Morris Minor Owners Club

I have just purchased an HIF 38 carb on ebay and it arrived today. I have read through all of the threads here on the HIF 38 but am still confused on the actual plumbing as there are so many inlets and breathers. On my 1098 cc with the HS2 only the rocker breather is connected to the air filter. I also need the bracket to mount the choke and accelerator cables onto the Metro manifold. I checked the mini sites but cannot find the bracket (only for a HIF 44) and the spacer seems to be no longer available. I don't think it would be a great problem to make up a bracket and spacer. Can anybody help or advise?
The HIF also has a large black knob on the side-what is that for?
Any particular literature that I should purchase? All I have is the exploded view on the SU website. What is the procedure for checking the needle as I don't know what needle is in there? Any pitfalls to avoid?
I would appreciate any tips before I start taking it apart.
Thanks
Declan

I would think the bracket and spacer from a 44 would do the job. Needle out is easy enough to do. Just remove the dashpot and the needle is held in the piston with a grub screw. The ID should be on the top shoulder (the bit that fits into the piston). Not sure what you mean by a black knob (a picture might help). There is the usual fuel in, breather and an overflow port on the 38.

I think the black knob is the housing of a filter element that covers up the float chamber breather.

Yes - it's a breather. Should be a largish tube on the side to take the breather from the rocker cover - and a fuel inlet pipe. I'll take a picture tomorrow of my installation if you like. And - AAA needle works well, but wait to see what's in yours alraedy - it's a 2 minute check.

Thanks,
I'll remove the needle tomorrow morning and post a picture of this "black knob" breather.
Declan

Hope this helps

Although there are a number of different versions of the HIF type carb, they all essentially share the same type of connection layout.

The diagram below depicts the most common type - the connections can be on either the right hand side (as illustrated below) or the left hand side. Some have the connections shared on either side. Whichever, the port functions are the same.

It isn't essential the crankcase breather pipe be connected - you really don't want that choking crap from the crankcase spoiling your nice, fresh, fuel-rich incoming mixture - but it's obviously essential to block the port off if you don't. A blob of RTV Silicone is sufficient in most cases.

To adjuster mixture - screw the adjuster in to richen, out to weaken. There may be a 'anti-tampering' cap in there on some carbs - just hook it out.

On some HIF carbs - predominantly used on later Ital (Marina) and Maestro A+ low compression engines - there can be a black hose looped from a port on top of the carb to manifold flange to the float chamber breather/overflow port. This is a leaning-out device for when running at cruising speed on small throttle openings. This needs removing before it's really useful on tuned Minis. Just block the flange-mounted port off, and breath the float chamber to atmosphere as normal.

Unlike the H and HS type carbs, the choke circuit is controlled internally by a special port controlled by a tapered spindle - so there's no messing about with choke linkages needed. Simply connect the cable up.


<br><br><br><br>
1 - FUEL INLET PORT
2 - FLOAT CHAMBER OVERFLOW/BREATER
3 - CRANKCASE BREATHER PIPE CONNECTION
4 - FUEL MIXTURE ADJUSTMENT

I have removed the piston as shown in the picture below, I have also removed the grub screw. The little collar where the needle goes into the piston slides but does not come out. Am I doing something wrong? Should the needle (seems spring loaded) and collar simply pull out. I didn't try to force anything-I' rather ask first.
The second picture shows this black "knob" I was enquiring about.
Thanks
Declan<br><br><br><br>

BTW thanks Kevin and all concerned, I think I understand the plumbing issue-the picture/diagram is a great help-just can't figure out how to get the needle out of the carb.
Declan

Got the needle out by prising the sleeve gently- After I eventually found my magnifying glass and asking the domestic authorities for a second opinion-it's an ADS needle. Shall I order the AAA or just try the ADS?
Thanks again for all the help.
Declan

PS Anybody got a carb spacer/bracket to sell?

If you're replacing the needle it's probably worth replacing the jet as well. They tend to wear slightly oval from the spring-biased needle and that makes the idle mixture a bit rich. I really should do that with mine as it smells rich at idle but still returns around 40-45mpg.

BTW, your carb looks exactly like mine (which was from a 1.0L Metro), same black "knob" on the float chamber breather and same part-throttle leaning-out pipe. I've heard people say bad things about this pipe but I've had no problems at all, but I'm after economy rather than out-and-out power.

I've got the crankcase breather connected to the front tappet cover pipe. Remember that low crankcase pressure equals low oil consumption.

Thanks Stig,
Is this the jet? Easy to replace?
http://www.minispares.com/Product.aspx? ... 20JET%20HI...
Declan

That looks like it, yes. I imagine it's fairly easy to change, but I've not done it myself (yet. I really should sometime though). I'd guess the only tricky bit might be to get the jet height correct.

Hopefully someone else has done it and can enlighten us.....

ADS - 890 850 838 811 768 739 709 691 682 665 650 640 627 616 603 590
AAA - 890 850 814 785 755 720 674 630 600 580 560 540 520 500 480 460
So - the ADS is a VERY weak needle. If you have good facilities - and a micrometer - you can of course carefully machine the ADS needle down to the AAA profile !
I can only say the AAA runs well for me on a similar engine set-up to yours. It's probably not going to be exactly right - but it will be a good starting point. I wouldn't bother changing the jet - wait and see if it runs ok as is.
The fume pipe should be connected up to the car - better the engine eats it's own fumes than the breathers blow it out - and you breathe in the carcinogenic particles ! The suction also helps to keep oil below the rings - and minimises oil leaks. Yes - there may be a very slight reduction in the clean air going into your engine - but it's a small penalty to pay compared to the advantages.

Thanks BMC, I will pop over to a local Mini/BMC dealer and see if he has any carb bits-he might even have the AAA needle. I think I understand the plumbing set up but could you post a picture of yours just for reference if you have the time?
Thanks
Declan

If you have good facilities - and a micrometer - you can of course carefully machine the ADS needle down to the AAA profile !

So that explains why a piece of emery cloth with the needle in a drill chuck didn't work to well I suppose

Emery cloth will take some metal off - and I suppose if you have the patience you could 'emery' the ADS above down to AAA shape - but there's quite a bit to take off!

I have the same HIF38 as you, it's from a Metro i think. It actually has an economy "feature" that weakens the mixture when at mid-throttle light loads. I had to plug those breather pipes up to get it working properly.

I was using an AAU needle with a 1098 (12G940 head) and it was never right. Very lean at mid throttle under light loads.

I recently took it to Mikeanics Motorsport in Congleton and had it tuned on the rolling road (£100). He had to heavily modify the needle to get the fueling right, but now it's running very well.

57Bhp @ 5500 rpm, 63 ftlb @ 4500 rpm.

That's with the following setup...

HIF38 on alloy inlet
1098 block
12G940 Head with exhaust seats recessed.
Maniflow small bore exhause
123 Fully mapped distributor

That sounds about right. Which program are you using on the 123 winger ?

Hmm, strange that your carb needed such modification and mine seems OK. Not perfect, I'm sure, but no flat spots etc.

I'm running an unmodified HIF38 (1.0 Metro) on an alloy manifold (MG Metro) with a larger bore exhaust on a 1098 that's standard apart from 1.5:1 rockers (they were free).

I'll have to check what the needle is sometime.

Does it go significantly better than standard ?