In a message dated 98-10-10 18:19:14 EDT, Uwe.Ross@pobox<img src=/i/dc.gif border=0 width=35 height=15> writes:
<< BTW, I was stunned to see that this 12/97 production date VR6 had dual valve
> springs. All my and Techtonics' info pointed to single springs. I told the
> customer the install would be aborted if we found single springs, but he
> insisted on the exploratory surgery. He won out this time. So it seems like
> all you 98 owners out there can go ahead and make cam plans without fear now.
OK, so what's the bottom line... Are there *any* VR6's with single valve
springs? And if there are, why does this preclude a cam isntallation?
Can't you just replace the single springs with the HD (diesel?) double
Whether or not the single valve springs indeed exist remains to be seen.
According to the VW microfiche, the 98 model year got the single springs,
which has proven not to be the case so far.
The single springs test out to be around 100lbs, which is not sufficient for a
high lift cam like the 268s. Higher rpms can result in valve float and piston
contact. The dual springs have an effective rate of 150lbs, and the TT HDs
are about 200lbs. When doing cams of 11mm or more lift, I prefer to replace
the valve springs. It's a clearance issue which the TT spring design
rectifies. I also like the added spring pressure.
The concern of updating the single springs resided in the head design and
whether or not there was an inner seat machined. The VR6 head does not use
seat shims like most other heads, and rather the springs sit right on machined
lands. If the inner land is not there, an inner spring cannot be added.
Apparently, Techtonics had info that the inner spring seat was there, and all
that was needed was the addition of an inner spring and appropriate retainer.
No big deal afterall, and now a non-issue as that the 98s seem to come stock
with dual springs. Anyone with contrary info?
Air & Water
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