I am wanting to buy a set of new HS4's for my 69 Mk2 S. If I buy a set for an MGB i.e. AUD 135 or AUD 325, do I need to change the fuel bowl rubber buffer to get the 30 degree angle rather than 20 degrees for MGB?

Is it possible to replace the fuel bowl lid with a standard mini type to get rid of the overflow type of the MGB?

I know it would be cheaper to replace with a set of FZX3050's, but I do not like the inlet setup and overflow pipes.

Thanks Fritzie

Yes, you should change the float bowl adapters to 30 degree ones so as to keep the bowl vertical. This was done on the NSW Police specification HS4's.

Don't have the knowledge to answer the float bowl lid change question.

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ex-NSW Police 1970 MK II Cooper S
VMCI #43

Just spent an hour checking carbs and numbers to help here and find I've logged out and it lost it all....

Short version:
lids for HS2 and HS4 twin setups can use the same fuel bowl lids, so long as they are only used on the RH (clutch) or LH side, due to the screw hole pattern.
I have HS2 twins and HS4 (SPO41) twins and they run the same lids:
RH AUD9203
LH AUD2277 (cast into lid) or AUD9258 (etched)

I also have a set of FZX3050 and didn't realise they're for MGB. I need to change lids too but didn't think about 30 degree angle.
Thanks for the warning.

Thanks to both Doug and Bill.

Just to put your mind at rest Bill, the FZX3050 are specifically made for Minis. On the SU Midel site, they are listed as a conversion kit for Mini Coopers. A few of the UK Mini sites indicate these as replacement carbs for the older HS4's. So I assume the fuel bowls are set at 30 degrees. I think I read somewhere the FZX3050 kit are AUD640 carbs, although it looks like fuel bowl tags are FZX3050.

Regards Fritzie

I ended up buying a set of FZX3050 and they arrived this morning. I thought the supplier would have asked what needles I required, but this was not the case. I was not concerned as I had a pair of No 6 and CP4's.
Pulled the needles out expecting a set of fixed needles, but found they are the floating type. They are AAK.

Attached is the chart showing station diameters of the above needles. Has anyone any experience with Floating needles and how do you think the AAK will perform in relation to No 6 and CP4's.

My FZX3050 pair of HS4s also came with swing needle set-up.
I preferred the fixed needle setup and bought these conversion items to use fixed needles instead. Easy to fit to the carb pistons.

https://www.sumidel.com/shop/item/needl ... -and-screw

I use floating needles in my HS6's - no problems with them.
Floating needles were also standard fitment on the later Mini's with HS4's and the likes of the Morris Marina.
The down side of the floating needle is that they wear the jet over time - but I would suspect it would be a long time on a car that does minimal milage.

Unfortunately doing a comparison of fixed v swing profiles is not possible due to the different length of the needle and thus the mixtures. It quickly becomes a tedious game of trial and error. You may well be better off getting the conversion collars for your fixed needles.
As it turns out the AAK profile may be close to what is needed anyway

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Cheers Dave.

Thanks for the responses. Verifies my thoughts. I found the conversion collars last night and ordered a pair from SU Midel. In the meantime, I will install the new carbies and see how it performs with the AAK needles.

For your interest and possible disgust, I bought the set of FZX3050 to replace a set of 38mm Hitachi SU's that came with the car, when I purchased it in 1989. I have a mostly original 69 S and wanted proper SU's to at least make the car somewhat more original. For your interest and amusement, I have attached a couple of photos of the Hitachi SU's. They are very similiar to normal SU's and have been performing very well. They have 92 thou jets rather than 90 thou of normal HS4's. Currently running CP4 needles. It gets up and boggies really well. More than enough for a 68 year old, who thinks he is still 18.

Life's more fun when you live the age you think you are. Just forget about the number of candles on your last birthday cake.

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ex-NSW Police 1970 MK II Cooper S
VMCI #43

The Hitachis are interesting. I knew they were on Datsun 240Z, but have never seen them on minis before.
You have some interesting carb setups to play with now!

If only they had an accelerator pump...

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did I tell you that I won a trophy?

SUs do have an accelerator pump... its vacuum powered. Which is why its important to have the right oil in the dash pot. That's what controls the degree of richening when you open the throttle.

As far as the choice between fixed and swinging needles is concerned... there is no choice. All the needles belong in one set. At some stage BMC et al decided to change to swinging needles so if a particular needle is what your car wants then it will be available in fixed or swinging type. You will not find a fixed needle with the same specs as a swinging one. Which is no big deal because they made a little adaptor so either will fit any particular carb.

As for lengths ?? I think that's one of life's mysteries. Fixed 90 thou needles are about 1 1/2" long where as floppy ones are about 1 3/4". However, at the top of its travel the piston protrudes slightly into the bore and at the bottom is the bridge. So, an HS4 carb needle has a travel of about an inch and a quarter.. As the measurement stations are 1/8th inch apart it means that, at full throttle, station 10 is at the mouth of the jet.

Maybe it has something to do with smoothing the fuel flow at the jet outlet. But if anyone has a good theory as to why fixed needles have 13 stations and floppy ones 16 I'm all ears...

With regard to "......and how do you think the AAK will perform in relation to No 6 and CP4's.".... I'd suggest its a case of suck it and see... The AAK is leaner across the board compared to the other two. Your engine may prefer this .... or not.

Many years ago my Mini spent quite a bit of time on a dyno with a very knowledgeable (in the ways of SUs and Minis) person. After spending a LOT of money on needles (no one would take back the ones that had been tried and rejected) we found a set that maxed the power. The final set produced as much power but with less fuel flow..... Bingo.

Good luck.

Cheers, Ian

I think that I may need to put back the Hitachi SU's. What do they say - "If it ain't broke, then don't fix it"

Fitted new HS4's yesterday. No way I could get the mini to even fire. Maybe 1 slight cough when my wife was cranking it over, while I was checking for spark.

Ended up taking out the new CSI distributor and put the old 29D back. At least I got a cough, but still would not start. Checked float levels - all OK. It has got me stuffed. If I leave it for an hour, I can get a slight cough from it. Nothing else. The spark plugs are certainly not wet after a far amount of cranking, so maybe I need to look further afield and see if anything is amiss with the new carbs.

Checked my new CSI distributor as per manufacturers check video and it seems to be working OK. Currently set on Curve 10.

Might have to wait until I get the conversion kits for the fixed needles and replace this swinging type. They are certainly leaner than CP4's that I had in the Hitachi's. I would have thought that it may have at least fired up and then stopped. The AAK needles are reasonably similar for the first two stations, but are considerably leaner after that.

Any suggestions what I should check or try would be appreciated.

Regards Fritzie

Have you checked that the little fuel delivery lines from the float bowl to the jet are actually delivering fuel? They are fairly easily kinked when inserting the jet into the carb. Strange it should happen on both though....

Did you do a piston drop test to check the needles are moving freely? If the carbs are still attached to the engine stick a finger down the carb and see if the piston slides up and down freely... If not then maybe remove the damper and try again.

All needles are pretty much the same at idle so the car should at least start and idle (maybe not that well) even if you have the wrong needles (if the carb is actually working properly).

Tip a teaspoon of fuel directly down each carb throat and try to start. If it fires then you know you have a fuel problem rather than an electrical issue... Or try a squirt of “Start yer Bastard” if you have some..

Just fishing.......

Cheers, Ian