Carb needle advice

[Ministrone]

Can anyone recommend me a carb needle?
I have a standard 850 bottom end with a skimmed 12g295 head, single 11/2 hs4 carb, pipercross air filter, mini spares Inlet manifold, rc40 exhaust.
It's currently fitted with an ABA needle as this is the nearest equivalent I could find to the old E3 recommended by Mr Vizard but I'm not sure this is right. I also have a AAA needle which is quite a bit richer.

[ianh1968]

Get this spreadsheet here:
http://mk1-performance-conversions.co.u ... l_carb.htm

The spreadsheet has automatically chosen some swing-type needles
which are very similar to fixed type E3.

Needles.ods.png

You can click it a couple of times to make it bigger,
Click the "Back" button on the browser to return to the post.

Ian

[Ministrone]

Thanks for that Ian.
It looks like I'm quite close with the ABA needle.

[carbon]

As well as needle, the dashpot spring also affects the mixture significantly. Which spring are you using?

And 'vizardising' a HS4 carb bore weakens off the mixture at high rpm high load conditions. Enough to burn out exhaust valves if you don't alter the needle...