On 20 Apr 2004 at 23:09, David Griffiths asked:
> Is it common (i.e. normal) to have the air flow synched at
> idle but different at various rpm's, and if it is considered
> abnormal what might this indicate and what should be done about
> it?
> >From: "Randall Young" <ryoung@navcomtech.com>
> >The Uni-syn will only tell you if the
> >carbs are synchronized at idle, not if they stay
> > synchronized as you open the throttle.
Far be it from me to disagree with Randall! He is right that it
syncs (synchs? psynchs?) the carbs only at idle. However it can be
applied to part throttle a bit if you try hard enough. The question
you ask is why they'd be unsync'ed in the first place. Depending on
your carb linkages, the relative amount that the carbs are opened by
the throttle depends on how the linkage at each carb is locked to the
common shaft that runs between them. The linkages are typically (and
for all I know, always) attached by clamps tightened down by small
bolts and nuts, some odd size like 5/32nds or something like that.
If you loosen one of the nuts, its clamp will spin on the shaft. The
trick is to get them set and locked down such that they open their
carbs the same amount. The Uni-syn can be used to judge the higher-
than-idle openings if you can find a way to open the throttle until
you get medium-to-high revs and keep it from moving while you swap
the Uni-syn from carb to carb. It requires some creativity, perhaps,
or three hands.
The hard part is getting the carbs sync'ed if you find them not. It
means loosening one of the clamps (but not too much), twisting it on
the shaft just the exact right amount, then locking it down. If
you're lucky, your linkages may even have adjusting screws! Nah, I
doubt it. Start by getting them at least close or the job may be
really difficult. On the other hand, if you ever remove the carbs or
for any other reason get the linkages screwed up, you'll have to go
through this procedure anyway.
Just my $0.007.
Got a driveshaft back from the machineshop yesterday! I'll put it in
this weekend and the GT6 should be smooth (finally)!
--
Jim Muller
jimmuller@pop.rcn.com
'80 Spitfire, '70 GT6+
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