Dropping the jets richens everything across the entire
throttle range.
Needle taper changes, vary different portions of the
throttle range.
Different needles may be set to identical idle mixture
(jet/bridge height) ratios and run just fine at idle,
but open throttle or cruising setting may be too rich/lean.
Hence, the reason for different tapers to the needles.
The richer/leaner needle specs you see listed in books
are for elevation changes, not throttle position mixture
accuracy requirements.
Check out http://www.teglerizer.com/mgstuff/SUcarbs.htm
and compare the various needles used in the different
carbs over the years. On that page is a link to the SUNEEDLES
program that helps you identify what needles to use.
You can use it to compare the difference in the needles
listed on the chart on the above mentioned link.
Paul Tegler ptegler@gouldfo.com www.teglerizer.com
----- Original Message -----
From: "Bud Krueger" <bkrueger@ici.net>
To: "MG List" <mgs@autox.team.net>
Sent: Tuesday, March 06, 2001 10:21 AM
Subject: Richer Needles vs. Jet Adjustment
Hello knowledgeable ones,
Eric just talked about having the 'richer #6 needles' for his
carburetors. My Haynes carburetor book would seem to imply that he has HS4
AUD135's whose standard needles are #5. My question is, "When should one
install richer needles, rather than simply back off on the jet adjustment?"
To paraphrase Ed, "puzzled minds want to know".
--
Bud Krueger
http://home.ici.net/~bkrueger/
52TD
77MGB
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