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Cam shaft rotation (Stiff)
Not sure if the cams should be very difficult to turn by hand???
I'm just now getting my chains hooked up and notice the cams are not turning by hand (at least easily). I could add a little more force and make them turn, but wanted to get some opinions on how much force (lbs) should be expected to turn the cams from the flywheel. The pistons are turning fine (I'd say around 5 lbs force to get those to turn (with no chains hooked up)... I've just never rotated the cams yet with the chains hooked up so I'm a bit confused. Thanks in advance for your responses. Eric J. 
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'82 SC 3.0L Targa, Chiffon/Brown “It all began when I was looking around but couldn’t find the car of my dreams anywhere. So I decided to build it myself.” - Ferry Porsche |
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06-06-2010, 08:24 PM
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Rocker arms installed? If they are (and they should) the adjusters should be backed out all the way. Engine at tdc and cams at there tdc mark. there might be some restriction from the cams compressing the valves even with the rocker arm adjusters fully loose. Did you check the cam's for free rotation without the rockers in and the cam housing torqued down? they should rotate freely
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08 Cayenne Turbo Last edited by James Brown; 06-06-2010 at 09:11 PM.. |
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06-06-2010, 08:31 PM
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1) The cams turn freely with the rockers out.
2) The adjusters are backed out all the way. I believe the springs on the valves are very strong (new) and may be making it hard to turn by hand. Any idea what poundage it should take to rotate the fly wheel with the rockers in place?
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'82 SC 3.0L Targa, Chiffon/Brown “It all began when I was looking around but couldn’t find the car of my dreams anywhere. So I decided to build it myself.” - Ferry Porsche |
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06-07-2010, 04:56 AM
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If the cam turns freely with the rockers out you are good to go. Make sure you install the end cap, shims and drive sprocket so you are sure the cam is centered in the tower before you turn it. If those components are not installed and the cam isn't centered, it can bind. You won't be able to turn the cam by itself by hand if the rockers are installed; too much spring resistance.
Lindy |
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06-07-2010, 05:46 AM
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yup.
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08 Cayenne Turbo |
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06-07-2010, 10:13 AM
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Ha... Glad I didn't decide to lay into the flywheel with the chains hooked up.
I thought you would be able to rotate the cams (with rockers in) by hand.... Apparently I'm wrong. Thanks for your responses! Eric J.
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'82 SC 3.0L Targa, Chiffon/Brown “It all began when I was looking around but couldn’t find the car of my dreams anywhere. So I decided to build it myself.” - Ferry Porsche |
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06-07-2010, 02:46 PM
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Fact is that turning the crank with the chains installed would not create a problem in itself; they would turn fine IF TIMED CORRECTLY. The procedure is to install the cams, then the chains and sprockets then one (intake #1) rocker to time the cam. If the cam is not timed properly you run the risk of running a valve into the top of the piston when the crank is rotated. Once the left cam is timed then you move on to the right side and repeat. But NO ROCKERS (except #1 and then #4) until the CAMS ARE TIMED.
Lindy |
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06-08-2010, 05:29 AM
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Grenade
Grenade
