H4 needle advice

[fred1380]

hi all,

i need some help for choosing the needle for a pair of H4,

the engine spec is

1293, kent 286 cam, 1.5 rocker, stg 3 head, lcb, rc40, straight cut gearbox and drop

at the moment i have some CP4 and BG but open to other advice for starting point

[Frogeye61]

I have a copy of WinSU which I think isn't too bad.
Staying with only rich needles it suggests ACC, GX, CF, ADY
Allowing a bit of lean at top end BS or ABK
The program only costs 10 but is only for one computer, and now I have to trade this one on

[fred1380]

have just check the yellow book, for 1275 with modified head and semi race cam it say red spring and n°3 or 4, any other opinion?

[carbon]

Most factory twin 1.5 SUs used the blue springs. Also need the right damper rods (might be 8014?).

CP4 needle was specced for the 970, you might be better with either 7's as used for one of the 1275 BL-ST twin HS4 kits or MME (richer).

[66S]

I'm running 6's and they feel quite good but I've yet to check the air/fuel ratio. I have tried CP4's and BG's but no good.

Al

[fred1380]

thank you for the comments, order some 6 and 7 and give a try with it

[slowboy]

4 or 6 will work , blue springs, use really light oil in the dashpots