SU conversion

[Malcolm Parker]

My 31 SWB saloon has run for 18 years with a side-draught SU on a standard cast iron manifold (with the inlet restriction bored out) and I use the standard scuttle tank with no pump.  I have never had any problems with fuel starvation but always carry a spare gallon just in case!  I have never used an in-line filter. It is a  simple job to remove the fuel tank and get all the muck out.  I check the fine gauze filter in the banjo union on the carb about once a month.  The AN or EB needles seem pretty good.
I have recently fitted one of the Ricardo aluminium cylinder heads and the results are very encouraging.

[Paul N-M]

Robin, Derek,

I endorse the suggestion of starting with a new jet.

For comparing needle profiles take a look at the excellent http://www.mintylamb.co.uk    If you want to get very exacting but don't have access to a rolling road (my nearest is miles away!) set up a camera pointing into the carb inlet to record what stage (height) your needle is sitting at for various revs. By using roadside adjustments to the mixture, this allows you to calculate quite accurately how rich or weak the needle is at each stage and choose a more appropriate one.

Peter.

Hi Peter,
Is the MintyLamb site up and running again?
I couldn't make it work the other day.

Paul N-M

[Colin Wilks]

The MintyLamb link defaults to /suneedle. If you look at the main page it shows:

"Since 2004 this site had been serving up SU needle graphs. In October of 2017 the host it used closed its doors. The pain of porting 12 year old code to another host wasn't something I had the energy for.

However, it turns out that the graphs were quite popular— far more popular than I gave them credit for. So, due to popular demand, I've decided that I had better keep this place going.

Please bear with me whilst I port the code across to something a bit more modern."