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abides.
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Cam timing sanity check
After getting my cams timed nicely, checking my valve clearance, and installing my rockers, I got little ahead of myself and installed the tensioners and sealed up the chain boxes.
Now when I'm adjusting the valves, it seems like the right hand cam is off by one crank revolution, as though 1 and 4's valves are both closed at #1 TDC. Could I have somehow rotated the right hand cam 180 degrees? Am I missing something obvious? Can someone tell me which way the #1 and #4 cam lobe should point at TDC?
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Graham 1984 Carrera Targa |
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911 2.2 T targa
Join Date: Jun 2012
Location: Netherlands
Posts: 89
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The cranks turns twice (720 degrees) for the camshaft to turn once (360 degrees). So you have a TDC for cylinder 1 in ons turn and in the next turn it is for cylinder 4. When cam timing is done correct you have closed valves (rocker is able to move) at ingition TDC for one cylinder and rocker is tight at overlap TDC for the other cylinder. So both valves should not open at same TDC. You are probably of 180 degrees on one.
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Registered
Join Date: Oct 2008
Location: Nash County, NC.
Posts: 8,468
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When you're adjusting the rockers, you're on the back of the cam lobe (including visually). If you're right, one rocker either 1 or 4 has started to move as the opposite doesn't for nearly 300 degrees of crank turning.
Bruce |
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abides.
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Argh. I guess I'll just have to take a fresh look. Frustrating after being so careful to get the timing process correct.
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Graham 1984 Carrera Targa |
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abides.
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Sure enough, the cam was 180 off.
I was misunderstanding the instructions, and rather than just move the crank a few degrees to the next TDC after I reached the set point, I rotated it 360 + a few. Obligatory progress shot: ![]()
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Graham 1984 Carrera Targa |
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911 2.2 T targa
Join Date: Jun 2012
Location: Netherlands
Posts: 89
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Looks very nice!
Good that you corrected before damage was done |
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