,000. By the late 1960s, the Continental O-300 was on its way out of mainstream production. Today, parts availability is "good" thanks to the large installed base across 172 (1956-1967), Cessna 170B (1953-1956), and Cessna 175 (1958-1962), but new-production parts for some accessory components are scarce.

The Lycoming O-320 conversion STCs (AVCON, Penn Yan, others) are particularly relevant for late-Continental 172s at overhaul time. Owners often weigh:

• Field overhaul ($25,000-$32,000): Keeps the Continental experience, retains type-correct configuration
• Lycoming O-320 conversion ($28,000-$38,000 including new engine): Better parts support long-term, modern engine controls, slightly better fuel economy

The conversion is a one-way change (returning to Continental requires another major investment) but is increasingly popular as the Continental support ecosystem ages.

Pricing is essentially identical to 172F. The "last Continental" status doesn't currently command a meaningful collector premium, though buyers specifically seeking six-cylinder smoothness may pay marginally more than for a comparable 172E.

The 1967 172H (with alternator) is sometimes valued slightly higher than 1966 172G/F due to the electrical system upgrade, but the difference is typically within negotiation noise ($1,000-$3,000).

Universal Cessna 172 pre-buy concerns apply. 172G/H-specific:

1. Generator vs alternator: 172G retains a generator; 1967 172H has an alternator. Generators are less common in active GA service today; verify the system is functional and budgeting for upgrades may be advisable.
2. Continental O-300 long-term support: Some accessory parts (specific carburetors, magneto installations) are increasingly scarce. Inspect engine accessories with future supply in mind.
3. Bridge-era serial numbers: 1967 aircraft can be 172G or 172H depending on serial number; verify the airworthiness certificate matches the airframe configuration.
4. Auto fuel STC interest: The Continental O-300 is well-suited to mogas via Petersen Aviation STC. If the airplane qualifies, the STC ($1,500-$2,000) pays for itself in 1-2 years of regular flying.