Twin Su Carbys

[Smithius]

Here's the deal...

 

I have just purchased a set of twin inch and a half su's on a manifold of ebay and i would like to know any particular tricks or information about setting them up.

 

I have messed around with different jet sizes on webers but i have never had and expeience with su's or any twin carbys for that matter.

 

Any help would be greatly appreciated.

 

For the moment they will be going on a stocka 3k (i know its overkill but i love the noise) but they will be going on a tuff cammed 4k that I'm in the process of building now.

 

here is a pick of the pair. i know they look dirty but they will be getting a rebuild before fitment.

 

Cheers

Mattew

[Taz_Rx]

Kangaroosa might be a good person to talk to about SU's mate! :jamie:

[Smithius]

ok cheers Taz ill see if i can get a hold of him

[philbey]

mind if I ask what you paid?

 

I was looking for a set but ended up with twin dellortos instead. I have a bunch of info that I dragged up from my searching at home, will post up later.

 

It has info on needle sizing/shapes etc and how to tune and balance them.

 

also, its probably likely you will get poxy performance and use heaps of fuel in the mean time on a stock 3k. but they will sound cool!

Edited February 19, 2008 by philbey

[Smithius]

i got them of ebay for a pricely sum of $77.76 on the manifold. I just finished rebuilding them myself today and they have come up sweet. Rebuild kits cost me about 50 each with new oversized throttle shafts. Just have to rework the linkage setup and ill put them on.

 

The info that you have would be greatly appreciated

[kangaroosa]

mind if I ask what you paid?

 

I was looking for a set but ended up with twin dellortos instead. I have a bunch of info that I dragged up from my searching at home, will post up later.

 

It has info on needle sizing/shapes etc and how to tune and balance them.

 

also, its probably likely you will get poxy performance and use heaps of fuel in the mean time on a stock 3k. but they will sound cool!

 

I've got a needle sizing chart/book that lists all the available needles and their dimensions along the shaft, Came in quite handy when setting mine up. Its called "Carburettor Needle Profile Charts" by 'Burlen Fuel Systems'. I got my copy on ebat from a UK shop.

 

For anyone else setting up SU's, i found Automatic Transmission Fluid worked better than engine oil in mine.

 

$78 is a bargain. I sold mine recently for ~$500 on the manifold with linkages.

[philbey]

Sweet mother of god, that is a ridiculous price. I haven't been looking for them on Ebay lately, and if I had been you wouldn't have got them at all, after I lost the bidding war on Kangaroosa's a while back!

 

Here are a couple of pages for you, mainly on the operation etc:

 

Some Tuning etc

 

Operation Principles with good diagrams

 

I do know of other sites, some were quite hard to find. I have the link on one of the many computers I use....

[Davros El Davros]

Hey man,

 

Thats sure is a sweet price for your setup.

 

When I was looking at rebuilding my SU carbs, I found this book:

 

Autobook World

 

 

It is basically all you need to know about rebuilding and tuning your SU Carbs, plus some race tuning advice to make em go harder.

 

 

They are sweet carbs when you get them set up properly - really simple design that produces great results.

 

 

Good Luck!

 

Davros

[Rollaboy2608]

My previous experience with SU's are that they are extremely unreliable, and get out of tune very easily.

Having said that, this was on a 1960 something XJ Jag, but the carbs were freshly rebuilt. Just got the tune right then it would come back running like a dog couple of months later.

[Xany]

Never had one issue with mine since they were setup correctly by my carby bloke. Nicely tuned and idles just right. :P

 

I think the operative word in your post above would be "Jag".....

[philbey]

Everwhere I looked when researching twin carb setups, I found just as many people canning setups as those who praise them.

 

This goes for SU's, Dellorto's, Solex's and admittedly to a lesser extent, Webers.

 

I'd suggest you rebuild them (as you've done), read up heaps about them, learn to setup, tune and balance them yourself and if they still give issues, pay someone to do it.

 

Pending that, if you don't like them sell them to me for 177 bucks!

 

Not doubting your input Rollaboy, but I found overall that peoples experience with these matters varied so broadly that the only thing to do was buy em and try em!

[Rollaboy2608]

yeah I guess, and to add to that, each carby seems to have almost its own "personality" whether rebuilt or not.

Over time parts change their behaviour e.g warped throttle butterfly shafts etc, which can be hard to pick up on by the untrained eye

[Smithius]

Ive been in sydney for a week so havent had time to play. I was wondering how people got the throttle cable to work properly as the linkages were crap and didnt come with that part.

 

Any ideas?

 

Photos?

 

Cheers

matthew

[Raven]

if you're good with a welder, weld on the throttle wheel from a K-series Aisan carb :yes:

[Smithius]

ah the problem with that is the su's work the oposit way to the asian.

 

thanks for th wheels by the way. got the rubber off today going to grit blast them during the week and hit them with some paint