SU Carbs

[Richie]

that might be part of a rebuild kit, I guess im just going to get one a hope for the best. Thx for advice

[Richie]

Ok I'll bare that in mind, thanks

Regarding this pic


Mine is slightly different in that the blanked off bit next to the fuel inlet in the pic, has another pipe coming out on mine. Ive connected it to the fuel return hose on mine as if I pump fuel (engine off) into the carb it comes out of here eventually.

But now that its connected if I continue to pump fuel in, it will come out of the overflow pipe at the top. Shall I just blank the lower one off and run the overflow as normal with a hose to the fuel return? Or just exiting under the vehicle further back?

My carb is identical to this one (with the vac advance exactly where this one is)
Ive been reading this on page 6 and the way I understand it is that if your vac advance is in the same place as this one (on the inlet side) then you must block it off as it will make the car run bad?

Mine vac advance has a hose coming off it and going into the dizzy...

Have I understood this right, should it be blocked off?
Thx

[twiss]

It depends on the carb... the vacuum advance on an SJ should be sucking at high throttle.
Problem is most Minis (i think) are the other way round and suck at idle...

On an SJ you get too much advance at idle and not enough at revs.... just take the pipe off and hold it against your skin at different revs, you should be able to feel if its sucking or not

[djc]

Handy thread this. I now have 2 SU HiF44s and have a few questions please. Both mine have BER needle fitted which according to Minty is significantly leaner higher up. But one of mine came of a 413 and the guy said it ran well. The other is a new rebuild for a Metro 1300 and also has a BER in it. Is this worth a go or do I need to get a BDL? Given all the other variables and potential probs, I suspect start with a BDL so if I have issues I can at least eliminate that? And do I need a jet, the ones in there are both the 100 thou and should be fine.
On Burlen there seems to be a BDL with or without spring? Mine both have a spring under/behind needle so I guess I need a spring one (they dont show decent pics).
I've read here about issues regarding vac advance when using these SUs - do I start out assuming I'll have problems or is there a fix at the install stage?
Sorry for all the questions, but keen to avoid hours of frustration making this switch.
By the way, cheapo SU 44s... search Metro spares cos Metros are crap so no-one fixes them so the bits can be cheap

[twiss]

WinSU is a brilliant little program for looking up needle profiles. You can access them in the free version, but lots of other features are disabled.

http://www.winsu.co.uk

You will also need to install the .net framework which can be found here:
http://www.microsoft.com/en-us/download ... aspx?id=26

You should be find with the 100 thou jet, most needles for HIF44 are for 100 thou anyway...
and Yes the needle should have the spring on the bottom, but you can swap them between needles.

Vacuum advance is pretty easy to work out really.
When you get the engine fired up on the SU, put your finger over the vacuum advance hose.
If it sucks at idle, and less at revs, it is wrong and will need blocking and a new vac advance drilling on the other side of the throttle disc
If there is no suction at idle, and more suction as the revs increase, then it is correct!

[twiss]

Here is a graph of various needle profiles...

red - bdl - 1.3
green - bcz - 1.3 (this is the needle rhino ray recommends, i tried one and found it just as good as the BDL)
blue - BER (yours, as you can see, quite a bit leaner at WOT)
pink - BFM - 1.6 suitable for vitara engine

[djc]

very handy Twiss the SU man I'm going to get a BDL, sorted. I understand the vac issue from your notes.
I need to figure termination of throttle and choke cables (nothing there on mine) but once I have the manifold in my mits I may figure out what and where - if anyone has any pics of cable mounting/termination I'd be grateful. My SU is either of these (I think the choke mount varies).
20 minutes indeed
here's my SU re cabling:

sj5.jpg (33.54 KiB) Viewed 9333 times

p.s. on the left one there's a spring-loaded plunger thing, up and right of choke lever. Is that a tickler?? I used to mess with v old bikes and they always had a carb tickler to squirt a bit of fuel into the chamber.

[twiss]

Easiest way of mounting the cables is to use an "abutment bracket" from a mini

http://www.minispares.com/product/Classic/CAM4942.aspx

[djc]

Re Vac advance, I also looked through Anton's build as there was a fair bit there. Both the 44s I have have this:

su1.jpg (12.35 KiB) Viewed 9323 times

That's viewed with inlet flange to right, throttle cam in background right. I think this is the vac advance? and it goes in to the manifold side of the butterfly thing. If I follow the Anton thread re vac advance it should enter other side of the plate/butterfly/ flat thing that opens? Here's the hole:

su2.jpg (18.57 KiB) Viewed 9323 times

1] Is that right please? and 2] I can't see how it makes any difference except at tickover plate closed.

Shall I just drill a hole, stick some pipe in and believe??

Reading Anton's, the chances of me fitting and running this and meeting emissions etc all in one single day appear slim, I fear.

[dan_2k_uk]

you need to re drill that hole on the opposite side of the butterfly and blank that one.

I had a bit of brass pip off my old carb I was binning that I was able to make a push fit in the hole I drilled.