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Svobodin
Joined: 08 Oct 2013 Posts: 67 Location: Colorado
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Posted: Tue Sep 24, 2019 12:20 am Post subject: 1980 MY Cylinder head bolt torque question? |
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The factory service manual technical update bulletin for 1980 says that for all cylinder head bolts 1980 MY and up (polygon aka triple square) need to be torqued to 65Nm, then warm up the engine and torque an extra 180 degrees, and retorque after 1000 miles
However, I have hex head cylinder head bolts on my 1980 931.
The torque spec according to the FSM for hex head bolts is 120Nm, and retorque after 1000 miles. Should I follow the hex or the triple square torque spec?
Also, are the Hex head bolts stretch bolts?
I've been told by a good mechanic friend with decades of VW/Audi/Porsche experience that they can be reused, while my other mechanic friend also with decades of Porsche/BMW/Mercedes experience is telling me not to reuse them.... |
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Carrera RSR
Joined: 08 Jan 2010 Posts: 2309 Location: Somerset, UK
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Posted: Tue Sep 24, 2019 8:31 am Post subject: |
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There’s a later bulletin for torquing......
Cannot remember which, Hex or 12 point, but one is stretch and one isn’t if OEM Porsche. Non stretch can be reused but stretch bolts cannot.
Or go for Sierra/Escort Cosworth ARP studs, better clamping on a turbo _________________ 1980 931 - forged pistons, Piper cam, K27/26 3257 6.10 hybrid turbo, 951 FMIC, custom intake, Mittelmotor dizzy & cam pulley, H&S exhaust, GAZ Gold, Fuch'ed, Quaife
Now www.924board.org/viewtopic.php?t=34690
Then www.924board.org/viewtopic.php?t=31252 |
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Svobodin
Joined: 08 Oct 2013 Posts: 67 Location: Colorado
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Posted: Fri Oct 04, 2019 3:32 am Post subject: |
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Carrera RSR wrote: | There’s a later bulletin for torquing......
Cannot remember which, Hex or 12 point, but one is stretch and one isn’t if OEM Porsche. Non stretch can be reused but stretch bolts cannot.
Or go for Sierra/Escort Cosworth ARP studs, better clamping on a turbo |
I do have the technical update, but it does not specify whether they are stretch bolts or not. These are Porsche OEM hex-head studs and are original to the car.
Anyone have any sources? I will be working on the car this weekend hoping to get it running. |
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