I've brought this up before, and I do so again only because it seems
particularly relevant to this thread...
In May, 1973 Motor Trend magazine ran an article about dyno-tuning a
stock TR6. The article is reprinted in the "Triumph TR6 Gold Portfolio"
on pages 114-115.
To summarize, Geraghty Automotive, 4062 Verdugo Rd, Los Angeles put a
stock '73 TR6 on it's dyno and found it to run way too lean with a too
slow advance curve. Their solution was to place the carb needles on a
lathe and through trial and error shape the needles to give a proper f/a
ratio as well as lighten both distributor springs to give a more
aggressive advance curve providing 16* total advance at 3100 rpm. This
process provided an (at the wheel) increase of 14 hp (17 to 31) @ 2500
rpm and 21 hp @ 5000 rpm (50 to 71)!
Geraghty then offered the re-profiled needles and lighter springs as a
kit for TR6 owners.
Geraghty Automotive apparently existed in 2001, as I did a search and
found a site that listed John Geraghty's shop having done some truck
dyno work in 2001.
Could someone in the LA area look Mr. Geraghty up and find out if he
still has the needle and spring specs. for TR6s? And couldn't the same
thing be done for others with similar engine enhancements, such as a kit
for those with Richard Good's cam and 3 carb set-up with 9.5:1
compression? No, each application wouldn't be ideal, but it would get
some of us a lot closer to ideal than where we are now.
My point is, if we invest as a group to have one, two or three different
cars dyno'ed with known specs, we could develop kits with sets of
needles and springs and choose those that most closely resembled our
car's needs. That would be much cheaper than each of us doing it on our
own.
Am I way off here?
Merry Christmas to all!
Jim Davis
Fortson, GA
CF38690UO
-----Original Message-----
From: owner-6pack@autox.team.net [mailto:owner-6pack@autox.team.net] On
Behalf Of Sally or Dick Taylor
Sent: Tuesday, December 23, 2003 6:58 PM
To: Shawn J. Loseke
Cc: 6pack@autox.team.net
Subject: Re: New topic follow up from CR discussion...
Shawn---I started to write a long reply to your post, regarding the fuel
monitor picking up the bump in richness at 3,000. It got so unweildy I
quit writing. There's too much for me to say for this type of forum, so
I'll just hi-lite a couple of things.
Yes, you can find out exactly what part of your needles is responsible
for this increase in richness. You'll need to see where the air valve(s)
are, in relation to leaving the bridge. This area of the needle will
have to be wider. There are temporary ways of "thickening" the needle,
one identified. From there, you can do to the SU chart to see if a
commercial is available.
First, I would "paint up" the needles now being used, to see if these
mods make the monitor show the results you desire. It's very tricky,
because you have to do the same thickening on all three of your needles.
(Unless you have isolated each carb with its own 02 sensor)
For a really good book on this, pick up a copy written by Des Hammill,
on "How to Power Tune the SU Carburetor". (The same principles apply to
the ZS carb).
More on this, if you wish...
Dick
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