How to find cam timing with motor assembled
(Created page with 'Occasionally, we encounter a motor which we did not build, but want to know the cam timing without having to remove the cam to read the manufacturer's stamping on the rear face o…') |
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The lobe separation angle (LSA) is figured by adding the intake centerline and the exhaust centerline and dividing by 2. So, in this case, we have the exhaust centerline at 111 and the intake centerline at 107. Added together equals 218. Divided by 2 equals 109 LSA. So, the complete timing figures for this cam would look like this.... | The lobe separation angle (LSA) is figured by adding the intake centerline and the exhaust centerline and dividing by 2. So, in this case, we have the exhaust centerline at 111 and the intake centerline at 107. Added together equals 218. Divided by 2 equals 109 LSA. So, the complete timing figures for this cam would look like this.... | ||
| − | Intake opens -1 degrees BTDC @ 0.050" tappet lift | + | *Intake opens -1 degrees BTDC @ 0.050" tappet lift |
| − | Intake closes 33 degrees ABDC @ 0.050" tappet lift | + | *Intake closes 33 degrees ABDC @ 0.050" tappet lift |
| − | Intake duration 212 degrees (-1 + 33 + 180) | + | *Intake duration 212 degrees (-1 + 33 + 180) |
| − | Exhaust opens 40 degrees BBDC @ 0.050" tappet lift | + | *Exhaust opens 40 degrees BBDC @ 0.050" tappet lift |
| − | Exhaust closes -2 degrees ATDC @ 0.050" tappet lift | + | *Exhaust closes -2 degrees ATDC @ 0.050" tappet lift |
| − | Exhaust duration 218 degrees (-2 + 40 + 180) | + | *Exhaust duration 218 degrees (-2 + 40 + 180) |
| − | Intake centerline 107 degrees ATDC | + | *Intake centerline 107 degrees ATDC |
| − | Exhaust centerline 111 degrees BTDC | + | *Exhaust centerline 111 degrees BTDC |
| − | Lobe separation angle 109 degrees | + | *Lobe separation angle 109 degrees |
Of course, finding valve lift is just as simple as rotating the crank through 2 complete revolutions and reading the dial. | Of course, finding valve lift is just as simple as rotating the crank through 2 complete revolutions and reading the dial. | ||
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