James & Son
Veteran Member
Here's my story.
I have spent a lot of time preparing to grind a taper relief to prevent loading of the follower as shown in pic.
The pickup on the base circle is exactly opposite to the injection lobe ramp and is located in the base circle just prior to the exhaust opening ramp.
Recently I helped a club member replace his 2006 jetta worn out stock cam. All 4 intake lobes were fairly good with one exceptional with virtually no wear(follower shiny smooth and flat). The base circles indicated flat on the minimally worn intakes. Therfore at least some( or most) of the original stock cams was flat during PD production.
I know the colt cam has a slight lobe taper with the injection lobe side of both exhaust and intake valve lobe being approx .00075 inch lower than the bearing journal side of each valve lobe. This taper is completely around the circumference, on the nose as well as the base circle.
The shocker
I assumed all after market cams would be flat just as the OE cam.
I bought a cheap Febi Belstein because they state in there iron clad contracts to suppliers( see web site) that they must build and supply to OE specs. Much to my surprise( I almost hit the floor) it has the exact same taper on the valve lobes as the colt cam( .00075 inch across width).
My question is when did this OEM cam design change, in that, a lobe taper was added. Was there a part number change and what was it.
There is about 3 or 4 different after market cams. I wonder how many bother to go to the extra expense of putting the taper on. This is a fairly complex and is only practical on a CNC grinder for small runs.
So the question is when and who came up with update. It seems as if VW did.
Edit: I realized the above picture of follower pickup on the cam would not be solved by me. VW had already put the taper on. Here is the answer to my question from Frank6.
http://forums.tdiclub.com/showthread.php?t=468200&page=3
I have spent a lot of time preparing to grind a taper relief to prevent loading of the follower as shown in pic.
The pickup on the base circle is exactly opposite to the injection lobe ramp and is located in the base circle just prior to the exhaust opening ramp.
Recently I helped a club member replace his 2006 jetta worn out stock cam. All 4 intake lobes were fairly good with one exceptional with virtually no wear(follower shiny smooth and flat). The base circles indicated flat on the minimally worn intakes. Therfore at least some( or most) of the original stock cams was flat during PD production.
I know the colt cam has a slight lobe taper with the injection lobe side of both exhaust and intake valve lobe being approx .00075 inch lower than the bearing journal side of each valve lobe. This taper is completely around the circumference, on the nose as well as the base circle.
The shocker
I assumed all after market cams would be flat just as the OE cam.
I bought a cheap Febi Belstein because they state in there iron clad contracts to suppliers( see web site) that they must build and supply to OE specs. Much to my surprise( I almost hit the floor) it has the exact same taper on the valve lobes as the colt cam( .00075 inch across width).
My question is when did this OEM cam design change, in that, a lobe taper was added. Was there a part number change and what was it.
There is about 3 or 4 different after market cams. I wonder how many bother to go to the extra expense of putting the taper on. This is a fairly complex and is only practical on a CNC grinder for small runs.
So the question is when and who came up with update. It seems as if VW did.
Edit: I realized the above picture of follower pickup on the cam would not be solved by me. VW had already put the taper on. Here is the answer to my question from Frank6.
http://forums.tdiclub.com/showthread.php?t=468200&page=3
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