Hi, Mark---The back pages of the Haynes Manual for the ZS carburetor
shows the available needles. You can see from the different needle
tapers which ones might give you the leaner a/f ratio you're looking
for. Contact Burlen Fuel Systems at:
info@burlen.co.uk
to be sure these are the biased needles that fit right in to the air
valves, without any mods. Or make the mods!
Loose throttle shaft bushings tend to let in unmetered air, which causes
a lean mix, unless the needles are raised to compensate.
It's tough to come up with the right needles, using the
seat-of-the-pants method. Performance cams require more richness at idle
if you want a reasonable idle, but this doesn't ensure the ratio to be
right further up the range. I always suggest using a (tail pipe) gas
analyser, or an 02 sensor with an Air/Fuel monitor, to get a true
picture at all engine speeds.
Dick
K&N A/F Monitor
Bosch 02 sensor
From:
mhooper@digiscreen.ca(Mark Hooper)
Subject: Stomberg needles
Is there a chart anywhere for Stromberg needle choices? I have a warmed
cam and 1.75 roller rockers. Definitely running too rich and can't get
the adjustment right. It seems to be a needle issue, although the
carbs probably need re-bushing too.
Cheers,
Mark
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