13 replies to this topic

[BaronVonchesto]

So my engine is back in the car at last and I fired it up for the first time! Sounds great! Can't wait to break in the engine and take it for a spin!

 

That got me thinking. What needle should I use for my car? Should I just stick with the Stage 1 AAU, or would a different needle be better?

 

this is a 998 with +40 pistons, CR 9.0, C-AHT88 head, EVO01 cam and Stage 1 kit fitted.

 

What do you guys reckon will be the right needle for this setup?

[ACDodd]

Stay with a lean needle and make sure the idle mix is set lean too for running in then get a custom machined one made to suit your engines needs once you have run it in.

Ac

[cal844]

Id run it with the AAU to see how it is on the road, if it needs to go richer try another needle or get it trailered to AC Dodd for a rolling road tune

[unburntfuelinthemorning]

Id run it with the AAU to see how it is on the road, if it needs to go richer try another needle or get it trailered to AC Dodd for a rolling road tune

That'd be a long trailer ride!

[cal844]

Id run it with the AAU to see how it is on the road, if it needs to go richer try another needle or get it trailered to AC Dodd for a rolling road tune

That'd be a long trailer ride!

Well worth the drive home though ?

[BaronVonchesto]

 

Id run it with the AAU to see how it is on the road, if it needs to go richer try another needle or get it trailered to AC Dodd for a rolling road tune

That'd be a long trailer ride!

 

 

about 12k miles!

[unburntfuelinthemorning]

Do you have any rolling roads where you are?

[Rorf]

That should run it in

[BaronVonchesto]

Do you have any rolling roads where you are?

 

i do yes... so get a printout of the power curve?

[cal844]

Do you have any rolling roads where you are?

i do yes... so get a printout of the power curve?

Ideally yes, you'd also want a selection of needles to try, you might find you'll be in between needles so a lean one will need filed. Ideally you want to get as close to optimal with an off the shelf needle.


There were charts available online to get a close spec

[unburntfuelinthemorning]

 

Do you have any rolling roads where you are?

 

i do yes... so get a printout of the power curve?

 

See what the air fuel ratio is at full throttle throughout the rev range.  Make sure it's not excessively lean or rich and substitute different needles as necessary. 

 

An SU needle chart is handy as it lists all the available needles.  Trouble is you'd need to invest in quite a number of needles to take with you to try unless the rolling road has a stock of them.  Someone who is used to tuning SU carbs would get the needle right in one or two goes just because of experience.  It is possible to file the needles to adjust them as Cal says but it's a lot of trial and error again unless experienced.

 

Keep persisting on here for needle suggestions as it will help you narrow your choice to say three or four which you could take with you and try on the rollers.

[BaronVonchesto]

yea i wouldn't mind 2 or 3 suggestions, but otherwise I'll just stick with my AAU needle. Not looking for every last BHP i can squeeze out of the engine yet. Certainly not worth the effort of multiple trips to a rolling road and buying many needles

[whistler]

 

Do you have any rolling roads where you are?

 

i do yes... so get a printout of the power curve?

 

No, find a RR that'll tune the needle as well as do a power run.

[ACDodd]

The problem is rolling roads that can actually do this are few and far between nowadays, and in other countries sometime non existent!

On my pop up tunings days I am seeing more and more poor workmanship from rolling roads who simply have either no clue, or should no better.

It is likely best if you can install a wide band sensors and then make your own needle.

Ac