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Join Date: Apr 2003
Location: Boston, MA
Posts: 132
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964 Cam Shaft Problem - How Bad?
While working on a valve adjustment, I found the following "ridge" on the # 5 exhaust cam at the top of the lobe.
 The car is a 90 C2 with 112k miles. Synthetic oil, autoxed, and a couple DE's, but mostly daily driving. Can you give me a glimpse of the future. Can it be reground? (I assume it's going to heck quick if I ignore it.....  ) What can cause this? There isn't any scoring on the cam, but it's a heck of a ridge.Thanks for any advice. The car hasn't got any leaks by the heads, so i'm trying to keep from taking the engine apart too far........ -Eric 90 C2 NER/PCA |
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02-05-2006, 06:12 AM
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Could it be that time for the top end ? How are the valve guides? Do you get smoke on decel.
In any case it's hard to see much and judge by your image but in general if there is a visible defect in the hardened surface of the lobe you need to get the cam shaft reground and the the rockers micropolished. Maybe a good time to upgrade to the Super C2 cam profile. That's what I am running in my 3.6 together with the NBD chip. It makes some nice improvements. If you do not attend this it will get worse quickly to the point where the cam goes completely flat. Cheers, Ingo
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1974 Targa 3.6, 2001 C4 (sold), 2019 GT3RS, 2000 ML430 I repair/rebuild Bosch CDI Boxes and Porsche Motronic DMEs Porsche "Hammer" or Porsche PST2, PIWIS III - I can help!! How about a NoBadDays DualChip for 964 or '95 993 |
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02-05-2006, 10:35 AM
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Yeah, it is feeling like a top end job.... but what causes this wear? Idiot doing the valve adjustments (me)? Flow problems?
Thanks, -Eric 90 C2 NER/PCA |
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02-05-2006, 12:53 PM
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looks like some serious wear on that lobe. if this is an indication of the stae of the engine then i would say rebuild, at least the top end. but while you are there.......
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Andy 1980 SC soon to be big hp 3.3t powered 73RSR Replica (well, I'm keeping the engine but everything else is going  )
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02-05-2006, 12:55 PM
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Join Date: Feb 2004
Location: California
Posts: 926
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That looks like more than the normal amount of wear. You probably have a plugged up oil squirter.
I would have to see it in person to tell if it can be reground.
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John Dougherty Dougherty Racing Cams |
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02-05-2006, 01:10 PM
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Location: Boston, MA
Posts: 132
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The rest of the cam lobes look fine (#3 exhaust has a little pitting on the end of the lobe, but I can't feel it with my fingernail)
John, i'll get the cam out this week, and give you a call about sending it out. Thanks, -Eric |
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02-05-2006, 07:27 PM
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1974 Porsche 911 Targa 3.6
