SMALL BLOCK FORD BULLET AND PRO BULLET COMPRESSION RATIO CHART Common Ford aftermarket cylinder head combustion chamber sizes Caution:This is only a guide. You should always confirm your actual combustion chamber volume. AFR 58cc /61 cc /68 cc Dart  58cc / 64 cc Edelbrock 60 cc / 70cc Ford Racing 58 cc 64 cc Trick flow Twisted Wedge, Track heat and R series 61cc / 65cc CNC ported Trick Flow High Ports  64 cc World Products 58 cc /64 cc Combustion chamber Volume (in CC's) 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 306 Flat Top -3cc 11.51 11.34 11.17 11.01 10.85 10.70 10.55 10.41 10.27 10.13 10.00 9.88 9.75 9.63 9.51 9.40 9.29 9.18 9.08 8.97 8.87 8.78 8.68 Dish -13cc 10.00 9.88 9.75 9.63 9.51 9.40 9.29 9.18 9.08 8.97 8.87 8.78 8.68 8.59 8.50 8.41 8.32 8.24 8.15 8.07 7.99 7.92 7.84 331 Flat Top -3cc 12.39 12.20 12.02 11.84 11.67 11.51 11.35 11.19 11.04 10.90 10.75 10.62 10.48 10.35 10.22 10.10 9.98 9.86 9.75 9.64 9.53 9.42 9.32 Dish -13cc 10.75 10.62 40.48 10.35 10.22 10.10 9.98 9.86 9.75 9.64 9.53 9.42 9.32 9.22 9.12 9.03 8.93 8.84 8.75 8.66 8.58 8.49 8.41 Dish -18cc 10.10 9.98 9.86 9.75 9.64 9.53 9.42 9.32 9.22 9.12 9.03 8.93 8.84 8.75 8.66 8.58 8.49 8.41 8.33 8.25 8.17 8.10 8.03 347 Flat Top -3cc 12.91 12.72 12.53 12.34 12.17 11.99 11.83 11.66 11.51 11.35 11.20 11.06 10.92 10.78 10.65 10.52 10.39 10.27 10.15 10.04 9.92 9.81 9.70 Dish -18cc 10.52 10.39 10.27 10.15 10.04 9.92 9.81 9.70 9.60 9.50 9.40 9.30 9.20 9.11 9.02 8.93 8.84 8.75 8.67 8.59 8.51 8.43 8.35