RE: Ur-Q hydraulic head conversion questions...

["Bruce Bell" <bbell04@ibm.net>]

Interesting, This would indicate the 5 cyl. head underwent a different
development process from the 4 cyl. VW.  Check the differences between the
valve centers for a given cylinder.  During VW development this distance was
increased by about 1 mm to prevent cracking between the seats and as a
consequence the combustion chamber grew slightly in size (30 cc from 25 cc).
Of course, the early VW heads didn't have the large valve sizes of the WR/WX
motors so the CC size may the same/similar to accommodate.

The first VW heads to see these changes were the '83/'84 solid lifter GTI
heads then all the hydraulics.  At the same time some of the water/oil
passages were moved.

My assumption had been that 5 cyl. heads had a similar migration due to the
reported cracking between the seats of the early Urq. Phil, can you shed
some light on this? Are the MB motors any less susceptible to cracking than
the earlier WR/WX?

Bruce

> Yesterday, I compared my Ur-Q's original cylinder head with
> an MC head that I
> purchased from Chris Semple to use as a core.  I even went so
> far as to
> compare chamber volumes and so far as I can tell with my uncalibrated
> equipment -- all the good stuff is still packed away from my
> move last fall
> -- they are virtually identical.  Even the oil and coolant
> passages line up