Mixture adjustment screw

Post by **KirstMin** » Mon Oct 31, 2005 12:44 pm

OK, it was late and getting dark when I tried to adjust the mixture on my car and I gave up - they dont seem to put the mixture adjusting screw in the same place on the HIF44 do they?

is the damn thing at the back? Is it where ive circled?

ta

Post by **Matt** » Mon Oct 31, 2005 1:03 pm

I think it is, but i would like to know this for certain as well....

Post by **KirstMin** » Mon Oct 31, 2005 1:08 pm

For some reason (and not having a diagram) I just assumed it would be in an obvious position; not hiding at the back! Wishful thinking I guess. Anyone know for sure?

Post by **Packedup** » Mon Oct 31, 2005 1:45 pm

It's a cross headed screw buried in a recess.

From the carb side of the engine, look about half way between the top of the carb body (going from the join with teh dashpot) and the bottom (where the float cover plate is), on the right. You should find a recess, exactly where you've circled in that picture. In there is a small cross headed screw. That's your mixture

I'm used to having them on Metros and Minis, where you soon get used to knowing where it is by feel - Mainly because it can be a nightmare to actually see!

Post by **bigginger** » Mon Oct 31, 2005 1:59 pm

Directly under the petrol inlet, I've read whilst googling.

Post by **KirstMin** » Mon Oct 31, 2005 2:26 pm

OK, thanks both. I'll give it another go tonight in the Tesco's car park where I can see better

Post by **bigginger** » Mon Oct 31, 2005 2:40 pm

I've got to do mine too - keep us posted on the job/finding it!

Post by **Onne** » Mon Oct 31, 2005 4:58 pm

But do watch out, apperently it works the other way round. So in is richer out is weaker, but please do correct me

Post by **Skeggysteve** » Mon Oct 31, 2005 6:10 pm

From the depths of my memory I seem to remember the HIF's, probably other later type SU's as well, had the mixture screw hidden behind a little plug so you couldn't see the screw head. Or find it when poking a screwdriver around!

Pretty sure you have the right place circled, but please let us know!

Post by **wibble_puppy** » Mon Oct 31, 2005 6:13 pm

ooh i want to know that too

please post some more excellent pics when you have found out all about it for sure KirstMin

juliet xx

Post by **Packedup** » Mon Oct 31, 2005 6:23 pm

Some carbs did have the screw covered - "Tamperproof" so you couldn't mess up teh mixture and be an envirnomental nightamre. Also of course meant you couldn't tweak the mixture to suit the characteristics of your engine, till you reomoved the cover...

Not sure the HS had that though - Be quite tricky as the adjustment is through moving the jet carrier/ bearing up and down with that large nut.

But on the HiF, that little screw ringed on the picture is the right one - It presses on a metal plate inside the carb that moves the jet up and down. I think Onne's right it's in for rich and out for weak, but I can dig out my Metro Haynes and double check that later if needs be

Post by **aupickup** » Mon Oct 31, 2005 7:09 pm

hi

this link will expalain all you need to know about the hiff carbs and ital crankcase pressures etc.

hope it helps

http://www.minimania.com/MM/SU_CARBS___ ... pe_763.htm

Post by **bigginger** » Mon Oct 31, 2005 7:22 pm

I spent an age on that very site trying to find a diagram that said all that and failed...

Post by **Cam** » Mon Oct 31, 2005 11:15 pm

Yes, it's just below the fuel inlet on a HIF44. It's also (annoyingly) on the rearward facing side of the carb in an in-line installation.

Post by **Packedup** » Mon Oct 31, 2005 11:43 pm

At least you should be able to get at it with a normal screwdriver on an inline - On the transverse I had a stubby crosshead I kept in the glovebox as all my normal ones were too long to get in the gap.

Post by **Cam** » Mon Oct 31, 2005 11:48 pm

Well, you SAY that, but I've had to use a short-ish screwdriver before now as a you can't use one that is TOO long 'cause you hit things that are in the way! (much easier than the transverse though).

Post by **Matt** » Tue Nov 01, 2005 12:08 am

Funny you should say that cam but what do you think i was trying to do on the motor club mini the other day? yup trying to adjust the Hiff44 with next to no clearance!

Post by **KirstMin** » Wed Nov 02, 2005 10:55 am

OK, it doesn't matter if it is dark or light because the screw is so fiddly you have to do it entirely by feel anyway

I've not had too much luck making the mixture adjustment. I have turned the screw fully both ways and stuck with the point where the revs are the highest. But there isn't a great deal of rev range apart from it dropping off at either end of the spectrum - it's fairly subtle - is this normal?

The upshot of it is that the car is still running very lean; the choke 2/3 out remedies the problem and I get a nice powerful acceleration. So I am now thinking that it is the wrong needle? Even though it's the needle that Birmingham sold me with the carb and air filter

However, in 2 weeks I am changing the camshaft and cylinder head and then taking the car on the rolling road so I’m not sure that there is much point in me spending a whole lot of time sorting this out BUT, what is the best way to run the car in the mean time? eg: is it better to run with the choke out to the point where I am getting best performance or run with it lean? Am I going to do any harm in the next few weeks if I drive with the choke out - should I get it sorted before the rolling road?

Thanks knowledgable peops

Post by **Cam** » Wed Nov 02, 2005 2:55 pm

Well, as long as you are not getting 'pinking' things should be OK. You CAN run with the choke out (partially) for a little while, but it will start to coke things up after a while. Probably OK for 2 weeks, but it depends on your mileage of course.

Post by **KirstMin** » Wed Nov 02, 2005 3:01 pm

As I don’t really know what 'pinking' is I'm not sure if I'm getting it or not!

What I do get when I accelerate is the car feels like it is being pulled back, like it’s dragging it’s feet, stuck in quicksand as it were!

I’m supposed to be doing a 300 mile round trip on Friday so I’ll keep the choke in then!