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Registered
Join Date: Jun 2004
Location: Rio Rancho, New Mexico
Posts: 1,325
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With the degree wheel on the crank, at 13 degrees before TDC at crossover, the intake valve should be 0.050" (fifty thousands or 1.25mm) open.
Remember it isn't when the valve just begins to move. The 13 degrees is measured when the intake is .050" (1.25mm) open. This is with ZERO initial valve gap. When your all done timing you'll need to reset the initial gap to .004"(0.1mm). So, when you have the crank set to 13 degrees, turn the cam until the dial indicator shows .050" movement, then lock it down with the pin in the cam sprocket. Then rotate at least two crankshaft rotations and recheck at 13 degrees. It should have opened the intake 50 thousandths (.050" or 1.25mm). This all gets a little confusing going back and forth with milli-meters and thousands of an inch. Throw in degrees and all the other numbers, no wonder is seems like one big mystery for first timers. American cam makers use .050" for their spec. Porsche uses 1.0mm (.03937") for their cams. Double check that the cam matches the card you have. If the card is correct, the intake valve should be .050" from full closed at 55 degrees after BDC, or 100% all the way closed at 64 degrees after BDC. This MUST match if the card matches the cam. If things don't match write down what the intake opening and closing degrees are and get back to us or Web Cam. Hang in there, the smoke will rise.
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DOUG '76 911S 2.7, webers, solex cams, JE pistons, '74 exhaust, 23 & 28 torsion bars, 930 calipers & rotors, Hoosiers on 8's & 9's. '85 911 Carrera, stock, just painted, Orient Red |
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12-30-2005, 08:40 PM
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Registered
Join Date: May 2003
Location: Galway, NY
Posts: 97
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Doug, Good call on the lash, when I timed it with the degree wheel I forgot to go zero lash and fifty thousandths. I just needed to get away from it and clear my head. It All makes sense now.
George, By rabbit ears I assume you mean the cam that has the lobes on the same side... I have that cam installed over cylinders 4 5 & 6 (right side). I'm 99% sure the cams are installed correctly. I got myself a new dial gauge and new knowledge from Wayne's book and from the members here. I'm gonna give it one more shot. I appreciate everyone's help, I've learned a lot and still have lots to learn. Thanks  Happy new year too! |
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12-31-2005, 03:10 PM
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