[s-cars] Re: Valve Job Anyone?

[Kirby Smith]

The convenience factor may be a sufficient one, although not the factor
used to sell the ARP studs.  Convenience raises a question in my mind:
Is it significantly faster to remove and re-install an Audi head using
studs rather than bolts?  This might matter to a race team.  While I
haven't done an Audi head, I've done Corvair heads, which are retained
by studs (very long ones).  Without an engine stand, I can't imagine
getting a head back on with bolts.  I presume this is also true of air
cooled Porsche engines.  But both these cases are somewhat removed from
the Audi configuration.

kirby



QSHIPQ at aol.com wrote:
> 
> Dave:
> Thanks for your post.  A couple things.  First, industrial deisels are going
> to use studs more for the low volume and specific application than
> "necessarily" strength advantage.  Most industrial diesels also use a steel to steel
> mounting (many times without even a gasket), which will squirm much less than a
> cheap cast aluminum to steel mounting.  I also see two torque install values,
> one to land the stud, the other to land the nut.  Make a difference?  I don't
> know.
> 
> Again, it's a problem vs solution.  Multiple use of a stud isn't a "solution"
> that's a convenience if anything.  A solution might be increased clamping
> force, but that's not proven (yet)on these applications (IMO):  As a problem OR
> as just a fact.  Do we even know what the comparative tensile strength is
> between the stud and the bolt?  I don't.  Do we know that increase clamping force
> is necessarily a *good* thing on a cheap aluminum head casting?
> 
> WRT hydrolocking, I've never btdt, as I'm pretty anal about threading
> procedures.  This includes proper cleaning of the threads in the block with
> compressed air.  A battery brush with rustbuster agent makes a great thread cleaning
> tool.   I've heard the stories of hydrolocking bolts many times, the good thing
> is, most folks that have "hydrolocked" a head bolt/stud have an 'n' of exactly
> 1.
> 
> Industry "conventional" wisdom is ok to follow, IF we present a problem
> argument.  Since we haven't presented that at all (Hap maybe = 1) in any context or
> claim, my questions still remain unanswered.  All race teams use them, and
> all industrial diesels use them.  Ok, I am still looking for more.  I'm not
> necessarily a disbeliever, the majority of my job is to identify and correct
> problems with audi quattros.  I see neither a head bolt or stud "causing" one, in
> which case, to me it comes back to a known entity.  Replace bolt with new, call
> it a day.  If a head gasket blows, fix the problem, replace the head bolts
> with new, and call it a day.
> 
> Scott Justusson
> 
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