LG4 vs. L69

Starting with a standard issue Chevy 305 small block, here are some interesting notes:

• both use aluminum intake
  • early LG4 models had a cast iron intake however
• both use the same heads
  • casting: 601
  • 58cc chambers (60cc ?), 178cc runners (158cc ?)
• valve size in L69 heads were larger
  • L69 : 1.84/1.50
  • LG4 : 1.76/1.46
• L69 has 9.5:1 CR (flat tops) [these numbers changed]
• LG4 has 8.6:1 CR (dished pistons) [these numbers changed]
• L69 has a special cam, from the L-81 Corvette (hydraulic)
  • This is NOT a roller cam
• L69 uses a performance calibrated PROM
• L69 takes advantage of special exhaust/catalytic converter
• L69 takes advantage of a higher stall torque converter
  • L69 : approximately 1900 RPM stall
  • LG4 : approximately 1200-1500 RPM stall
• L69 uses a better fuel pump (from the Z/28)
• the changes in the L69 setup yielded *roughly* 30 more horse power
• the same changes actually yielded slightly less peak torque for the L69, but had the advantage of a flatter torque curve overall