[s-cars] Is taking the head off difficult?

[mlp]

FWÏW, I believe ARP now makes a head stud conversion kit for the AAN.

OTOH, the stock Audi AAN head bolts are reputed (except perhaps only for
Happersize  applications) to be da Bomb!

I think (that's think only, cause one would want to double, &/or triple
check this with ARP's technical folks) the principal advantage to the stud
kit may be that you can put a head on and take it off again more than one
time,....

But then I don't think that's a feature Ed (or most of us) really want to
take advantage of, or test out.

ARP will of course claim that their studded application will be stronger,
but I doubt the claim will be based on an side by side comparison testing.
As Igor (?) posted on the "before" and "after" length measurements, I am
pretty sure that once the head has been torqued & then retorqued to spec,
you don't want / shouldn't re-use the bolts.  Isn't there a paragraph to
that effect in the Bentley somewhere?

My personal experience had been that there can be, in fact has been some
considerable differences from machinist to machinist in terms of valve job
efficacy, and "advice."

In particular, has anyone (apologies in advance, I saw Anna Nicole Smith on
the Jay Leno show last night) ever delved into "How fat my contact seat
(particularly on the exhaust side) should be, can be or must be?"

I think (heck, I know) potential flow varies considerably, especially on the
exhaust side, with how that critical portion of the valve & seat are cut.
And while "narrower" and positioned as close to the outside radius of the
valve face is usually optimal for flow purposes, the belt & suspenders
builders in crowd worry about heat transfer etc.

Second, you flow characteristics (again, especially on the exhaust side) can
be dramatically affect by whether or not the tulip on the stem side is back
cut to one degree or another.  As seen very mixed and conflicting advice /
stories as to whether this is an advisable, or acceptable practice with the
AAN components.


mlp