Don--- If the "button, or knob" you are referring to is near the top of
the needle, this is the needle height adjustment screw. It has the
O-ring around it to keep the damper oil from falling thru.
If you are referring to the one at the side of the needle, it is keep
the needle case from rotating, during height adjustments. This is a
spring-loaded, threaded plunger, which is meant to enter the keyway in
the needle case for adjustable needles. Being spring-loaded, height
adjustment can be made without loosening this screw.
Obviously, non'adjustable needles do not have the same "case" around
them. Rather they have a bushing to support the needle shank, and a
simple setscrew to hold everything in place. Know that this style CAN be
adjusted for idle mixture strength, by loosening the set screw and
moving the needle up or down. (So can the ones for the SU carburetor)
The B2Y needle, if I understand Berry Price's installation of these in
his own TR6, is the "non-adjustable" kind. He made his adjustable by
using the adjustable JET, as found in the earlier 250 and TR4 ZS
carburetor. We know that adjustable jets perform the same duty as the
adjustable needles, but in a different manner. You MAY already have
these adjustable jets on your 250 carbs!
There should be I.D. markings on all needles for both the SU and ZS
style.
Vance may be able to tell you what is involved to insert the B1E needles
into your adjustables.
Dick
Don wrote:
triumphs@autox.team.net Subject: Dick and Vance -- ZS needles
Hi,
I guess I need some education.
I've never disassembled a ZS carb or removed the needle from the carrier
so keep that in mind.
I do however have the old thin Haynes ZS manual with the tables in the
back and also Nelson's carb descriptions.
My TR250 engine will be at 9.5:1 CR and I will have a Integral Cams
Stage II 274 duration cam with Roller Rockers and .425 valve lift. I
believe I need richer needles in my ZS carbs for this. At least that's
what Joe Curto thinks.
In Part 3 Appendix 1, Applications List, of the Haynes manual lists a
B2Y blue needle for the TR250. Appendix 2, Metering needles, section
says this needle is adjustable. I assume that is an error? yes/no? It's
really non-adjustable?
Joe Curto gave me a Jag B1E needle which Appendix 2 Metering Needles
says is adjustable.
OK the questions....
In all the cut away drawings it appears that there is a button or knob
on the carrier end of the needle. These Jag B1E needles I have from Joe
Curto have no such "button" end. It's simply a straight smooth shank. I
have lots of ZS carbs most with 3385 or 3337 brass tags which are listed
in the Haynes manual as 71/72 vintage with B1AF adjustable needles. I
will use these carbs rather than my non-adjustable original TR250 carbs.
Is it simply a case of removing the B1AF needle from it's adjustable
carrier and inserting the Jag B1E needle? There are no markings on these
B1E needles. Is that typical? What about this knob or button I see on
the carrier end in the cut away drawings?
Thanks,
Don Malling
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