[V8] 3.6 vs 4.2 differences

[RockinV8Q@aol.com]

Bore spacing changed requiring a change in headgaskets and head  castings but 
Audi did something that is probably unique among engines of the  world.......
 
 Audi retained the same valve and headbolt locations so the headbolts  are 
offset in relation to the cylinders and its very noticeable on cylinders  
1,4,5,and 8. The same is true with the locations of the valves and sparkplug  holes 
in the combustion chambers and again its very noticeable on cyl 1,4,5, and  8. 
 
 Audi also retained the same camshaft design, with various different  actual 
lobe profiles, through the remainder of the 32 valve engine  run.....meaning 
any 32v cam set will interchange into any 32v engine. There is a  catch though, 
PT and ABH exhaust cams have an offset grove at the back to ensure  correct 
indexing of the distributors, on direct fire exhaust cams the grove is  not 
offset.
 
 It would be interesting to have the cams profiled and see what is  what. ABH 
and PT engines use the same exhaust cams but the intake cams are a  different 
story, PT Auto, PT Manual, and ABH are all different.Its know for sure  the 
ABH has more lift but duration and overlap are unknown.
 
KT