Re: .02 oops .20

[Scott Fisher <sfisher71@domain.elided>]

--- John Hertzman <johnhertzman@domain.elided> wrote:
> Scott Fisher is a marvelous proofreader, among his
> many other sterling qualities; 

Thanks -- years of reading and publishing technical
documentation have apparently left me with at least
one useful skill...

> I probably should also note that the shorthand use
> of the first five digits-
> 105.48, 105.20, 105.02, conceals one other boobytrap
> besides the risk of
> transposition; there are two 105.02s, the
> 105.02.03.200.00 and the
> 105.02.03.200.01 which differ appreciably.

Ah -- they surely do that!  

105.02.03.200.00 is (per Centerline) listed as
applicable to the 1600 Normal and early 105 series;
the 105.02.03.200.01 is listed as 1600 Late 105, 1300
105, early 1750 Euro and 1750 FI.  The most obvious
difference is 0.4mm of lift, with the later cam having
9.5mm and the early ones 9.1mm.

An even more subtle confusion lurks for the unwary in
the Centerline chart, which includes two separate
specifications for the 105.02.03.200.00 cams.  While
duration and lift are the same for both listings,
valve timing, overlap, and lobe centers are different.
 It took me several minutes to realize that the
differences in valve timing and overlap were the
result of using two different lobe centers -- 114
degrees for the 1600 Normal and 102 degrees for the
early 105 series.  

So, does anyone have evidence (timeslips, dyno sheets
preferred) on the effect of runing a 1972-74 2L with
the 10520 (US) cams at 102-degree lobe centers
(instead of 114 degrees intake/102 exhaust), like the
10502...1 cams?  Or the 99.5 degree lobe centers of
the 10548s?  Were these timing values tested by
Vandenberg?

Or should I try these out and report? :-)

Best,

--Scott Fisher
  Tualatin, Oregon
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