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Registered
Join Date: Jul 2001
Location: mt. vernon Wa. USA
Posts: 8,703
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mystery cams?
I am working on a 77 2.7S engine and the cams have reportedly been reground, to SC specs. Of course they are marked as stock 2.7 CIS cams with no added markings to indicate any custom regrind work.
Just to be safe, prior to cam timing, I measured the lobes of the left side cam and using a rocker arm ratio of 1.45:1, I come up with lift at .443/.390 ???? More lift than 2.7 CIS cams (.405/.350) , but not quite SC lift (.450/.395) Anybody have a good guess/know what i might have here? Recommendations regarding timing?........or do i need to send these in to have them profiled. regards, al
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[B]Current projects: 69-911.5, Previous:73 911X (off to SanFrancisco/racing in Germany).77 911S (NY), 71E (France/Corsica), 66-912 ( France), 1970 914X (Wisconsin) 76 911S roller..off to Florida/Germany RGruppe #669 http://www.x-faktory.com/ |
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11-23-2013, 07:09 PM
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I would rather be driving
Join Date: Apr 2000
Location: Austin, TX
Posts: 9,108
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Al. What was the valve lash when you measured? Or did you mic the lobes in two directions to get lift?
Did you measure more than one pair of lobes? Where these cams new or run? If run, could they be worn?
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Jamie - I can explain it to you. But I can not understand it for you. 71 911T SWT - Sun and Fun Mobile 72 911T project car. "Minne" - A tangy version of tangerine #projectminne classicautowerks.com - EFI conversion parts and suspension setups. IG Classicautowerks |
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11-24-2013, 06:44 AM
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Registered
Join Date: Jan 2004
Location: CT
Posts: 11,538
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Al
You can check them yourself with a home made cam doctor: DIY Cam Doctor Or you can send them to me and I will check them.
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Tom Butler 1973 RSR Clone 1970 911E 914-6 GT Recreation in Process |
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11-24-2013, 06:52 AM
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Registered
Join Date: Jul 2001
Location: mt. vernon Wa. USA
Posts: 8,703
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doctor
Quote:
i ran across your cam-doc post, while researching my cam grind. Thanks very much for the offer. if i can't resolve the identity of these cams, i may take you up on it....or make myself a cam doctor. great idea. al
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[B]Current projects: 69-911.5, Previous:73 911X (off to SanFrancisco/racing in Germany).77 911S (NY), 71E (France/Corsica), 66-912 ( France), 1970 914X (Wisconsin) 76 911S roller..off to Florida/Germany RGruppe #669 http://www.x-faktory.com/ |
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11-24-2013, 07:25 AM
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Registered
Join Date: Jul 2001
Location: mt. vernon Wa. USA
Posts: 8,703
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Quote:
0 lash, mic'd in two directions to determine lift. Run, but not worn. regards, al
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[B]Current projects: 69-911.5, Previous:73 911X (off to SanFrancisco/racing in Germany).77 911S (NY), 71E (France/Corsica), 66-912 ( France), 1970 914X (Wisconsin) 76 911S roller..off to Florida/Germany RGruppe #669 http://www.x-faktory.com/ |
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11-24-2013, 07:41 AM
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Registered
Join Date: Jul 2001
Location: mt. vernon Wa. USA
Posts: 8,703
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These cams were reportedly "SC" grind on 77 CIS cams, but still marked as 77 CIS cams, so by process of elimination:
I timed the cams at: 1.) 2.7 CIS specs: .40-.54 overlap, results in interference 2.) SC ...... specs: .90-1.1 overlap, results in interference 3.) SC........specs: 1.4-1.7 overlap............winner hmmmm regards, Al
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[B]Current projects: 69-911.5, Previous:73 911X (off to SanFrancisco/racing in Germany).77 911S (NY), 71E (France/Corsica), 66-912 ( France), 1970 914X (Wisconsin) 76 911S roller..off to Florida/Germany RGruppe #669 http://www.x-faktory.com/ |
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11-24-2013, 09:15 AM
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