Pontiac Engine Bore Sizes




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Pontiac Inline Engine Bore Sizes

Cubic Inch Style Year Produced Bore Stroke

223.4

L-head Straight 8

1933-1935

3 3/16

3 1/2

208

L-head Straight 6

1935-1936

3 3/8

3 7/8

232.3

L-head Straight 8

1936

3.25

3.50

222.7

L-head Straight 6

1937-1940

3 7/16

4.00

248.9

L-head Straight 8

1937-1949

3.25

3.75

239.2

L-head Straight 6

1941-1954

3 9/16

4.00

268.4

L-head Straight 8

1950-1954

3 3/8

3.75

194.5

1/2 of 389

1961-1963

4.06

3.75

215

Overhead Valve 6

1964-1965

3.75

3.25

230

Overhead Cam 6

1966-1967

3.87

3.25

250

Overhead Cam 6

1968-1969

3.88

3.53







Pontiac V8 Engine Bore Sizes

Cubic Inches Year(s) Bore (inches) Stroke (inches) Main Journal size (inches) Rod Journal size (inches)
265 1977 ? 3.750    3.000    3.00    2.250
287 1955 3.750    3.250    2.50    2.20   
301 1977 ? 4.000    3.000    3.00    2.250
303 1969-70 4.1250 2.840    3.00    2.250
316/317 1956 3.9375 3.250 2.50    2.20   
326 1963 3.781  3.750    3.00    2.250
326 1964-67 3.71875 3.750    3.00    2.250
347 1957 3.9375 3.5625 2.623 2.20   
350 1968-77 3.8750 3.750    3.00    2.250
366 1969-70 4.1530 3.3750 3.00    2.250
370 1958 4.0625 3.5625 2.623 2.20   
389 1959-66 4.0625 3.750    3.00    2.250
400 1967-79 4.120    3.750    3.00    2.250
421 1961-66 4.09375 4.000    3.250 2.250
428 1967-69 4.120    4.000    3.250 2.250
455 1970-76 4.150    4.210    3.250 2.250