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Doodle

Got the head back from the machinists. Good news. It isn't warped. So they performed a valve grind and installed new valve stem seals and two used inner valve springs to replace the broken ones and pronounced the head ready for re-install.

Since the original problem appears to have been a stock Fel-pro head gaskets failure to contain 180 to 200 PSI of compression I've opted for the Cometic MLS head gasket this time. Anything special I should know about installing it? Cometic's instructions indicate to torque to manufacturer's specifications. I have a set of new Porsche head bolts for the '77 to '82 model years. Has anyone used these instead of the Raceware studs? Any suggestions for what the final torque should be on these bolts? Use the Haynes figure of 72Ft/Lbs cold and 86Ft/Lbs warm? Are these bolts torque to yield type?

Any info from experience here would be helpful. Otherwise I'll use best guess or when all else fails, follow manufacturer's instructions.
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Doodle
Pre 77.5 Mars Red

emoore924 · Joined: 13 Apr 2004 Posts: 2815

I don't think the install is anything overly complex. Not sure what bolts you got but whether they're stretch bolts or not should come from your parts source -- that'll tell you whether you need to do that +1/4 turn thing or just take them to the factory spec (...in three stages and in the proper tightening sequence of course). I think both types were available from the factory but I don't know when/if they changed types or how to tell. I believe one way is to check the head of the bolt -- one type is hex, the other, 12-point, and the neck of the bolt is different too..., sorry, I know this isn't helping much. I'd say call Porsche and ask them what they gave you

Haynes is pretty good. 86 ft/lb warm is correct IIRC.

Doodle · Posted: Fri Aug 07, 2009 8:42 am Post subject:

Thanks emoore924. I've got the 12 point socket head bolts. I guess I can check with the dealership to see if they are torque to yield.
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Doodle
Pre 77.5 Mars Red

Brockoli · Posted: Fri Aug 07, 2009 9:01 am Post subject:

thats sweet that your head isnt warped, mine is sometimes

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'80 924 M471,Wideband O2, Full coilover susp,23/19 sways,Bilstiens,KLA Strut Brace,Roll Bar,Test Pipe,BBS RS, Willwood BBK

25% of a '87 944 Chumpcar http://straightpipe.ca/forums/showthread.php?t=2454

'79 924 Sebring Edition(Sitting)

Chrenan · Joined: 15 Jan 2003 Posts: 3903 Location: Canada

Doodle · Posted: Fri Aug 07, 2009 4:33 pm Post subject:

Chrenan, I have a well worn Haynes Manual that has served as my reference for a number of years so would definitely be interested in having a look at the factory service manual this time around.
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Doodle
Pre 77.5 Mars Red

Chrenan · Joined: 15 Jan 2003 Posts: 3903 Location: Canada

PM sent, check you inbox...
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1987 951 - M193 Version for Japan

Rocco R16V · Joined: 03 May 2009 Posts: 497 Location: PNW

I see you already have new head bolts, so just some info for everyone.
From what i've heard, all factory head bolts are one time use.
ARP bolts/studs have a great rep and are reuseable, not one time use stretch to yeild bolts. When I rebuilt my vw motor i used ARP head studs, rod, and main bolts. just a little more expensive than stock items and IMO much better.
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"Government exists to protect us from each other. Where government has gone beyond its limits is in deciding to protect us from ourselves. "
Ronald Reagan

ideola · Joined: 01 Oct 2004 Posts: 15548 Location: Spring Lake MI

Actually, the ARP head bolts are cheaper than stock at $130 street price for a complete set. I got mine from Summit, and they regularly run specials, I happened to get mine when they were offering $30 off orders of $100 or more, so $100 + shipping. The part number will show up as for a Cosworth application, but we have multiple confirmations that they are a direct fit for the 924 head: part number 251-4701.
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erstwhile owner of just about every 924 variant ever made

Rocco R16V · Joined: 03 May 2009 Posts: 497 Location: PNW

Thanks ideola, i am moving up to porsche from vw and dont really know alot about porsche part prices, except that they are usually more

the ARP vw prices are almost identical to stock items. ask anyone who has used them, they are much better than stock. They also offer undercut studs for people who have decked the block or resurfaced the head for more compression.
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"Government exists to protect us from each other. Where government has gone beyond its limits is in deciding to protect us from ourselves. "
Ronald Reagan