WARNING ...backdating 993 cam gears

[84toy]

If this has been brought up before...my apologies.

OK, there is lots of talk about backdating the one piece cam gears with no locating pin to the earlier style 2 piece units that use the pin. Porsche switched to a one piece (keyless) hub and sprocket sometime after 95 and some even have the keyways still cut.

If you have later cams (09 on the end) you might be in trouble backdating. Those cams have a section on the end that is machined down very slightly compared to all the earlier cams. The problem is that the early sprocket fits on that area and it will not center properly. The machined area is not much, perhaps .010 smaller and when everything is tightened, the sprocket won't be centered perfectly causing a out of round situation. It would be easy to assemble an engine and not notice this. It might run fine but it will certainly cause chain and sprocket and tensioner wear.

I checked several cams and they were all this way.

Here are some pictures to show what I am talking about....

[Bill Verburg]

Yes, my '97 cams were the same way. Most people doing this are buying new cams anyway, so the back date is just part of the spec.

[ChrisBennet]

Thanks for the heads up.
-Chris