CAM TIMING 2
Correct cam timing is essential. Take the timing figures, add them together, add 180 and divide by 2. Deduct the first timing figure for Inlet and the last figure for Exhaust.
Example : 270 Ford SOHC
| INLET 23/65 | EXHAUST 65/23 |
| Add 23 + 65 = 88 | Add 65 + 23 = 88 |
| Add 180 = 268 | Add 180 = 268 |
| Divide by 2 = 134 | Divide by 2 = 134 |
| Minus 23 = 111 | Minus 23 = 111 |
| INLET SHOULD BE FULLY OPEN 111° AFTER TDC | EXHAUST SHOULD BE FULLY OPEN 111° BEFORE TDC |
Fit protractor on crankshaft at TDC and dial gauge on valve spring and retaining cap. Turn engine until dial gauge shows full lift has occured. Check number of degrees turned. Continue to turn until gauge shows drop from full lift. The true lift position is central, i.e. if full lift starts at 105° and finishes at 115° then true position is 110°. With a single cam engine it is only necessary to check inlet valves.
CAUTION
A new timing belt is essential whenever a new camshaft is fitted. Timing belts
should be renewed at manufacturer's specified intervals. A timing belt failure
can destroy an engine in seconds!