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MG Midget and Sprite Technical - HIF44 wrong needle?

I am currently running an HIF44 carb on my 1133cc Sprite. It has an ADL needle, which is supposed to be the ideal for a 1275 engine. I am not getting good economy and the exhaust smells rich to the extent that a friend driving behind me said he could smell unburnt fuel and see a puff of black smoke on accelaration.
Have I got a too rich needle as I am about 150cc down on a 1275?
The car drives and idles smoothly.

b higginson

too many variables; have it set up on a rolling road.
David Smith

When I was at Peter Burgess' RR he said that the fuel to air ratio was very good according to the read out, which is one of the things I don't understand. Nothing has been changed since.
b higginson

The most common needle for a 1275 (or 1330 in my case) is BDL not ADL. BDL is the MG Metro set up. I tried all sorts of needles but ended up back with BDL after a rolling road session. I second David's comment - get a RR session.
Chris H (1970 Midget 1275)

Sorry. Brain fade. It is a BDL.
b higginson

Hi Bernie,

Clean air filter?
Choke control returning in fully?

You could try turning the jet setting up a little. But given you have already been on a RR with this make sure you mark, or count and record by how far you turn the setting screw so you can set it back where it was if you need to.
Guy W

Hi Guy.
Air filter is quite new (K&N pancake)
Choke fully returns.
Strangely, I had a K&N copy cone type filter but decided to get the real thing and bought the genuine pancake type. Didn't improve things though.
When I was at Peter's we were experimenting with different thicknesses of insulator blocks to lengthen and shorten the inlet tract. It didn't seem to make any difference what Peter did, even removing the stub stack showed no loss on the print out, so he bolted it back together as normal, advanced the ignition slightly and it topped out at about 50BHP at the wheels. Not bad for the engine size. It's just the poor economy and the apparent richness that is bothering me.
The carb came with a BGF needle in it but I never ran it with that needle in as the general opinion was that the BDL was better. I've just been looking on the net at some charts and the BGF appears to be a leaner needle than the BDL, so I think I will try that as it may be more suited to my smaller capacity engine.

b higginson

hmmm, thin ice Bernie; the absolute last thing I'd do is monkey around with how PB set it up. I'd call him for a chat though...
David Smith

once again I'm with David and Guy (on checking only not adjusting)

so many variables, so many interaction parts or components any one of which could be worn, broken, blocked, snagged up, etc.

you put >>When I was at Peter Burgess' RR he said that the fuel to air ratio was very good according to the read out,<< so why change the needle

>>Nothing has been changed since.<< something must have or it would be as read out
Nigel Atkins

OK, thanks chaps, I guess I'll have to re-think things. It's only the needle I'll be changing and I can soon change it back again.

b higginson

another typo on my part I meant something has changed rather than you've changed anything

changing the needle will negate your previous RR tune up somewhat as adjustments with probably have to be made and they're different profile needles (I haven't the first clue how much different mind)
Nigel Atkins


You must always ensure that the bypass airway for the carb - I think that is what it is - but anyways the hole or maybe holes at the inlet face of the HIF 44 carb, see pic - are NOT covered or obscured by the filer gasket - or anything else. If they are, you will get the symptoms so described.

Yor rolling road needle set up may well have been OK - as they usually do this with filter off. If you then replace the filter and cover up the holes in so doing with the gasket, then you will experience the issues described.

Simple test - remove the filter and gasket and drive the car....If it improves, you know why.

Photo isn't the best, but I seem to recall the hole is the bottom one of the group of the three holes on the top right of the inlet face of the carb.
Mark O

...apols pic attached

Mark O

Thanks Mark. Something else for me to check. It will probably be wednesday when I get to it. Either way, I'll post the results on here.

b higginson

Doesn't the HIF have a common failure point in the choke mechanism that causes it to dump a lot of raw fuel into the carb throat?

C R Huff

Not heard that Charley. Anyone else know about that?
b higginson

I've certainly never heard that one Charley.

I wonder if BDL is small enough in scope for a smaller engine, Peter can maximise the power from one and give massive volume but if the needle is designed to work on 1275 (or more) maybe it isn't optimum for a 1133. A good engine to begin with but not covered in use by the Austin Rover team who had Metro, Maestro and Montego engines in two basic size ranges 1000 and 1300 when they were optimising the A series for the brave new world of the eighties.

I have been looking into the factory data books for info but nothing I have would cover such a size of A series.

The 1.0 litre engines used the HIF38 rather than HIF44 so there's no obvious crossover in sizes.


Searching the MGB Tech archives with all words hif choke rich here is the first one that came up. The link is below and a quote from some if it is below that.


Posted 27 May 2010 at 00:34:48 UK time
Fletcher R Millmore, Pennsylvania, USA,
HIF have tiny O rings in the cold start mechanism; when they die, the "choke" is effectively ON, and you get all the symptoms described. Since the choke effect diminishes with RPM, leaning out will help a bit at/near idle but kill performance and eventually the engine at higher throttle openings.
Rebuild the carbs, with special attention to the cold start.


Posted 27 May 2010 at 02:39:10 UK time
Fletcher R Millmore, Pennsylvania, USA,
Further to my above:
There are two holes in the floor of the HIF carb bore, just engine side from the jet. One is a vent to the float bowl, the other is the cold start discharge port. Start the engine and run it up to 3-4000 rpm, while looking down the throat with a good light. If fuel can be seen issuing from the port, then the O rings are perished or omitted; or the cold start is ON or wrongly assembled.

I first discovered this on a car that unaccountably had little screws installed in the discharge ports, couldn't be started cold. When I took them out I got just what all of you with rich HIFs are reporting.

The other possibility is that the floats have gas in them, causing high fuel levels in the bowls - common on HIF.


C R Huff

I've had quite an eventful day really.
Following Mark O's suggestion I removed the air filter and the hole he mentions was indeed blocked by the carb gasket, the stub stack and the filter back plate.
So. I decided to go for a drive with the air filter off and the hole exposed. Before I had time to come to any conclusions there was a slight clunk from the rear of the car when moving off from the lights and I lost drive. I managed to get the car off the road and found that I could select any gear and nothing would happen except a slight grumble from the diff area.
I phoned my mate and he kindly towed me back home where I confirmed what I thought had happened. Right side half shaft broken. I took out the diff and luckily the broken bit came out easily with no apparent damage to the diff. So before I can get back to the carb I need to sort the shaft. I tried to upload a picture, but even though I resized it to the size I always use on here, it keeps being thrown out as too large. I'll try again later.

b higginson

Bernie I have numerous surplus spare halfshafts if you need them in a hurry, just email me.
mgsmithy@yahoo dotco etc
David Smith

David. Thank you for your kind offer, but I already have it covered. My friend Les Robinson has two shafts and although I won't be seeing him till next week, I can get the rest of it built up and just slot the fresh shaft in as and when I get it.
Thanks again.

b higginson


Arrrgh! Much sympathy! I humbly apologize if it was caused in any way by the sudden increase in torque resulting from my suggestion!


Mark O

Touch wood, I haven't broken a half shaft since breaking two on my Austin Metropolitan many years ago.

I used to drop the clutch on my sprite quite a lot too. Sounds like I've been lucky.

How much difference in strength is there, between the plain end and grooved end shafts?
Lawrence Slater

I've fitted a fresh half shaft so now I can get back to trying to sort the carb out.

After reading what Bill says above, I've done some research on the net and have come to the conclusion that I may be over-carbing the smaller capacity engine. Perhaps I would be better off with an HIF38. All the information I can glean from various sources tells me that the HIF44 is better for 1275 and above and HIF38 for 1.0L up to 1275.

Just to clear up something, Peter didn't set up my engine, he just tested it as it was presented when a few of us went to his place to see what BHP we were each putting out. He only made minor ignition timing adjustments and fitted different plugs, he is in no way responsible for any of the problems I have.

So. Does anyone think that I could be better off with an HIF38? If so, there's one on Ebay that might be worth trying. I can always re-sell it if it's no better.

b higginson

BTW. Here's my broken half shaft. Not pretty is it?

b higginson

To be honest Bernie, me? I'd try a smaller one, I have an idea this will resolve the question

I wouldn't have expected Peter to have got a set up wrong, wizardry seems to describe his ability with the needles on A and B series engines. Glad you cleared that up.

So how much is this HIF38? Ah no, keep it to yourself :)

Good luck.


Bill. There are a couple of 38s on Ebay. A new one, very dear and what looks like a serviceable second hand one at up to now, not a lot of money. Might be worth a try. It's on my watch list.

b higginson

How did it fare with the filter and gasket off the carb?
Mark O

The HIF 38 on Ebay went for a bit more than I was prepared to pay, but I guess others will come up.

Once I had sorted my half shaft, I drilled out the stub stack, filter back plate and gasket so that the hole that Mark mentions is now clear. I also fitted a different needle, a BGW off a Maestro low compression engine as fitted to 1.3 vans. It appears to be a bit leaner than the BDL as I had to richen it up to get it to run right. I'm going on a run with MASC on Sunday so I can do an economy test. The car pulls well and runs smoothly with this fresh needle fitted, but I'm still looking for an HIF38.

BTW I can't find the BGW mentioned on any needle chart to check it and I saw on a Morris Minor forum that someone mentioned that they couldn't find it either.

b higginson

I thought I'd better post the results of my economy test before this thread drops off the bottom of the board.
I got 39.6 mpg with the BGW needle fitted and the driver behind me didn't smell any over-richness. The car ran really well on some pretty challenging roads, so I hope the info will be of use to others with the smaller capacity engines.
Thanks to everyone for your input.

b higginson

The BGW needle profile is

Chris at Octarine Services

That seems a darned good result to me Bernie, we should save this info somewhere...

but we've tried that before :)

Chris, nice to see you back here again

Chris. Thank you for that info. Most helpful.

Bill. Yup. I suppose it will disappear into the depths of the archives never to be found again :-[

b higginson

This thread was discussed between 27/05/2013 and 17/06/2013

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