[s-cars] Camshafts & Cylinder Heads - whole lotta questions

[Manuel Sanchez]

Fellow S-heads,

I am looking for general feedback regarding cylinder head work and  
camshaft options for our AAN engines, as I am starting to investigate  
options for a possible freshening of the cylinder head of my mostly  
RS2'd wagon.

The prospective patient is  a mostly RS2'd engine (basically  
everything is RS2 except I still have the stock AAN intake & exhaust  
cams) with 137,000 miles.

I believe in reading some old posts that there has been some  
discussion that rebuilding the head is better left until entire  
engine rebuild time. Is this a fair statement? My memory can  
sometimes be faulty (according to da wife).

I also think I have read that porting & polishing does not really net  
you much of a gain. Again is this fact or fiction?

Regarding camshafts, I believe I have also read that a reasonable  
upgrade is to install 7A cams. The standing question of is this a  
good idea still stand of course. Other questions are, is this upgrade  
mean installing both cams or just one of the 7A cams?  Would I use  
the AAN sprocket or the 7A Cam gear (the one connected to the timing  
belt)? Browsing the interwebz, I have found references that you  
should not just install the 7A cam(s), that you need to change the  
valve springs because the stock AAN springs are not up to the task?  
Anyone know if this is true?

Cylinder Heads: I have read a little that suggests there is likely to  
be some cracking, particularly around the spark plug holes, of AAN  
cylinder heads. I think that some cracking in this area is "OK"  
according to the manual, I don't have the pertinent passage at hand,  
but I think I have read you can have cracks that are XXmm long. Is it  
advisable to rebuild a head that has cracks that fall within the  
permissible range, or are you better off finding a different head?  
034 in particular recommends using naturally aspirated 7A heads,  
which due to their life in non-turbo applications are less likely to  
have cracks. I understand that the water manifold openings in the 7A  
head requires some machining to align with the AAN water manifold,  
but is there something else required to allow a 7A head to work on an  
AAN block? Cam position sensor mounting?

My goal is currently to remain at RS2 levels, although should I win  
the lottery I suppose I might peer down the beyond RS2 abyss. Once I  
get my fuel line fixed I'll be looking into more current compression  
& leakdown numbers for the engine. At a minimum I may be looking into  
a headgasket replacement, which will require all sorts of gasket  
replacement and new head fasteners. In the "while we are in there"  
vein of thought, I've wondered about what are the other options I  
should look into.  Based on this preliminary diagnostics I'd also  
like to know if it makes sense just to replace the headgasket,  
fasteners and install some camshaft(s) on the minimal side of things,  
all the way toward a complete head replacement.

I have lots of questions and am looking for the more knowledgeable  
info that the list community has to offer.

As always, thanks in advance.

Manny
95.5 urS6 Avant (currently pissing fuel, well not really, since its  
parked under a tree)