Piston Position

 

by Larry Young and Tom Young

[Technical Page]  [Cam Designs] [Cam Testing]

Below is a table of piston position for any given crankshaft angle.  Specifications for many of the cams for the Model T or listed in Cam Testing.  Details of the new cams and stock Model T cam are listed in Cam Designs.  For example, a stock Model T cam should close the intake valve at 51 degrees ABC (129 degrees BTC).  The table gives a value for distance below the block deck of 3.1209 in or about 3 1/8 in.  The Laurel-Roof cam closes the intake valve at 55 degrees ABC (125 degrees BTC).  The table gives a value for distance below the block deck of 3.0291 or about 3 1/32 in.

Crankshaft

Position

(degrees)

Distance

Below TDC

(in)

Distance

Above BDC

(in)

Distance

Below Deck

(in)

0

0.0000

4.0000

-0.3125

1

0.0004

3.9996

-0.3121

2

0.0016

3.9984

-0.3109

3

0.0035

3.9965

-0.3090

4

0.0063

3.9937

-0.3062

5

0.0098

3.9902

-0.3027

6

0.0141

3.9859

-0.2984

7

0.0192

3.9808

-0.2933

8

0.0250

3.9750

-0.2875

9

0.0316

3.9684

-0.2809

10

0.0390

3.9610

-0.2735

11

0.0472

3.9528

-0.2653

12

0.0561

3.9439

-0.2564

13

0.0657

3.9343

-0.2468

14

0.0762

3.9238

-0.2363

15

0.0873

3.9127

-0.2252

16

0.0992

3.9008

-0.2133

17

0.1119

3.8881

-0.2006

18

0.1252

3.8748

-0.1873

19

0.1393

3.8607

-0.1732

20

0.1541

3.8459

-0.1584

21

0.1696

3.8304

-0.1429

22

0.1858

3.8142

-0.1267

23

0.2027

3.7973

-0.1098

24

0.2203

3.7797

-0.0922

25

0.2386

3.7614

-0.0739

26

0.2575

3.7425

-0.0550

27

0.2771

3.7229

-0.0354

28

0.2974

3.7026

-0.0151

29

0.3182

3.6818

0.0057

30

0.3397

3.6603

0.0272

31

0.3619

3.6381

0.0494

32

0.3846

3.6154

0.0721

33

0.4079

3.5921

0.0954

34

0.4318

3.5682

0.1193

35

0.4563

3.5437

0.1438

36

0.4814

3.5186

0.1689

37

0.5070

3.4930

0.1945

38

0.5331

3.4669

0.2206

39

0.5598

3.4402

0.2473

40

0.5870

3.4130

0.2745

41

0.6147

3.3853

0.3022

42

0.6428

3.3572

0.3303

43

0.6715

3.3285

0.3590

44

0.7006

3.2994

0.3881

45

0.7301

3.2699

0.4176

46

0.7601

3.2399

0.4476

47

0.7905

3.2095

0.4780

48

0.8213

3.1787

0.5088

49

0.8526

3.1474

0.5401

50

0.8841

3.1159

0.5716

51

0.9161

3.0839

0.6036

52

0.9484

3.0516

0.6359

53

0.9810

3.0190

0.6685

54

1.0140

2.9860

0.7015

55

1.0473

2.9527

0.7348

56

1.0808

2.9192

0.7683

57

1.1147

2.8853

0.8022

58

1.1488

2.8512

0.8363

59

1.1831

2.8169

0.8706

60

1.2177

2.7823

0.9052

61

1.2525

2.7475

0.9400

62

1.2875

2.7125

0.9750

63

1.3226

2.6774

1.0101

64

1.3580

2.6420

1.0455

65

1.3935

2.6065

1.0810

66

1.4292

2.5708

1.1167

67

1.4650

2.5350

1.1525

68

1.5009

2.4991

1.1884

69

1.5369

2.4631

1.2244

70

1.5730

2.4270

1.2605

71

1.6091

2.3909

1.2966

72

1.6454

2.3546

1.3329

73

1.6816

2.3184

1.3691

74

1.7179

2.2821

1.4054

75

1.7542

2.2458

1.4417

76

1.7905

2.2095

1.4780

77

1.8268

2.1732

1.5143

78

1.8631

2.1369

1.5506

79

1.8993

2.1007

1.5868

80

1.9355

2.0645

1.6230

81

1.9716

2.0284

1.6591

82

2.0077

1.9923

1.6952

83

2.0436

1.9564

1.7311

84

2.0795

1.9205

1.7670

85

2.1152

1.8848

1.8027

86

2.1508

1.8492

1.8383

87

2.1863

1.8137

1.8738

88

2.2216

1.7784

1.9091

89

2.2568

1.7432

1.9443

90

2.2918

1.7082

1.9793

91

2.3266

1.6734

2.0141

92

2.3612

1.6388

2.0487

93

2.3957

1.6043

2.0832

94

2.4299

1.5701

2.1174

95

2.4638

1.5362

2.1513

96

2.4976

1.5024

2.1851

97

2.5311

1.4689

2.2186

98

2.5644

1.4356

2.2519

99

2.5974

1.4026

2.2849

100

2.6301

1.3699

2.3176

101

2.6626

1.3374

2.3501

102

2.6947

1.3053

2.3822

103

2.7266

1.2734

2.4141

104

2.7582

1.2418

2.4457

105

2.7895

1.2105

2.4770

106

2.8205

1.1795

2.5080

107

2.8511

1.1489

2.5386

108

2.8814

1.1186

2.5689

109

2.9114

1.0886

2.5989

110

2.9411

1.0589

2.6286

111

2.9704

1.0296

2.6579

112

2.9993

1.0007

2.6868

113

3.0279

0.9721

2.7154

114

3.0561

0.9439

2.7436

115

3.0840

0.9160

2.7715

116

3.1115

0.8885

2.7990

117

3.1386

0.8614

2.8261

118

3.1653

0.8347

2.8528

119

3.1917

0.8083

2.8792

120

3.2177

0.7823

2.9052

121

3.2432

0.7568

2.9307

122

3.2684

0.7316

2.9559

123

3.2932

0.7068

2.9807

124

3.3176

0.6824

3.0051

125

3.3416

0.6584

3.0291

126

3.3651

0.6349

3.0526

127

3.3883

0.6117

3.0758

128

3.4110

0.5890

3.0985

129

3.4334

0.5666

3.1209

130

3.4553

0.5447

3.1428

131

3.4768

0.5232

3.1643

132

3.4979

0.5021

3.1854

133

3.5185

0.4815

3.2060

134

3.5388

0.4612

3.2263

135

3.5586

0.4414

3.2461

136

3.5779

0.4221

3.2654

137

3.5969

0.4031

3.2844

138

3.6154

0.3846

3.3029

139

3.6335

0.3665

3.3210

140

3.6512

0.3488

3.3387

141

3.6684

0.3316

3.3559

142

3.6852

0.3148

3.3727

143

3.7015

0.2985

3.3890

144

3.7175

0.2825

3.4050

145

3.7329

0.2671

3.4204

146

3.7480

0.2520

3.4355

147

3.7626

0.2374

3.4501

148

3.7768

0.2232

3.4643

149

3.7905

0.2095

3.4780

150

3.8038

0.1962

3.4913

151

3.8167

0.1833

3.5042

152

3.8292

0.1708

3.5167

153

3.8412

0.1588

3.5287

154

3.8527

0.1473

3.5402

155

3.8638

0.1362

3.5513

156

3.8745

0.1255

3.5620

157

3.8848

0.1152

3.5723

158

3.8946

0.1054

3.5821

159

3.9040

0.0960

3.5915

160

3.9129

0.0871

3.6004

161

3.9214

0.0786

3.6089

162

3.9294

0.0706

3.6169

163

3.9371

0.0629

3.6246

164

3.9443

0.0557

3.6318

165

3.9510

0.0490

3.6385

166

3.9573

0.0427

3.6448

167

3.9632

0.0368

3.6507

168

3.9687

0.0313

3.6562

169

3.9737

0.0263

3.6612

170

3.9782

0.0218

3.6657

171

3.9824

0.0176

3.6699

172

3.9861

0.0139

3.6736

173

3.9893

0.0107

3.6768

174

3.9922

0.0078

3.6797

175

3.9946

0.0054

3.6821

176

3.9965

0.0035

3.6840

177

3.9980

0.0020

3.6855

178

3.9991

0.0009

3.6866

179

3.9998

0.0002

3.6873

180

4.0000

0.0000

3.6875

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