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Registered
Join Date: Feb 2005
Location: LA
Posts: 1,183
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2.4 Heads - Flycut Spec
Ive been looking in the rebuild book and cant seem to find the spec for an OE 2.4 head. I am going to get them flycut tomorrow, i hope, and need to know the Factory spec and Tolerance that can be taken off..
Anyone know what I need to tell the machinist? And where/how to measure it? Thanks!!
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71 Targa 2.4 WEBERS 915 box Drivetrain - http://forums.pelicanparts.com/porsche-911-technical-forum/410787-drivetrain-project-complete-3yrs-pics.html Interior - http://forums.pelicanparts.com/porsche-911-technical-forum/452686-interior-refurb-carbon-fiber-71-a.html#post4433500 |
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09-18-2007, 06:39 PM
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Join Date: Jun 2004
Location: La Habra Hts, CA
Posts: 837
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Hmm, if it were me I would take/send the parts to a machine shop with a reputation for doing Porsche parts. There are enough things that can go wrong with the dimensional build ups plus the fact that these engines go together much different than anything your average machine shop is used to seeing. I know it's additional time and maybe money (shipping at least) but given the amount of labor that goes into putting one of these engines together, I found that taking chances just isn't worth it.
I don't have access to my book but I'll try to look it up tomorrow if someone else doesn't chime in first. Good Luck! |
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09-18-2007, 07:49 PM
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Join Date: Feb 2006
Location: Oahu
Posts: 2,303
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Will you need to give consideration to the chain-case as well?
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Jon |
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09-18-2007, 08:12 PM
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Location: LA
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John, not sure about the chain case, but when I rebuild I will check ...
Anyone know about the Factory spec on the heads ? ?
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71 Targa 2.4 WEBERS 915 box Drivetrain - http://forums.pelicanparts.com/showthread.php?t=410787 Interior - http://forums.pelicanparts.com/showthread.php?p=4433500#post4433500 |
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09-19-2007, 05:55 AM
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Registered
Join Date: Oct 2003
Location: Central Fla
Posts: 1,864
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cyl heads
Mitch, Dave Jarvis is in La. (Geismer ?) his ph. #225 473 8440 he can do that for you, long time 911 machinist, If for some reason he can't get to it we can do it here in central Fl. at JB Racing.
Mike Bruns JBRacing.com
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The two most useless things to a driver are the braking distance behind you and nine-tenths of a second ago. |
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09-19-2007, 09:22 AM
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GAFB
Join Date: Dec 1999
Location: Raleigh, NC, USA
Posts: 7,842
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I had my 2.4 heads fly-cut 1 mm. Using 0.5 mm base gasket instead of standard 0.25 mm, I shimmed out to a net 0.75 mm reduction in height. Note that this required shaving the chain cases as well, where they mate with the crankcase. Deleting the chain case/crankcase gasket was not sufficient. Dry test-assembly would lead you to believe there's no problem if you're not paying close attention - but the offset between the cam housing and chain housing is large enough to cause cam seal failure.
If I had it to do over again, I think I would offset-bore my wrist-pin bushings instead. No way would I give this job to someone who did not have air-cooled VW/Porsche experience. You're risking cam failure from improper fly-cut procedures.
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Several BMWs |
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09-21-2007, 06:57 AM
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