SU carburettor installation - more information

[Mattzuki]

Here's some additonal SU carb installation information for the forum, and I hope it helps to increase the knowledge base. You should read this in conjunction with Nigel Head's excellent write up, and I owe him a huge thanks for his help during my conversion.

First, the SU carb itself. Follow Nigel's write up - take your newly acquired SU and strip it, clean it up and sevice it with new parts from Burlen Fuel Systems (burlen.co.uk). I also made a gasket for the dashpot (no longer available from Burlen) just to make sure it is sealed properly. Again following Nigel's write up - make the adaptation to position of the idle advance spigot on the carb body. Make sure you retain or get hold of the original throttle cable bracket for re-use. Cap off the vent pipe nearest the butterfly. Choice of piston spring and needle will depend on engine size and set up (more at the end).

Next, remove your old Aisin carburettor. I marked up the hot water flow and return pipes for later use...



Here's where you find out about the variations in manifold designs. If your manifold that looks like the one in the picture below with two holes at the back you can use the left hand one (marked green) as a feed for coolant into your adapter water jacket - this is Nigel's and is a Vitara 1600 manifold...



The picture below is my manifold (Santana Samurai 1324cc). You will see that there is only one hole centre back (marked red), also found on Nigel's type of manifold). This is a breather hole feeding directly to the cylinders. Whatever you do, do not make my mistake of thinking this is a coolant feed to your adapter - you will be sending water straight into your cylinders ! Use the indicated spigot to the left instead.



Next manufacture or obtain your adapter (finished & installed pictures at bottom). Mine was made by my father-in-law to a design almost identical to Nigel's, with the water jacket to prevent icing up. I drilled, fitted and soft-soldered spigots for the coolant feed and return, both 8mm. Also, it is very important to make sure that the faces of the mating plates on the adapter are absolutely flat - the welding process will have distorted them, and you have to eliminate any source of air leakage. Time spent getting this right will save you alot of trouble later. You can get SU/adapter gaskets from Burlen, and you will need to make your own for adapter/manifold.

Then prepare your manifold inlet point to suit your adapter. Cut away as much metal as you are comfortable with...



Time to put it all together: fit the adapter and gasket on the manifold. Fit the SU, not forgetting the throttle cable bracket and gaskets. Connect the coolant flow and return pipes to the adapter water jacket. Connect your fuel line, fuel overflow pipe, throttle cable and choke cable. If you are lucky the existing throttle cable will fit with a bit of jiggling, you will need a new choke cable. Fit the vacuum pipe between the dizzy and the carb.


Important note: the hot water feed in this picture shows where I went wrong and fed water to the cylinders - don't do it! The pictures below show the correct installation for this set-up.

If it's all gone well you should now be able fire it up and enjoy the fruits of your hard work, not to mention blood, sweat and tears. You will have to make adjustments to the fuel/air mix and idle speed and get it tuned right.

You will also need to connect the air filter to the SU. It is important that what ever you use allows air to get to the carb piston via the two holes on the carb face (marked on the picture above). I made my own adapter so I could re-use the K&N filter.

This is what my finished set-up looks like...





There's a huge amount of information available on the internet to help choose the best set up for your SU, how to tune it and what needles to choose. Much depends on engine capacity, manifold and airflow & filter to the carb. My SJ is a 1324cc with a K&N filter so I have used a red sping with a BDK needle. I found that the BDL needle gave flat spots under acceleration. The BDK was recommeded if you use a K&N cone filter (MiniMania website), and now the engine revs and pulls smoothly without using noticably more fuel.

Was it worth it? Oh yes. The engine now warms up more quickly, revs more freely, and even with the BDK needle initial results indicate less fuel use, the engine sounds better and the exhaust note is sweeter. Also, it has got rid of the issues with the Aisin carb.

I hope this helps anyone thinking of installing an SU.

Matt.

[Nigel Head]

Excellent write up Matt, and you owe me nothing.

Good to actually see the differences over my write up using a Vitara 1600 manifold/setup and yours using a 'standard' 1300 manifold/setup.

Nat, this needs putting in the stickies !

Nigel.

[Mattzuki]

Thanks Nigel.

It's nice to be able to give something back to the forum and all the Differs. Give me a shout if you think anything needs adding.

I read your and Nobby's comments about needles, and I did a lot of comparison work with WinSu too (I've copies of the same graphs and many others). I'm going to stick with with the BDK for the moment and get a Gunsons to check it. Then I might (should) invest in a professional tune up...

I've got some useful SU information downloaded into pdf format if anyone's interested - servicing, setting up, tuning etc.

Matt

[Munkee]

Excellent!

I've almost finished my adapter (I work slooooow!), but will be posting exact (ish) dimensions of an adapter that clears the bonnet and spanish (larger) brake servo. Should mean that ANYONE should be able to make, fit and sort an SU conversion!

The adapter will looks strangely like Nigels and Matts (I wonder why?), so I'll take no credit for the design.

Cheers Guys!

Munkee

[BazzWorx]

Hi I'm doing an su conversion on my 413, in the write up the PCV valve has been removed and blanked off. What do I do with the wires that go to it?

Many thanks

Ben

[Mattzuki]

The PCV is the valve sticking up at the back of the manifold and should be connected to the rocker case breather.

Do you mean the valves on the front edge of the manifold?

Cheers,

Matt

[BazzWorx]

Yeah it was the PCV on the back of the manifold, got it sorted after following a few links from other threads. Needless to say you were right.

Thanks very much for getting back to me and for doing the write up in the first place, it was really helpfull.

Thanks again

Ben

[Mattzuki]

Glad to help out.

Matt

[ktomkow]

why does my manifold look different to yours ie why is my vent to cylinders already blocked off and what is that hole in the left hand side for???

[ktomkow]

also can anyone help with why my SU looks different to everyone elses???

thanks in advance

[mnl]

ktomkow, the silver plate sticking up from under one of the vacuum chamber screws has the part number on it, what does it say?

[Mattzuki]

Do you know what vehicle it came off? There might be a little tab somewhere on the carb with a reference number - if you've still got this give the Tech department at Burlen Fuel Systems a ring and they'll identify it for you.

On the photo of your manifold it looks like you might have a spacer plate - see if that comes off. Then you should see the normal holes underneath. (I could be completely wrong though...)

Cheers,

Matt

[Twiss]

One of my friends has this carb, but it doesn't have a tag. I would be interested to find out what type it is...
as there seem to be too many pipe connections!

[ktomkow]

Hi just got in touch with the guys from burden (very helpful) apparently it is a kif38
So does anyone have any ideas on whether it will work on a 413 etc or is it back to flea bay?

Regards

(burlen even) lol

[ktomkow]

just seen this on fleabay seems too good to be true, if it is bad how much would it cost to refurb?

http://cgi.ebay.co.uk/ws/eBayISAPI.dll?ViewItem...ame=STRK:MEWAX:IT

[Kitesurf]

[Mattzuki]

Don't know about that eBay item - I've not heard of a stepper choke before...perhaps it's some kind of auto choke SU used? Personally, I prefer the manual choke on the standard SU's.

A quick trip to your local breakers might help. Look for Metro 1.3s and Montegos (?). Just have a small ruler with you to measure the air intake diameter to make sure it's 44mm.

The new service bits don't cost much from Burlen.

Cheers,

Matt.

[mnl]

I had one on my 1600 Maestro. The first thing I did was throw the stepper choke away and fit a manual choke conversion. They used to be easily available and quite cheap.

I just had a firk around the garage shelves behind the old paint tins, but I must have thrown the choke unit away sometime in the last 25 years.

From memory it was a tube about 12mm diameter that pushed into the carb with a cross hole. The stepper rotated a peg with a cross hole that opened and closed the passage across the tube, and the manual conversion just provided a new tube and rod with a lever on the end that the cable fitted.

Aren't there any metros in the scrap yards any more, they should have an HIF6.

Edit, seen the post above, montegos are like rocking horse droppings now, they were real rotboxes. Pity, the MG Montego I had was a brilliant car apart from the rust that is.....

[Nigel Head]

An HIF6 is a 1-3/4" carb (or 44mm in new money).

SU measure their carbs from the standard 1 inch and nominate them by how many 1/8" inches over standard it is.
So, an HIF6 is 6/8ths of an inch (3/4") over the standard 1" = 1-3/4 inches -- simples !

Haven't seen a Montego or old skool Maestro in yonks either
Probably easier to get a pair off an old Rover V8 and put the one you don't use on eBlag.

Nigel.

[horsethief]

I used the above write up and links,to do my su conversion.Used a su (hif 6)from a rover V8,air filter from a rover 416tc.Got the pair of carbs on a rover manifold and used the left one as my suzuki throttle cable fitted,runs and sounds good,uses less fuel as well.Info fron the burlen site is great.All the info you need is available on here and http://www.sucarb.co.uk/.this is my setup

[4x4madness]

very nice write up, i will be using this tomorrow to sort my su out.

one question though: what did you do with the auto choke cable that plugged into the old aisian carb?

[4x4madness]

why is my SU diferent? the fuel intake is on the oposite side to yours and mine is the hif44? i don't understand

[clbarclay]

Different engine layouts require slightly different configurations of HIF 44 carbs. Yours may have come from a V8 engine where the crabs are back to back and handed so that fuel inlets end up facing the way. Mine is and as a result the choke and throttle connections are also on the other side to the pictures above, it will still fit, just needs a slightly different routing of fuel hoses and controls.

[4x4madness]

ahh ok that makes sense, thanks for the reply. also not to be anoying but how did u block off the 2 little pipes on the intake manifold, do they screw out? or did u have to drill them out and tread a bolt on? sorry im new to all this and just trying to learn

[Russ24]

[clbarclay]

The rover V8 is a good example where two slightly different SU HIF44 carbs can be used back to back so that the throttle + choke linkages end up on one side and the fuel lines on the other.

Some pics about halfway down this page
http://www.v8forum.co.uk/forum/viewtopic.php?t=...05e6ff3365e581ffb

Both carbs on that engine are HIF44s with the same basic components, just the location of fuel connections and throttle linkages tailored to suit the application.

A HIF44 is the simplest to use on an Suzuki I'm aware of, the HIF type SU carbs don't have the float chamber sticking out the side like older types of SU carbs had, its integral on the bottom of the carb instead. The 44 refers to its size (44mm) which is about right for a 1.3L engine. The HIF6 is also the same size (just to be confusing), but the 6 refers to the traditional sizing system used by SU which equates to 1 3/4" which is the same as 44mm.

IIRC the later Minis and Metros with the 1275 engine were a common source of HIF44s like the one at the start of this thread, with the fuel connections and throttle linkages like the one pictured

[Twiss]

Mini ones are easiest for sure, because all of the linkages are on the right size... and it's very easy to find a throttle and choke cable bracket...