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Finding true TDC

How to Degree a Cam

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Hi everyone, I have a question, I saw all 3 ways of finding true TDC, but why do all 3 ways show different values of TDC (12 degrees, 18.5, and 14.5)?

And in step 1 will always be 50 thou. of an inch? Independent of the engine?

I think you may be confusing cam timing with TDC - TDC is the CRANKSHAFT position, Top Dead Center, and is 0 degrees on #1 piston.

The various degrees you cite are probably for timing the camshaft in relation to the crankshaft. This is supported by the 50 thou' you mentioned being a common checking height (lift) for American sourced camshafts - this is not always the same lift, as different manufacturers may use a different lift, for example, 1mm is apparently common in Europe, and others may have 10 thou', 30 thou', or whatever. The camshaft specifications should have the lift the checking is to be done at, with the degrees.

If you could give a link to the actual video guide that's confusing you, I/we can clarify it further for you.

[edit] Ah, thank you David.

The video is the "Finding True TDC" in the "How to Degree a Cam" course.

I think the confusion is that between each method demonstration they reset the pointer to the indicted zero with the factory pulley timing mark. Notice that in the first two cases, they have to move the pointer about the same amount (about 3.5 degrees to the right). They mention this reset before the third method.

Bottom line -- start with the pointer close, and you can adjust it to be perfect using any of the methods.

I understood, thank u guys