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I'm reading Ludvigsen's "Excellence Was Expected". I'm familiar with camshaft timing, i.e. exhaust valve opens a certain degree before BDC, and it closes a certain degree after TDC, etc. Ludvigsen gives camshaft timing as, for instance 24/56/54/14 (for a 1973 911T). I can't figure out which of these numbers designates the opening, which designates the closing, which numbers are for exhaust and, which are for intake. It should be simple to figure out, but I just can't get it. I Googled for all sorts of things like camshaft timing designation, or notation, etc. but I could not find anyone else who uses this convention. Can someone explain? I've been reading this series off and on for more than a year, and it bugs me that I can't decipher this. Thanks.


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My first google search for "camshaft timing" gave me this result on the first page:


Based on that, looks like it is:

(intake: open degrees before TDC) / (intake: close degrees after BDC) / (exhaust: open degrees before BDC) / (exhaust: close degrees after TDC)

I'm no expert though, so hopefully someone will correct me if I'm wrong.

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This might help...


If that's not enough info...

If you are contributing member I think more info about cam timing is in one of the after sales training engine pdfs available for download here.

Just curious why you need to know the cam timing, are you looking to modify (i.e. have you installed aftermarket cams?)

Edited by logray
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