John,
You've just hit on the reason many enthusiasts prefer SU's to Z-S's:
the availability of needles. Both carbs work on the same principal, and
perform equally well. There are just more needles available more cheaply
for SU's than Z-S's. I use Z-S B1E needles on CF38690 from a 68 4.2
liter Jag E type. Got them from Joe Curto (sp) on his recommendation.
There is a reprint in the book, Triumph TR6 Gold Portfolio, of an
article that ran in the May '73 Motor Trend titled "Triumph on the
Dyno". It describes how a company in Los Angeles, Geraghty Automotive,
recurved the distributor and turned the needles in a lathe using trial
and error to increase the HP at the wheel from 50 to 70 at 5000 rpm on
an otherwise stock TR6. That's a 40% increase! Somewhat surprisingly, CO
and hydrocarbon emissions where reduced at idle and CO was reduced 25%
under load. Geraghty offered a kit of weaker advance springs and custom
profiled needles for $25.00. Any left coasters here of this Garage? The
location is listed as 4062 Verdugo Rd.
The above mentioned TR6 Gold Portfolio is interesting and informative
reading, giving insight into what contemporary writers thought about the
TR6. A warning: most weren't impressed.
Jim Davis
Fortson, GA
CF38690UO
CF37325U
Day.John@fin.gc.ca wrote:
>
> One thing I've always been curious about - with all the effort to get more
> air into a 2.5 TR6 engine, how did Jaguar ever manage to get their 4.2
> Series II E-type to breathe with twin 175 CD2 Zeniths (compared to the
> triple HD8 SU's of the 3.8)? - REMOVE the needles? I know the performance
> wasn't the same, but not by a whole lot. Just curious, but there must be an
> easier, cheaper way to get some oomph out of the standard iron lump than
> 'bigger this' or 'triple that'. Has anyone fiddled with different needles?
> How 'bout a mild regrind and a few thou off the head (converting to no-lead
> while the head is off, since you're in there already)? Cheers, JD
>
> -----Original Message-----
> From: Jim Hill [SMTP:Jim_Hill@chsra.wisc.edu]
> Sent: December 8, 1999 11:01 AM
> To: 'Bob Lang'
> Cc: Triumphs@autox.team.net
> Subject: RE: Carburettors
>
> Bob Lang wrote:
>
> > There is another option, that I forgot to mention... some folks
> use twin
> > HS8 SU's - you need to modify the manifold or make an adapter, but
> these
> > will flow a lot more than the HS6's...
>
> Has no one ever tried a triple HS8 SU setup?
>
> Jim Hill
> Madison WI
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