Unfortunately I cannot give an all-encompassing table of what needles are needed for which engine builds. My life's collection of all the automotive-orientated work I'd ever done was stolen out of my car by some low-life scum a few years back. Not for what it was - but for what it might be. All I have is a few scribbled notes, the source of where I start now. Being an oft-voiced question on the message board, I thought I'd share it with you. Since there is already a very good source of starting points/applications for fixed needle carbs, this is for those floundering about in the wilderness that is the biased (swinging) needle example of the breed.

These are based generally on 1275cc+ motors, using a reasonably modified head, compression ratio on the sane side for unleaded road use, and uses Kent Cam profiles as the main guide so just select one that near-matches what you're using.

 

Standard Filter Case with K&N filter

      		 K&N Cone or Pancake filter

Single 1.5"

 

 

MD256

AAK

AAM

MD266/7

AAA

AAM

MD286

AAM

ABY

 

 

 

Single 1.75"

 

 

MD256

BDL OR BAK

BDK

MD266

BDK

BCE

MD 276/286

BBC

BBC

MD296

Modified BBC...........

...........

 

 

 

Twin 1.5"

      

(assuming K&N pancakes or no filters)

  

MD256/266

AAV

 

MD276

AAA

 

MD286/296

AAM or ABY (ABY is richer towards top end).

 

Other references -

 

These are for comparison and are arranged going from leanest to richest. Makes a good visual example of what happens where on the needle profile in accordance with engine specification when the profile list of each is lined up in a row.

BEJ Standard unleaded Metro.
BER 1.3 Pre-injected Cooper (basically MG Metro spec engine).
BFA Alternative Metro Turbo needle, has richer cruise section, but leaner top end.
BDD Metro Turbo standard needle.
BFY 1.3 Pre-injected Cooper unleaded (basically MG Metro spec engine).
BDL MG Metro standard needle.
BCE Popular modded engine needle (see above table).
BBW 1.3 Pre-injected Cooper with Stage One kit using K&N cone/pancake filter.
BDK 1380 fast road spec (MD286, modded head, etc.).

NOTE:

When choosing a different needle, select one with the same idle figures. If this is not possible, remember -

If new needle has a leaner idle figure, the rest of the needle will give a slightly RICHER mixture than the profile suggests.

If new needle has a richer idle figure, the rest of the needle will give a slightly LEANER mixture than the profile suggests.

This is caused by re-positioning of the jet to get correct idle mixture.

Like I said - these are merely starting points - so a healthy dollop of sensibility is needed! I highly recommend buying the SU needle chart book available - part number ALT9601. Not only does it list all the needles and their profiles, nut a useful section in the front giving suggestions on how to select a different needle than the one you're using.