Don,
When I communicated with Peter Cox of Moss Triumphtune some months ago he
brought up the SU vs. ZS decision and referred to the metering choices on ZS
carbs as "pathetic" when trying to optimize carbs to more agressive cam
profiles.
Now that is not to say the ZS carbs are incapable of performing to a higher
level of performance. I think Richard Good would have a few words to say
about that. And the first time I saw an SU carbed TR six was Steve Rossi's
250 back in 1976. His opinion was the same - the SU's are far more
'tune-able' because of the greater needle and jetting options as opposed to
what you can do with ZS carbs. Although not knowing Steve all that well at
the time he definitely seemed to know what he was talking about. At the
time he was also running a factory S-2 cam and velocity stacks. I was just
a neophyte at the time trying to absorb as much as I could about my newly
acquired TR and he was more than willing to talk Triumphs.
Why then is the SU conversion not as prevalent in the US as one might think
given its advantages? Maybe the "if it ain't broke, don't fix it" mentality
holds us back. Maybe the cost of a fully prepped pair of SU's holds us back
($300-$400+ I believe). Plus understanding the "new" carbs that have much
more flexibility than the ZS in areas that ZS carbed owners never had to
deal with. Maybe pollution control regulations in certain states make us
leery? Or simply what we don't know doesn't bother us. You know, ignorance
is bliss.
It does not seem limited to modified engines. I've heard of owners with
otherwise stock TR6s make the conversion and rave about it. But frankly,
you don't hear of too many new car owners complaining of or otherwise
disliking their just purchased cars. So maybe we just convince ourselves
that after the blood, sweat, tears and money we 'see' obvious differences no
matter how slight. I would think the real benefit though is in a modified
engine that includes extensive head work.
So I do not think it is as much a difference in opinion. There seems to be
general agreement in the advantages of SUs. It's just that U.S. owners are
apparently not as inclined to pursue this conversion, most probably due to
the perceived lack of need based on the limited engine mods of most road
worthy TRs.
Greg Dito
CD6250L
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