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Registered
Join Date: Apr 2009
Location: Grasonville, Maryland
Posts: 131
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Head studs on 2.7
I have two 2.7 cases. Both are in good shape. Neither had a pulled head stud and neither are case saved or time sert. Why use case saver/time sert? All the stuff I see has the head stud breaking, not pulling out the way out. If you are not racing engine and the engine is kept stock, i.e. not higher compression/aggressive cams, then why not replace with steel studs and move on?
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09-12-2009, 10:22 AM
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Join Date: Oct 2008
Location: Nash County, NC.
Posts: 8,512
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You still have to case save because the case has been weakened by the heat.
If you build without case work and ALL the studs are holding, it will be just minimal time before you have them pulling. The Dilival expands at approximately the same rate as the aluminum cylinders and thats the reason to install dilivar on a rebuild. The 2.7 is a completely different beast from the 3.0 so are the resolutions for repair. Bruce |
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09-12-2009, 11:34 AM
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Join Date: May 2008
Posts: 726
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The broken head studs your reading about are the old style dilivars used in the aluminum cased 3.0's and 3.2's. The only 2.7's with dilivars on the bottom row are the late 77's models. You will be taking a big chance by not doing this repair.
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09-12-2009, 12:43 PM
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Join Date: May 2003
Posts: 3,346
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The problems with studs pulling on 2.7 engines were common on street engines not race engines. The race engines typically had the mods done and the street engines from the factory did not. If you build a 2.7 with steel headstuds and no timecerts you very likely will have pulled studs in the future. If you build one with dilivar studs and no timecerts you may get away with it but why take that chance.
-Andy
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72 Carrera RS replica, Spec 911 racer |
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09-14-2009, 01:30 PM
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Join Date: Jun 2008
Location: So. Calif.
Posts: 439
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Tim, This is the way you want to go and I will try to say it in layman terms. This is the case I was going to use to build that 2.7 engine. The 2.7L engine '74-'77, in general, got a bad rap because of the EPA wanting all the smog crap on the motors in the mid-'70s. Porsche did a stupid thing to conform with these USA requirements by placing these "bread loaf" sized thermal reactors (like catalytic conv.) between the exhaust manifolds and extractor. These sat lengthwise next to where the lower head studs (exhaust studs)are screwed into the case. Probably P decided to place the harder studs in about late '77. Engines were dying on people between 70k- 90k miles. The obvious: heated up the engine case excessively; thus the "fine threads" drilled into the case by Porsche started pulling away.........
SO, the fix is to have a machine shop drill out those fine threads and drill larger COARSER threadings for STEEL inserts into the case. In otherwords, inserts with outer coarse threads with the factory fine thread inside them. SO now the head stud will NOT want to pull away because now it's pulling at steel instead of magnesium. And the outer is sunk into case with heavy meaty coarse threads. You don't need fancy expensive studs, just use the factory ones it was made for as long as they're staight and not over heated or cracked in anyway. Hope this is helpful.... in time you'll catch on to things....ask 1000s of questions.... we have all been there. Here are some photos of the steel threads before and after inserted to the case. [IMG]  [/IMG][IMG] [/IMG][IMG] [/IMG]Also, this case is for sale on ebay if you care to see the info; |
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09-16-2009, 04:14 PM
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