The V8 Owners Forum -

I'm gradually getting the bits together to start my engine build but can't find much info about the carbs.
I'm going to use my p6 carbs (and distributor, 3.9 cam, standard valves and mildly ported heads) which I understand will run lean if left unchanged - does anyone have a suggestion for needles & springs?
I'm not expecting to get it right first time but don't want to drive it too lean on the way to a rolling road to get it done properly.

Just checked my SU refernce catalogue. The P6 3.5 with HS6's ran AUD1536K or the richer CUD1102 needles and AUC1167 springs. It shows no option for richer settings. Later P6's ran HIF6's which means you could go for the SD1 needle and spring HIF6 option of CUD1109 needles and AUD4398 springs.

It might be worth giving Burlen Fuels a call in Salisbury

http://sucarb.co.uk/carbspec/carburetto ... s/id/2255/

As note:

AUD1167 springs are Yellow code, 8oz @ 2.750" length

Ta for the info but the new engine is a 4.6 - I'll get in touch with Burlen and see what they say

My 4.6 has been running with SU carburettors since 2007, covering over 100,000 Miles since that time.

Is your engine fairly standard or upgraded in many different ways, as the needles and springs will be dependent upon either?

If the former, I would start with BAC needles, and if these prove to be too lean, try BCA. For springs, go with yellow graded 8 oz.

My engine runs BBW needles, but these have been polished.

Ron.

Cheers Ron, its pretty much standard - imagine a p6 engine but with a 4.6 block instead of the 3.5 one - so I'll try BAC needles.