6 replies to this topic

[finch661]

dont know if this is the rigth section, but it does relate to needle selection. i have bought the winSU software and have inputted all the cars details, and it has outputted some needles to try. my question is how is the best choice needle determined, and when you compare different needles how do you know which is best from the graphs?

thanks

[Ethel]

http://www.mintylamb.co.uk/suneedle/

You can put them all in there. If you're planning a rolling road session, a leaner needle can be filed richer but you can't do it the other way round.

[finch661]

ah thats a nice website. but then how do you make the correct needle selection?

[Ethel]

No pc software can know the peculiarities of every engine. WinSu will make a good guess. You can either try them all (expensive), opt for a middling one or get the leanest and take a file to it if needed - or let a rolling road operator do it for you.

[finch661]

hmm maybe a rolling road session is best then (as soon as i have money ) regarding the comparison graphs that that website outputs, what do the curves mean/what does it tell us?

[Ethel]

A richer needle will be higher up the graph. The needle is divided into "stations" along its length that's what's plotted on the x axis, as if the needle was lying along the bottom with the clamped end on the left.

The more air going through the carb the more the needle is drawn out of the jet and, because the needle tapers, more fuel is able to flow.

Idling is on the left and wide open throttle is on the right.

[finch661]

perfect, cheers for your help