SU Carb attachment

[Hovis]

What is the best route to attach my newly purchased SU carb to my engine? I've looked at a few.......

http://www.sj-uk.co.uk/page23.html £110

http://www.adksuzukispares.co.uk/page38.html £175

http://www.rhinorays.co.uk/engines.htm £150 and old manifold (at the bottom of the page)

Are any better than the others or do i do the scrooge thing and just buy the cheapest!

Do they give more power than a webber or is the ability to go almost upside down its only advantage?

[V8MoneyPit]

Most conversions are just an elbow to bolt onto the existing manifold. Like the first two. The converted manifold is rather nicer in principle.

I had to modify a fabricated elbow on my Spanish Sammy to clear the servo hose from the manifold. It would be rather more difficult with a cast one, but it does look much nicer.

The Weber can suffer from fuel starvation on side slopes, etc. The SU seems to cope without any trouble. I haven't noticed any significant performance improvement over the original carb (apart from running fine when cold which it never used to!).

Most people, including me, seem to get a BDL needle to work fine in the HIF44.

HTH.

[Hovis]

...

Most people, including me, seem to get a BDL needle to work fine in the HIF44.

HTH.

BDL needle? Excuse my ignorance :oops:

I thought the manifold route looked good, just think it'll be a lot more hassle and i wanted to fit it at the weekend.

Looks like it's going to be the ADK route anyway. SJ-UK haven't managed to answer the phone all day, respond to a answer phone message or either of the e-mails i sent. Wish i could business like that!

[V8MoneyPit]

With SU carbs you change the needles to get the correct mixture across the rev range.

There is a jet tube in the base of the carb. Then there is a tapered needle in a piston that lifts as you open the throttle thus allowing more fuel in to compensate for the extra air passing through.

The mixture adjustment screw moves the jet up and down to get the mixture set at a specific needle position, usually idle. But if you imagine the needle is thinner at the tip than required by your engine, it will be too rich at high revs. So a needle with a different taper profile would be required.

I am assuming you have an HIF44 carb? This is the type with a large square base. Remover the 3 screws holding the dashpot (top section) on. Carefully lift this away. The needle will be sticking out the bottom so careful not to bend it. You will find a grub screw in the side of the piston. Slacken this off and the needle complete with it's grey carrier can be pulled out. Slide the carrier off and you will find an ident stamped around the top of the needle. This will be something like BDL or BDK, etc.

Does this make sense? Difficult to describe without diagrams  :lol:

This is my Zuke set-up although it now has an air box for the filter and a snorkel.

[Hovis]

That does make sense thanks very much. It'll be safer if I leave the mechanical stuff to the 'Team' mechanic, Martin, i think!

Is one needle type better than the other?

[V8MoneyPit]

Not a case of one being 'better' that the other as such. A correctly set up carb will require a specific needle type to suit a specific engine. All engines require a 12:1 or 14:1 air to fuel ratio (can't remember the exact ratio). The job of the carb or injection system is to provide that ratio across the rev range and load range.

The BDL just seems to work quite well with the 413 engine. It may not be perfect and only a rolling road session will get it spot on. You could have 2 apparantly identical engines and they could need different needles. Just because of slight port casting differences, CR differences, etc. But as long as you don't want to squeeze out the last hp or mpg, close enough is good enough!

[Hovis]

MPG is not an issue really and who needs more power than a 413 has to offer?! :lol:

[V8MoneyPit]

Exactly!  :lol: Check the needle in the carb you have and if it's a BDL, bolt it on and try it. You will need to tweak the mixture screw to get the emissions to MOT levels. Then take it for a run and see if it runs OK. After a blast down the road check the colour of the spark plugs to make sure it's not over lean at high revs. If they are a nice tan colour, all is well.

[generation-x]

hovis your have better luck gettin intouch with tim weston @ rhino-central as he has merged with sj-uk
he will be able to answer ur questions about the su conversion
or ask me lol

simon

[V8MoneyPit]

No disrespect to Tim, but it was a Rhino Central one I fitted and it wasn't exactly brilliant quality..... and it needed modifying to fit my car. I did speak to Tim about it and he did take note of what I had to do. So the product might be a little different now.