John:
Z-S pistons, unlike those of SU's, are not matched to the cylinder and thus are
interchangeable. (That's because the seal is created by the rubber diaphragm,
and not just the perfectly matched piston.)
If your mixture is horribly lean, you've got air coming in from somewhere --
from the throttle shafts or a poor hose connection(s).
--
Martin Secrest
72 TR6
73 GT6
John Jacobsen-Watts wrote:
> Listers:
>
> Are Zenith Stromberg air valves (the piston w/ the adj. needle in it)
> interchangeable between carbs? What do the numbers in the air valves mean
> (12, or 13)?
>
> There is some useful content in this mail, but mostly I'm kicking myself.
> Car ('74 TR6) ran beautifully, dwell/timing/carbsynch etc. spot on, but
> running lean as evidenced by lifting air valve in carb (~1/4") and noting
> severe drop in idle. PO had stripped the hex head (not threads) in adjusting
> screw for needle, so I pulled both air valves and set needles manually by
> sight such that needle delrin washer flush with bottom of air valve when I
> rebuilt the carbs 5 years back. To remedy this problem, I purchased a used
> air valve complete with adjusting screw and spider washer inside. Put my
> original adjusting needle into this used air valve and adjusted needle
> height to match other "good" carb in the car.
>
> The result? Horrible running condition. I am now in the process of going
> back over everything. My question is are air valves matched to bodies, and
> should they never be separated? Only difference, other than air valve, is
> that I am now putting the carb suction covers back on "correctly", so that
> the rib on the suction cover body sits towards the air cleaners, as per pix
> in the Bentley manual.
>
> Thanks in advance for you replies,
> John
> johnw@wrq.com
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