Hi All,

I thought this might be a handy reference if you are looking to buy a HIF44 for your (non-turbo) mini. As the HIF carb was fitted to many different cars in the 80's and 90's there will be some that are more suitable to minis than others

First up - make sure it's a HIF44. If you see a HIF38 the most obvious difference is the diameter of the throat is smaller (38mm instead of 44mm) but the easiest visual check is the face that meets the air filter. The HIF44 is a bit more square on the sides and top edge
https://www.theminiforum.co.uk/forums/t ... cs-please/


The other similar carb is the HIF6, which was an earlier version of the HIF44. It can be identified by the HS-type dashpot, spring and damper rod on top. The HIF44 carb uses a different dashpot and piston with a ball bearing, spring and damper rod


The ball bearing race means the dashpot has lower friction, and can react quicker to throttle inputs. It's worth checking all the ball bearings are in place and haven't escaped - the plastic race is normally captive on the dashpot lid, so if it comes out there might be an issue.


The bigger diameter HIF44 type spring


Next up to check externally is what side the throttle and choke mechanism is on, and the type of arms you have. The mini throttle arm has a cam type, which gives more sensitive input at the start of the pedal stroke, then opens quicker the further you press the pedal. The usual mini setup has the accelerator and choke cables on the LH side of the car. You can definitely use carbs with different configurations, but if you can find a mini type carb it will be a bit easier to start with. There should be a concentric return spring on either side of the throttle shaft too

I'd also avoid any HIF carb with an auto choke mechanism


The special throttle cable locates in the abutment plate, and then curves around the cam to the bottom. The outer choke cable is clipped to the abutment plate and then bolted to the choke arm (not shown in the photo below)


On the other side of the carb will be the various ports:
Fuel inlet - yellow
Fuel bowl overflow/vent - red
Crankcase breather - blue
Vacuum advance - green
Idle mix screw - purple arrow


If you want to fit it to a mini for performance use there are a couple more things that are desirable to have, and which are handy to have in advance. Plain throttle blade with no poppet valve


Vacuum advance port pre throttle blade (on the air filter side of the throttle blade)


The spacer and abutment plate to suit a mini


Initial setup video https://youtu.be/prX1NXUfljM?si=dA0hQuJoAJaTBpHa

Helpful part numbers:
Throttle lever JZX 1605
Choke lever JZX 1609
Throttle cable SBB10099
Abutment plate CAM4942
Choke cable clip CZK6491
Throttle and choke trunnion AUE34

Springs: available in red, yellow, blue
Needles: all HIF44 carbs use the larger 0.100" diameter needles, so you must use a needle that starts with "B" - eg BCE

_________________

As an owner of both types, the 44 is judged to be too big for a small bore engine, whereas it is just right for a 1275. I was able to determine that my 38 came off the same size engine as I was wanting to use it on.
BTW the HIF 6 is the imperial sized 1-3/4" carby. The HIF44 is, well, 44mm, from the later metric products and is slightly smaller.

Great post, thanks

_________________
The bitterness of poor quality (or Crappy Workmanship) remains LONG AFTER the Sweet Taste of Low Price is forgotten.

Hi Timmy, great post - thankyou.

Great post Timmy!

What spacer is used for an Aussie round nose (in my case a Mini K)? Cole from Classic Mini DIY mentioned a thin spacer and adjustable engine steady are required for a HIF44 to fit a Mk1

I can't be sure on every manifold and combination available, but on my 1100 engine with the factory engine steady it all fits OK. I've got a Metro type manifold, original spacer, offset KN air filter. I also have a 90 degree speedo adapter left over from the Dellorto carb, so this may help too (I haven't tried fitting the carb with a standard speedo cable).

A 1275 engine block is about 1/4" taller than a small bore block, so I think this should add a little extra room? If you have the original remote shift on your K there might not be much you can tilt the engine forward before the remote housing hits the tunnel

_________________

Thanks Timmy - appreciate your help and I think you're right, the manifold could make a difference in available space.

Yes I've got a remote gear box and I was thinking trying to tilt the engine would only have marginal gains if any.

Thanks for the info and tips for buying and setting up these carbs. I am in the process of converting from twin 1 1/4 SU's to a single 1 3/4 SU, I am going to daily drive the car and want to simplify my set up and duct the intake to the front of the car to quiten it up.

Can you please steer me in the right dirrection, from what I have researched thus far, the carb needs a 0.100" main jet? And I am not sure what needle is a good starting point?

Engine build is,

1100 40thou over
12G202 head ported with large race valves
Road/mild race cam
LCB extractors
1.3 roller rockers
balanced
Aldon yellow mech dizzy

I have cleaned the carb up, put it on the car as a test run, all running well, bit big dead spot after about 2000 rpm. Current needle in the carb is a V3 which I'm not even sure is the right needle for this carb? I pull the choke out in the dead spot to help fuel it, it help a little. The carb is setup correctly for idle and lower RPM with idle and plugs colour correct.

_________________
1968 Morris Mini Deluxe - members gallery
1970 Morris Cooper S - members gallery
Mini's I grew up with
Slot car couch

I have started tuning my HIF44 and so far I’m using:
BCE needle
Yellow spring
HPR30 dashpot oil
It’s running about 90% decent, a few rich and lean spots but I’m not sure if I can get much closer without a custom needle
My engine is a similar spec 1100 to yours (bored 080, worked head, RE266 cam, etc)

There’s a few notes from the initial tuning here:
viewtopic.php?p=1072905#p1072905

Edit: sorry I misread your post- you’ve got an HS6 and not a HIF44. OA6 is a good starting point for a needle
The HS6 should have the 100 jet and most would have a fixed needle, but you could convert to a swinging needle with a different dashpot

_________________

Thanks for that,

I ordered a AC needle and red spring as a most basic starting point. Still huge flat spot once past 1/4 throttle which I am convinced is running too rich but idle setting is set properly. I am now thinking I have too much fuel pressure for the bowl, I was running twin 1 1/4 carbs, I think now going to 1 needle and seat it is too much pressure. I have ordered a inline pressure regulator with settings of 1 - 6 psi, I am somewhat confident this could be the issue. I will let you know how I get on.

_________________
1968 Morris Mini Deluxe - members gallery
1970 Morris Cooper S - members gallery
Mini's I grew up with
Slot car couch

An AC needle is a 0.090" needle (as is V3), so if you have tuned the idle to suit a 0.100" jet it might have a strange fuel curve.

Once it starts, let it warm up to temp. It should need the choke to get going and stay idling till warm. You should be able to hold any rpm in neutral without missing or fouling, and you should be able to whip the throttle open quickly without it stumbling or having dead spots.

_________________

Thanks Timmy,
Seems classic mini diy website not to good advice, I will do as you suggest and try get my hands on a OA6 needle and go from there, will fit the regulator also for good measure as I am fairly certain the current pump would be delivering around 5 or more psi.

_________________
1968 Morris Mini Deluxe - members gallery
1970 Morris Cooper S - members gallery
Mini's I grew up with
Slot car couch

I’ll get him to update that. The 1275GT would have had a single HS4. I don’t believe any mini came with a single HS6 from the factory

I think he used the list from here
https://www.7ent.com/pages/articles-tec ... eedle.html

_________________

Ok, interesting developments today. I got a second hand TW 100" needle from my local old school mechanic. Went to try it along with the new regulator, didn't fit, since discovered the guy I bought the carby from rebuilt it with a 090" jet as well as V3 needle. So I drilled out the jet to 2.52ish, very close to 100" as I could get it. With the TW needle, slight improvement.

Instead of ordereing a heap of needles I decided to lend my hand at profiling this TW needle to see if I could get closer to required result. I profiled it to OA6 and this was a vast improvement, still struggling at top end full load. I then profiled it to a KW which was similar to the OA6 at the lower stages but richer up top. This was a huge improvement, with the regulator at 2psi I seem to be getting pretty good results. It is still slightly to lean at the very top end, but it has also been very cold today, so with warmer weather it will be interesting to see how it goes.

Never thought I would be profiling needles but a cheaper and quicker way to experiment.







I think the next step is a AFR gauge and see whats happening before any new needles now.

_________________
1968 Morris Mini Deluxe - members gallery
1970 Morris Cooper S - members gallery
Mini's I grew up with
Slot car couch

Bit of an update here, after a lot of fie tuning I have the carb dialed in better than ever before, probably about 90-95%, would need a dyno to get it any better I think. The turning point was getting the AFR guage in, with out that it really is such a guessing game, the AFR guage was very good bang for buck when it comes to tuning the carb. I anded up scrapping the air duct I built, it was restricting top end too much and would have lead to a weird needle profile. I fitted a 1.5" ram pipe with air piper cross air sock, a OA7 needle and the HS6 SU is running like never before, the engine has awesome mid and to top end power and wants to rev and breath now. A HS4 would be better for low power but I am very happy with how it has ended up, it is now how thw engine should hav e been performing for a long time. Mainly due to having the AFR guage in the car.

_________________
1968 Morris Mini Deluxe - members gallery
1970 Morris Cooper S - members gallery
Mini's I grew up with
Slot car couch