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gottarideduc gottarideduc is offline
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Join Date: Jul 2007
Location: US
Posts: 7
I'm a bit late to the thread, but perhaps not too late...
There is considerable play between the pin, the sprocket and the nothc in the drive flange. This fact accounts for the movement observed by some posters while tightening the cam nut or bolt. Keeping the mechanism loaded in one direction while changing the setting and tightening fasteners minimises this effect.
FWIW, my procedure for timing the cams:

Preliminaries: Initially set the cams slightly advanced (keyway slightly to left of vertical). Not too much or with hot cams/high compression/tall pistons you'll get interference. Have all rockers installed and all valves adjusted. It does make a difference. Torque both cam nuts/bolts every time. It also makes a difference. Install mechanical tensioners. If unavailable, use C-clamps to pull the idler to the chain case. Tension chains tight, but not dead tight. Install degree wheel and determine TDC with dead stop method. Pulley works, but could be off. Install and zero indicator, obviously Lubricate the threads and surfaces that slide (side of the nut, under head of bolt) with a moly lube. Porsche are even very specific which lube is approved, but I use what comes with the ATP rod bolts or CV joint grease.

Procedure: Turn crank to desired lift. Long handled wrench on pulley nut works well. Crank will be beyond TDC. Holding the crank with the wrench, loosen the nut/bolt and slowly turn crank back to unload the pin, move pin to next hole until it slides in. Reverse direction on crank and keep pressure on while torquing the nut/bolt. Turn back until the indicator is at 0, then forward to desired lift as before. Repeat until as close to spec as possible. Final check by turning forward a whole cycle. My goal is to get within at least .05 mm. Advanced cam is better than retarded. Finally, if in doubt, check piston to valve clearance by threading a wide nut on a valve cover stud and using a prybar repeatedly push the valve open to feel the play while slowly turning the crank past TDC. 0.020 in with stock valve springs. At .010 you can usually hear contact noise at around 6.5 G due to float.

Couple hints: There should be no axial play between the cam and the sprocket.
When using a nut, be careful that the huge wavy washer is centered. The hole in it is large enough to allow it to get caught on the lip of the sprocket. Result: The nut, while torqued, will come loose.

Has worked well for me. I'm sure there are other methods which work just as well. I'm not preaching gospel.
Old 10-01-2007, 07:17 PM
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