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at TDC (beginning of power stroke) both valves are closed. Why wouldn't you be able to adjust them at that point ?
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Belgian1979 wrote: ↑Sun Sep 09, 2018 10:34 am?
at TDC (beginning of power stroke) both valves are closed. Why wouldn't you be able to adjust them at that point ?
Warp Speed wrote: ↑Sun Sep 02, 2018 2:40 pm We adjust our valves when the exhaust is almost fully open, and when the intake is almost fully shut.
The difference in lash between a tdc base circle type measurement, the way I mentioned, and even differing places on the base circle, is typically caused by how the spring pressure from other cylinders are effecting cam position in block. This is aggravated by higher rocker ratios.
When running, all bets are off! Hahaha
Because the lifter is not on the cams base circle.Belgian1979 wrote: ↑Sun Sep 09, 2018 10:34 am?
at TDC (beginning of power stroke) both valves are closed. Why wouldn't you be able to adjust them at that point ?
I can't believe my lifters survive cause I set them at TDC.
im setting some lash at TDC on a racey solid roller tonight ...with a digital indicator on the adjuster nut i can rotate the degree wheel to 75deg BTDC before any movement on indicator and way more after TDC on intake..for ex i can rotate wheel 85 deg atdc before any movement and even more btdc. all through that movement indicator shows zero..so why cant i set both int and ex lash? i also did it the long way and lash did not change at tdcF-BIRD'88 wrote: ↑Sun Sep 09, 2018 12:41 pmBecause the lifter is not on the cams base circle.Belgian1979 wrote: ↑Sun Sep 09, 2018 10:34 am?
at TDC (beginning of power stroke) both valves are closed. Why wouldn't you be able to adjust them at that point ?
The EO IC method ensures that the lifter is in fact on the cams base circle at that point and near 180 degrees away of as if at peak lift.
The tdc method CA may well work OK for very short duration stock cams but not racey cams at all.
And if you found .001" or .002" difference then what? Is it gonna make any difference ?fdicrasto wrote: ↑Sun Sep 09, 2018 10:39 pm So let me suggest this. You have set your lash at TDC with a feeler gauge at say .020" or whatever setting you have chosen. Nice snug setting on both int. and ex. Now go do your rotation and find a position where ex. is opening (EO) and check with the feeler and then rotate to intake closing(IC) and check the lash. Do you find any variation from your initial lash settings ? I say you will.
Code: Select all
I N T A K E
Rocker Arm Ratio = 1.500 Valve Lash = 0.03000 Valve Angle = 23.0
VALVE Lift Opens Closes Duration
Deg BTDC Deg ABDC Area
0.00000 39.41 | 107.91 | 327.31 | 38.97
0.00050 38.34 | 105.99 | 324.33 | 38.97
0.00100 37.32 | 104.24 | 321.56 | 38.97
0.00600 30.24 | 91.66 | 301.91 | 38.93
0.01000 26.63 | 85.42 | 292.05 | 38.89
0.02000 20.52 | 76.85 | 277.37 | 38.75
0.04000 12.37 | 66.90 | 259.27 | 38.45
0.05000 9.08 | 63.12 | 252.19 | 38.36
0.10000 -3.83 | 48.62 | 224.80 | 37.21
0.15000 -14.29 | 37.63 | 203.35 | 35.92
0.20000 -24.23 | 27.62 | 183.39 | 34.14
0.25000 -34.41 | 17.44 | 163.03 | 31.86
0.30000 -45.46 | 6.41 | 140.95 | 28.50
0.35000 -58.05 | -6.17 | 115.78 | 24.53
0.40000 -73.80 | -21.88 | 84.32 | 18.46
0.45000 -101.00 | -48.82 | 30.18 | 6.83
CAM
0.00050 142.91 | 248.02 | 570.93 | 30.34
0.00100 140.22 | 247.04 | 567.26 | 30.34
0.00600 112.81 | 181.17 | 473.98 | 30.21
0.01000 90.58 | 160.43 | 431.01 | 30.03
0.02000 39.41 | 107.91 | 327.31 | 29.26
0.04000 16.09 | 71.28 | 267.37 | 28.44
0.05000 10.68 | 64.95 | 255.63 | 28.11
0.10000 -8.13 | 43.99 | 215.86 | 26.66
0.15000 -23.24 | 28.62 | 185.38 | 24.60
0.20000 -38.69 | 13.17 | 154.47 | 22.10
0.25000 -56.69 | -4.80 | 118.51 | 18.02
0.30000 -81.89 | -30.01 | 68.10 | 10.79