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1980 MY Cylinder head bolt torque question?

 
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Svobodin  



Joined: 08 Oct 2013
Posts: 54
Location: Colorado

PostPosted: Tue Sep 24, 2019 1:20 am    Post subject: 1980 MY Cylinder head bolt torque question? Reply with quote

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: 1840
Location: Somerset, UK

PostPosted: Tue Sep 24, 2019 9:31 am    Post subject: Reply with quote

Thereís a later bulletin for torquing......
Cannot remember which, Hex or 12 point, but one is stretch and one isnít 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
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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
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Svobodin  



Joined: 08 Oct 2013
Posts: 54
Location: Colorado

PostPosted: Fri Oct 04, 2019 4:32 am    Post subject: Reply with quote

Carrera RSR wrote:
Thereís a later bulletin for torquing......
Cannot remember which, Hex or 12 point, but one is stretch and one isnít 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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1980 Porsche 924 turbo M471 (Project)
1983 Porsche 944 (Daily)
1984 Porsche 944 Sunroof delete (Project)
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