Twin S.Us on a 3k

[Crashly]

Hi Guys,

I have a set of twin 1" 1/4 S.Us on my 3k, and am curious as to what size needles other people are using.

Any help would be greatly appreciated.

 

[altezzaclub]

Run through "The Girls KE70".  I fitted them to it and bought new needles then sanded the needles down to get a good mixture right through the rev range.

A leaner needle is made of thicker brass so you sand it back to make it richer where you need it.

There is lots on the web about needle selection (or there used to be) especially the Mintie active needle chart.

[Crashly]

Thanks, I'll have a read through the build diary

Seems the mintylamb site no longer works (well for me anyway)

[altezzaclub]

Nooo  ! !  You're right, the Mintylamb has gone!!  Dammit, it was so goodl!

Teglerizer will do similar, but nowhere near as nice to use.

http://www.teglerizer.com/cgi-bin/needle090db.cgi

OK- what needles are in there now?  I had AAP in mine, but i don't think they were used on a K motor before I bought them from a guy on here.  They were too lean & I bought a pair of ABH from Fabre, the agents in Sydney. They were too rich so I sanded down the AAPs in the areas needed.

Luckily I bought a display meter off someone on here too, so I ran two oxy sensors from the wrecker, one in an extractor branch of each carb. You could assume they are the same anyway, and just run one mixture meter in the exhaust somewhere.

Then its a matter of warming the motor up (the oxy sensors don't work until hot) and reading the mixture as you drive around doing daily stuff. I'll find the data on which 'station' on a needle refers to which rpm, and then where you have a lean flat spot you sand the needle 20 rotations at so&so station to make the needle thinner and the mixture richer. You'll need calipers to measure down to one thou

If it is rich over all areas, raise the jet to lean out all stations. If it is lean all over lower the jet. If it is rich in some areas you can't fix that without new needles.

I have a very lean idle, about 17:1, downhill is the same a lean cruise at 100kph of about the same, but it richens to 14:1 as soon as you go up the slightest incline, even if you don't touch the throttle. Boot it and it goes to 10:1.

You can do a lot with SU carbs, I've never finished experimenting with them, I just got distracted by a 4AGE in that car and the 4K with SUs went into my gold car.

 

Edited October 17, 2017 by altezzaclub