Which Carb Needle for 3.5L V8 with upgrades?

Hello,

Those of you who have read my previous threads will know I have had some issues with my engine recently, however things seem to be getting better now, and my next task is to try and rebuild my carbs.

While doing this, I have a theory that to get the engine performing / running better, I may need to change the 'needles' inside the carbs. Would anyone know which is the best needle to go for with the following setup;

Original Land Rover 3.5L V8, SU carbs with cone air filters, 'sports' stainless exhaust, and (although not done yet) I am probably going to look at fitting a H180 Kent cam or something similar (Viper Hurricane?) that people can suggest.

I believe the standard needles are 'BGC', although I have not actually looked to see if that is what mine has, I expect so.

Other needles that I have found people recommend on various threads include the 'BAK', the 'BAF' and the 'BBW'. Each of these apparently add more fuel at higher engine speeds, with the BAK being the smallest increase, and BBW being the greatest.

Given that when idling, the mixture is too rich when I set the carb mixture to what seems right for driving, I assume my current needles need to be changed to one of the above to allow for the mixture to be better controlled by the needle rather than just setting mixture rich for idle. (For reference, the reverse is also true, if I set the mixture right for idle, it seems too lean for driving, i.e. less power, occasional misfire at high revs ~4500+ rpm)

Any guidance on these needles would be appreciated, thanks.

Standard needles are or should be ok for what you have done so far with filter & exhaust replacement as they have only a small part if any in increasing power.

It's when u start fitting fast road high lift cams that the right mixture has a part to play, and that is trial and error with needles and or jets and a run on a rolling road if you want to get and know what the max power from your engine is.

Sounds as u have mechanical probs not tuning ones

I used a program called WINSU, combined with the online mintylamb SU needle calculator to some success. I've got HS carbs on my V8 and it's a high comp one with SD1 heads, free flow filters, less exhaust and a +20 overbore, standard cam. KO needles are a bit rich top end (but are still in to reduce the chance of high speed pinking) so I'd go for KK if I had a lower compression ratio. There will be a 3 letter HIF needle that's equivalent, it may well be the middle one from your three. They're not a lot of money so experimenting is relatively cheap. If it feels too weak it probably is, and adjusting the idle richness will only work to a limited extent by making it richer the whole way through.

If it were me I would start by taking a bit off the needles you have with very fine wet and dry or metal polish.

Where to take it off/slim them down??

General rule of thumb is Bottom third of needle for hard acceleration, Middle third for cruising and Top third for idle

I personally used to file a flat on the back of the needle till I got it right, take a little at a time in the area you want to give more fuel, get the idle right first then go from there.

You could buy economy needles (thick ones) as a start and work them to suit your motor, you will be surprised at the results you can achieve with trial and error testing on the road.
Stop watch test on a given piece of road, or acceleration times from given points, easy

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Ok, thanks for the replies everyone. I will probably just buy the 3 of them then and try which seems to work best.