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Wer bremst verliert
Join Date: Jan 2005
Location: Toronto, Ontario
Posts: 4,767
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Compression on fresh rebuild?
I am having starting problems on my fresh rebuild. Cylinders 2-6 all read 160-170lbs.
Cylinder reads 145lbs. This was also my first valve job. THe cylinders were all checked and ok, these are new Goetz rings from our host. New valves and guides by Bob Whyms. Is it possible for unseated rings to leak this much, or perhaps one of my rocker settings is off on #1? thanks
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2007 911 Turbo - Not a toy 1985 911 Cab - Wife's toy 1982 911 3.2 Indiash Rot Track Supercharged track toy 1978 911 3.0 Lichtbau toy "Gretchen" 1971 911 Targa S backroad toy |
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10-02-2006, 12:57 AM
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Join Date: Feb 2004
Location: California
Posts: 926
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the intake rocker clearance can change the compression reading slightly.
I would squirt a little oil in the cylinder and if the compression comes up, the rings probably need more time to seat.
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John Dougherty Dougherty Racing Cams |
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10-02-2006, 10:14 AM
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Wer bremst verliert
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Thanks John. Ugh, I was trying to avoid any oil in the cylinders...having a hard time starting as it is. So if my intake valve on #1 is off, could that mean my cam timing is then off too?
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2007 911 Turbo - Not a toy 1985 911 Cab - Wife's toy 1982 911 3.2 Indiash Rot Track Supercharged track toy 1978 911 3.0 Lichtbau toy "Gretchen" 1971 911 Targa S backroad toy |
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10-03-2006, 02:18 AM
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Location: California
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No the cam timing is not off. Since the other 2 cylinders on the same bank come up normal.
If you tighten the lash setting beyond the normal range, the intake valve will close later on the compression stroke. This can reduce the compression test reading. I would redo the lash on cylinder one and take a compression test. Then I would try the oil trick.
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John Dougherty Dougherty Racing Cams |
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10-03-2006, 07:05 AM
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Wer bremst verliert
Join Date: Jan 2005
Location: Toronto, Ontario
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Just to close this out, I ran the car around the track for about 100Km's, adjusted valves and get 160-168 on all cylinders.
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2007 911 Turbo - Not a toy 1985 911 Cab - Wife's toy 1982 911 3.2 Indiash Rot Track Supercharged track toy 1978 911 3.0 Lichtbau toy "Gretchen" 1971 911 Targa S backroad toy |
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04-04-2007, 02:29 AM
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