LC engineering has a lot of great info on their site.
LC ENGINEERING Engine Tech
1975 - 1980 20R Cylinder Head
Round Intake Port
Round Exhaust Port
80/81 C.C. Chamber
Intake Valve Diameter 43mm
Exhaust Valve Diameter 35mm
1981 - 1984 22R Cylinder Head
Square Intake Port
Round Exhaust Port
82/83 C.C. Chamber
Intake Valve Diameter 44.5mm
Exhaust Valve Diameter 36.5mm
1985 - 1995 22R-22RE Cylinder Head
Square Intake Port
Pear Shape Exhaust Port
57 C.C. Combustion Chamber
60 C.C. Chamber (Turbo) Intake Valve Diameter 44.5mm
Exhaust Valve Diameter 36.5mm
Engine Block Identification
1975 - 1980 20R Block
Deck Height 11.280"
Stock Bore 88.5mm - 3.484"
Maximum Over Bore 90.0mm - 3.544"
1981 - 1984 22R Block
Deck Height 11.280"
Stock Bore 92.0mm - 3.622"
Maximum Over Bore 93.0mm - 3.662"
Big Bore Forged Piston Kit 94.0mm - 3.701"
1985 - 1995 22R-22RE "Laser Block"
Deck Height 11.090"
Stock Bore 92.0mm - 3.622"
Maximum Over Bore 93.0mm - 3.6662"
Big Bore Forged Piston Kit 94.0mm - 3.701"
All Toyota 20R - 22R - 22RE engines use the same crankshaft and connecting rods. To accommodate the different deck heights, Toyota changed the compression height (piston pin location).