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| − | ==Introduction==
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| − | Over time a timing set will wear, retarding the cam timing in the process. This will hurt performance and economy.
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| − | ==Measuring timing set wear==
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| − | Estimating the amount of wear on the timing chain and gears is not hard to do with a reasonable degree of accuracy.
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| − | You can get an idea of how bad the timing chain is stretched by removing the plugs and, by hand, rotate the engine backwards (CCW as viewed from in front of the car) until you feel the slack has been taken out of the chain. Watching the rotor with the distributor cap removed can help- the instant the rotor moves, the slack is gone. Mark the damper at the TDC line of the timing tab (or any easy to see stationary point on the engine).
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| − | Then rotate the engine CW and stop as soon as you feel the added resistance (and see the rotor begin to move) when the slack in the timing chain has been taken up. Mark the damper a second time to your reference point. The distance between the two lines is how much slack there is. You can do this several times to get a feel for it.
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| − | The wear can be estimated by comparing the distance between the lines to the timing scale. If the timing scale shows that 10 degrees = about 0.7" (which is what it will be if the damper is 8" in diameter), use that to tell how many degrees of slop there is in the chain.
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| − | If the damper diameter is something other than 8", you may do this:
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| − | Measure the damper diameter, multiply diameter by 3.14 to get the circumference.
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| − | Divide the result into 360 to get the distance for 1 degree.
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| − | Divide the amount of slop by the distance equal to 1 degree and the result is the total amount of slop in the timing set.
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| − | ==Using a timing tape to estimate wear==
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| − | You can also easily make a [http://www.crankshaftcoalition.com/wiki/How_to_make_a_timing_tape temporary timing tape] that will make this easier to measure once the tape is on the damper. Simply mark or write down where the slack is removed, rotate the engine CW until the slack is again removed and the difference is the amount of slop in the timing set.
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| − | The timing tape is also useful for setting the total timing and for setting up a performance timing curve for the ignition, without needing a dial back timing light.
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| − | [[Category:Engine]]
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| − | [[Category:Adjust valves]]
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