SU carb conversion and Air filter box?
 

Hello everyone. It's been a while, hope you're all ok.

I've finally done a very exciting thing I've been meaning to do for years: I've changed the single Stromberg carb for single SU HIF44, off a Mini 1275. It's an absolute transformation, I'm so happy! I've always been an SU man so I'm biased, but it's really remarkable the difference. I wish I'd done this 10 years ago...

However, my choice of air filter was limited and I ended up with a Fletcher cone filter. It looks a bit boy-racery, and it makes a silly hissing sound which masks the lovely new throaty sound from the engine. I'm wondering if it would help if I got a box made to house it, with a hose inlet to reach for cool air from the front. Has anyone done anything similar that I could copy?

Thanks,

Andy.

Have you kept the same needle that was fitted for the mini, or changed to the 'correct' one for B18/20?

How about a cold air intake setup from a 140 series car? Would need a bit of modifying or you could just modify your old Stromberg air filter I assume also.

Interesting about the HIF44 being a good improvement.

As said, using the standard Stromberg box, adapted as need is best. Cheap, simple and works, what more can you ask for. Post a pic of your engine with the original carb/filter set-up.

Thanks folks. Burlen lists a needle for HIF44 for Volvo b18 conversion, which made needle choice a lot easier!

Modifying the old box: yes, it seems like a good bet in principle, though the bolt hole arrangement is different. The other issue is that the SU actually has a wider throat - although 1.75" is nominally 44.5mm, and the SU is a 44, the throat is actually about 48mm. I could grind the hole out in the Stromberg box, but the inlet pipe end is narrower still, and it seems daft to restrict total airflow by cross-sectional area before it's even got to the outside of the filter. So I'd need to change the inlet pipe too. You can see from the attached photo that it's one of the sealed unit types, but I guess as it's useless storing it in the garage I might as well rip it open and see what I can do with it.

I would look for a 140 73 onward type air box that uses the same filer as the twin carb setup. That will be a lot less trouble to modify.

If the photo is your car I would strongly suggest changing the steering coupling back to the correct rubber one. Poly is not a suitable material and when it fails it will do so without warning and rip in two. I am amazed anyone one is still selling them in all honesty

I think it came from Brookhouse!?

Interesting! Did the old linkage connect up ok?

OK would be an overstatement. Had to cannibalise the choke linkage off the Stromberg because the SU has a MASSIVE spring on it. And the kickdown linkage for the auto was a pain and I had to call on the services of a friendly welder. But it's fine now!

The smaller size of the inlet nozzle is largely irrelevant except at continuous full throttle. i.e. with the butterfly fully open. The taper also helps to quieten and control the flow. Check back to Mitch's thread where he opens up his filter. Once you have the back plate you can make an adaptor from thin sheet and have it spot welded on. (Solder, pop rivets and sealer as alternatives) Bolt the plate to the HIF. Weld nuts to match the 3 existing bolts to the new adaptor to hold the outer part of the filter to the inner. Shorten the bolts to suit. Make sure that your adaptor plate doesn't cover up any of the vacuum holes on the face of the HIF.
Pictures please. 😊