B18 SU needle recommendations?

[HWKWallis]

Is anybody running a similar spec to the below and would/could recommend appropriate needles for twin SU.... Presently looking to KN but aware the likes of Brookhouse have various others listed.

B18 rebuilt +60
Raised compression no head or valve work
K cam
Recon carbs
123 distributor
B20 cold air box and feed (as photos)
2" system (assuming I can get it to fit)

Apologies for the stream of request recently but getting close to finishing after a few months of struggles!

Jim

[Ron Kwas]

Jim;

Here is good reference/baseline info in Metering Needles, from the factory: https://www.sw-em.com/su_carbs.htm#Metering_Needles

Please give source and info on the intake bells I see on those carbs.

Cheers

[HWKWallis]

The stub stacks come from MED engineering in the UK although they seem close in design to ones I had used previously on some Hd8 carbs feeding a Turner V8 which at the time I sourced from bccp fuel systems in Holland. Bccp had a fair amount of test info for their HD8 version when employed on the triple carbs of an E-type.

Jim

[red122]

I have fitted KI needles in my last amazon rally build . runs less rich and pick up is really good

[HWKWallis]

Thanks for the recommendation.
It seems to me that the KI is leaner by than the KN or KD by some degree on paper... But then idle is richer, so when set from that point I understand the whole curve effectively lifts proportionately?

Think for the minimal cost I'll weld in a lambda and look to someone with an AFR sensor to help set up!

Jim

[Derek UK]

At true idle the HS needles have the same measurement. Idle revs probably considered to be about 850rpm on average but a tuned engine tends to prefer something near maybe 1k to 1.2k so the needle measurement at these revs will be reduced to varying degrees. For engine specs that don't have established precedents for needle selection, the only real way is to get the car on a dyno at a shop that really knows SU's inside out. They should be able to either select needles from the range for best performance or perform black arts by grinding the needles at various positions. If the latter they should be able to measure the changes and match them with standard needles. Dyno time is expensive so finding a ball park needle type quickly is needed.

[HWKWallis]

Hoping the tune on this will live at the lower idle range. Am aiming for an easily repeatable needle so expect some compromises!

Jim

[northNH]

http://www.gunson.co.uk/tech-torque/Colortune-See-inside-the-combustion-chamber

Always thought it would be interesting to see how this compares with experienced trial-and-error...