Cylinder

63-64

65-67

64

65-67

65

64-67

68-72

73-76

77-

69

70

69-72

73-76

77-

80-

cc's

221

260

289-2V

289-2V

289-4V

289-4V

HP289

HP289

302-2V

302-4V

302-2V

302-2V

Boss 302

Boss 302

351W-4V

351W-2V

351W-2V

351W-2V

255

45

8.7

9.9

10.2

10.6

10.1

11.5

12.3

12.3

11.4

11.3

9.2

11.2

13.2

11.4

10.2

10.4

10.1

54.5

7.6

8.7

9.0

9.3

9.0

10.0

10.5

10.5

10.0

9.9

8.3

9.8

11.5

10.1

9.2

9.4

8.9

49.2

8.2

9.3

9.6

10.0

9.6

10.8

11.6

11.6

10.7

10.6

8.8

10.5

12.4

10.8

9.7

9.9

9.5

53.5

7.7

8.8

9.1

9.4

9.1

10.2

10.7

10.7

10.1

10.0

8.4

9.9

11.7

10.2

9.3

9.5

10.0

63

6.9

7.9

8.2

8.7

8.2

9.0

9.4

9.4

9.0

8.9

7.6

8.8

10.4

9.2

8.5

8.7

8.1

58.2

7.3

8.3

8.6

8.9

8.6

9.5

10.0

10.0

9.5

9.4

8.0

9.3

11.0

9.7

8.9

9.1

8.5

60.4

7.1

8.1

8.4

8.7

8.4

9.2

9.8

9.8

9.3

9.2

7.8

9.1

10.7

9.5

8.7

8.9

8.3

*58

11.0

11.0

*63

10.5

10.5

69

6.4

7.4

7.7

7.9

7.7

8.4

8.8

8.8

8.4

8.3

7.2

8.4

9.7

8.7

8.0

8.2

7.6

55.4

7.5

8.6

8.9

9.2

8.9

8.8

10.3

10.3

9.9

9.8

8.2

10.3

11.3

10.0

9.1

10.0

8.8

*Interchanging Boss 302 cylinder heads is not practical. Requires the use of special pistons when used on other engines.

Compression ratios shown in bold face are for the originally installed cylinder heads.

Find the modified compression ratio by crossing the line containing the bold value for one engine with the column of the

desired engine. For example, the 68-72 302-2V shows 9.0 compression in bold on line 5. Following line 5 to the column

containing the 351W-4V shows a value of 10.4. This means that using the 68-72 302-2V heads on a 351W-4V would

produce a 10.4 compression ratio.