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TIMING CHARTS
These charts can be used to measure the timings of an engine much more easily and just as accurately as any other method. To measure the exhaust, transfer and boost port timings it is only necessary to take the cylinder head off the engine and push the piston to the bottom of the stroke (BDC). Use a vernier caliper (digital if possible) or it is possible to use an accurate small steel rule also. With digital vernier calipers, measure down from the top of the liner to the piston using the depth gauge, then reset to zero. Take the liner out, measure from the top of the liner to the top of the port and compare that measurement to the chart, this will give the port timing duration(total open period). To measure the induction timing, measure again to BDC and reset to zero, turn the crank until the port starts to open or close, take the measurement, compare to the chart to show the before and after TDC timing measurement ( TDC = top dead centre ) A LOT EASIER THAN USING A TIMING DEGREE WHEEL! If these charts are not comprehensive enough or do not cover the engines that you use then we sell the ETP range of engine tuning kits. ETP2 is for all nitro marine engines. This contains software which displays port timings, blowdown, trapped and geometric compression ratios and tuned pipe lengths. The text and pictures accompanying the software describe all aspects of modifying an engine and include step by step instructions. ETP5 is for Zenoah engines only and this program is unique in that it shows how to measure the port timings from the base of the cylinder. click here for ETP2 click here for click here for ETP2 click here for ETP5
Induction opening BTDC
120
3.29
121
3.34
122
3.40
123
3.45
124
3.51
125
3.57
126
3.62
127
3.68
128
3.74
129
3.79
130
3.85
131
3.91
132
3.97
133
4.03
134
4.09
135
4.15
136
4.21
175
6.80
176
6.87
177
6.95
178
7.02
179
7.16
180
7.24
181
7.31
182
183
7.38
184
7.46
185
7.53
186
7.60
187
7.68
188
7.75
189
7.83
190
7.90
191
7.98
192
8.05
193
8.13
194
8.20
195
8.28
196
8.35
197
8.43
150
0.83
151
0.77
152
0.72
153
0.67
154
0.62
155
0.57
156
0.53
157
0.49
158
0.44
159
0.40
160
0.37
52
12.76
53
12.62
54
12.49
55
12.35
56
12.21
57
12.07
58
11.93
59
11.78
60
11.64
61
11.50
62
11.35
63
11.20
64
11.06
65
10.91
66
10.76
67
10.61
68
10.46
69
10.31
70
10.16
71
10.01
72
9.86
73
9.71
74
9.56
75
9.41
Induction Timings before & after TDC
RETURN TO MAIN PAGE ©Dave Marles, Prestwich Model Centre, 1 Mill St., Golborne, Nr Warrington, England.