Chrysler Slant-6 Engine - Significant Production Changes

Significant Production Changes

• The combustion chamber shape was slightly modified for 1967 to promote more complete combustion and reduce exhaust emission toxicity.
• All G engines used forged steel crankshafts until the middle of model year 1976, when a less costly cast-iron crankshaft was introduced. The cast crankshaft uses a different block, different main and connecting rod bearings and different connecting rods.
• The counterbore in the rear flange of the crankshaft was a 1 1⁄₄-inch diameter until 1967. For 1968, it was enlarged to 1 1⁄₂ inches. This difference has implications when swapping engines and automatic transmissions across this date line.
• All G-engines used solid valve lifters through the 1980 model year, with the exception of a small production test of hydraulic lifters in the 1978 model year. For model year 1981, all North American G-engines received top-fed hydraulic lifters. Retrofitment in both directions is possible.
• Emission control devices and systems, carburetor make and specification, and engine assembly details changed over the years to comply with market requirements and preferences.
• Electronic ignition, which had been made available on V8 engines late in 1971, was made standard equipment on all engines including the RG in 1973.
• Induction-hardened exhaust valve seats and upgraded exhaust valves were made standard in 1973 to withstand prolonged operation on no-lead fuel.