SU needles

[100SRV]

Just tried a set of BBC needles in the SU carbs on my 3.9 Rover V8 - I like the effect!

Seems to have better mid-range pull and not run out of steam at higher engine speeds.

The carbs usually have BDR needles (which I have refitted because:
1 the BBC's belong to a mate and
2 to convince myself that the change is real rather than imagined)

Can anyone suggest any other needle profiles worth checking?

cheers
100SRV

[leorest]

www.burlen.co.uk/
www.burlen.co.uk/faqDetail.aspx?faqID=8

A while ago I did Google some software which gave a database of all the needle profile types. Only ran on DOS though. Might be worth a try?

Edit to add 2nd link

Edited by leorest on Tuesday 12th September 14:05

[eliot]

get or borrow a wideband lamda sensor to actually measure your mixture.

[Pigeon]

http://pigeon.dyndns.org/stuff/x/sune

[JWB]

You really need to measure your exhaust gas to determine the mixture. So as has been said borrow a Lamda sensor or get to a rolling road with an operator that knows what he is doing.

Chances are he will file the needles to suit. You will not be disappointed with the results!

John

[love machine]

Find WinSU and download it.

[100SRV]

Many thanks for the responses, WinSU is great! I'll have to save up for a visit to a rolling road I guess...
100SRV

[love machine]

Also consider the operating parameters, if you're going for maximum power, you want to have a richer than normal mixture, so, if you leave the carb alone, it will over richen upon damper lifting. Have a think about that and sort it out. Clive Trickey's mini tuning book has a "How to bugger up an SU carb" perhaps better than Vizard. It's worth thinking about as your accellerator pump action could screw up your "Right needle for the job".

I wondered if the brake testing rig at your local garage could be used to get a constant load and allow you to fine tune your engine via rev rise/drops. Bit more tricky than with megasquirt though. I'd bin the SU's and megasquirt it

[100srv]

As a result of a blat along roads near Gaydon today I think it is powerful enough as it is - the next big thing to improve is the handling so I don't have to slow down as much for corners and to sort out the steering; I think that the front swivels could do with a rebuild and the steering damper may be past it's best.

thanks again!