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Engine stud, what type to buy + shims
Posted: Fri Apr 07, 2017 5:08 pm
by Jimmy
Folks
Currently undertaking an engine rebuild, have machined the case where the barrels sit as they weren't flat. The studs removed (retaining the cylinders in-place) have seen better days so am replacing these. Looking at the standard Porsche studs, are these recommended?
Having machined 0.007" off the case, are shims required (effectively replacing the 0.007" removed) to get the clearance needed between TDC and the valves. If so, are the shims available and from where?
Car 1968 911 (changing from T spec to S pistons / cylinders with an E spec cam)
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Jimmy
Re: Engine stud, what type to buy + shims
Posted: Sat Apr 08, 2017 2:09 pm
by Jimmy
Any thoughts on whether I have to add a shim to each cylinder?
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Jimmy
Re: Engine stud, what type to buy + shims
Posted: Sat Apr 08, 2017 6:56 pm
by MikeB
You will fit a copper gasket between the base of the cylinder barrel and the case, the smallest thickness is 10 thou (0.25 mm) you can use these in various combinations to adjust the height of the barrels. In your case, as you are fitting different pistons, you need to do a test build to see how many you need to fit to give the required clearance.
https://www.rosepassion.com/en/cat/pors ... 79/P116582
You get a set of 6 in a gasket set
Re: Engine stud, what type to buy + shims
Posted: Sat Apr 08, 2017 8:02 pm
by Jimmy
Perfect - thanks Mike
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Jimmy
Re: Engine stud, what type to buy + shims
Posted: Sat Apr 08, 2017 8:48 pm
by MikeB
Jimmy
If you haven't got it, this is THE book you need
https://www.abebooks.co.uk/book-search/ ... 760310878/
Re: Engine stud, what type to buy + shims
Posted: Sun Apr 09, 2017 5:45 pm
by acclassics
+ 1 on mike,
dont guess on the shims, you need to measure deck height, and piston to valve clearance, then decide what size shims you need, especially with the S/E specs your going for. You will do trial build of top end, then final build with sealants
Another good book is by Cole Scrogham, he talks in detail about the piston to valve clearance
https://www.abebooks.co.uk/servlet/Book ... 6an%3Dcole
Waynes is really good (the link in mikes post), but it does have errors, especially on some of the torque settings, so you need to also follow his website he put together which lists the corrections (see below). A really good read for sure.
http://www.101projects.com/911-Rebuild/corrections.htm
Others also disagree with everything that is written so always consult more than one source, including the genuine porsche workshop manual, that should always be the first point of reference, other books after such as Bruce Andersons(performance manual), Cole Scogham, Wayne Dempsey, Haynes, Etc :
Re: Engine stud, what type to buy + shims
Posted: Sun Apr 09, 2017 6:53 pm
by Jimmy
Many thanks - 'Porsche 911 Engine Assembly Guide' now ordered.
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Jimmy