[Supras] Question about head gasket (hopefully last)

[theOnly_way2FLY]

They switched to metal head gaskets.  Period.

 
 
Mike Lewitz
Phoenix, AZ
Supra - the only way to FLY!
==========================
 
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-----Original Message-----
From: supras-bounces at supras.com [mailto:supras-bounces at supras.com] On Behalf
Of berniek at technicaldevelop.com
Sent: Sunday, June 04, 2006 3:25 PM
To: Craig Thommes
Cc: Supras at supras.com
Subject: [Supras] Question about head gasket (hopefully last)


Inline 6 cylinder engines are probably the longest which use aluminum heads
and iron blocks.  Other engines have shorter heads, which minimizes
cumulative end to end differential expansion or head warping.  Most 7M
gasket problems happen at the sixth cylinder, apparently due to cumulative
differential expansion.  My JDM engine showed deep grooving in the head and
block around the stock gasket crimped rings, especially at the ends,
presumably from tendencies of the block and head to "walk" with respect to
each other due to thermal cycling.   

I do not want to add fuel to a flame war here.  I just want to know what the
consensus is regarding life to be obtained from a 7M with a Cometic gasket
(mine was special ordered as 2 mm thick).  I'll be running 14 PSI boost and
ARP head studs.  I'd like to be able to get 150K miles with periodic
retorquing if needed.  Got that from the stock head gasket with 72 Lb-Ft.
retorquing at 8 PSI.

Just out of curiousity, what did Toyota do in the 1J and 2J engines to
eliminate the problem?  

Thanks.

        BernieK
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