British su's

[zzzzed]

I have a set of British su carbs on an L series manifold. Would these be better or worse than the standard flat top hitachi carbs on my 260z. I am thinking of putting them on

[Scoota G]

Bozo (Sam) was running them. I imagine it would run much like a Jag 

[C.A.R.]

They'll be fine mate - just bolt 'em on & get it tuned

[zzzzed]

Bozo (Sam) was running them. I imagine it would run much like a Jag 

So it will develop wiring issues then I just went to look for them in my shed but havnt found them yet. I know they are there some were.

[lightmaster240z]

There on the other side of the shed next to that thing you put down the other day. You know

[zzzzed]

Thanx Bruce. Must be with the flux capacitor. 

[Riceburner]

Lucas electrics=The Prince of Darkness 

[53-681]

Yeah I ran them for a while - heaps of hiccups and flat spots... I've had nothing but bad experiences with'em.

 

From what I've been told - If tuned correctly they will be awesome, but even so they don't hold their tune as consistently as the hitachi su's

[chris240]

I bought new HU6 pommy carbs about 5 years ago ran them for 3 1/2 yrs and they where excellent. They where tuned just once when installed and where not as finicky as the hitachis. Mind you the hitachis where made in the early 70's and the HU where built in 2006....yes they have improved dramatically in 26 years ! It does help when you buy new also. I still rate the pommy su and HU series pretty good.

[luvemfast]

Sam's linkages were up the sh1t.

That's why he had no joy. The British SU's will be great once set up correctly.

Plus, will only take a few hours to swap over.

[chris240]

Yep, doesnt help when linkages are gonski.

The linkages really need to be balanced, alingned , and allow the carbs to work in perfect sync.

Somewhere on hybridZ I saw a pic of a setup where the linkages where ditched in favour of a cable and bracket that pulled the twin su's right down the middle...ie at right angle to the rocer cover. We seem to do it for tripples but never for twins.

[1600dave]

If tuned correctly and in good condition they will be awesome, and will hold their tune as consistently as the hitachi su's

 

The biggest problem with any SU's (British or Jap) is wear in the throttle shaft, allowing air leaks which upset the tune. People whack a set of SU's onto their car that started life on a Triumph / etc in the 60's or a Datsun from the early 70's and expect them to work just as well 40-odd years later as they did when new.

 

Get them repaired, get them tuned, and they will work beautifully. You can't get a much simpler device than the old SU.

 

I had a pair of 1 3/4" british ones re-bushed recently, cost me under $100 for the job including postage to CSC in Burwood, Sydney. Parts are much cheaper and more readily available for the pommy ones as well.

[Enzo]

Hi Guys,

          I also have a set of 2" Jag SU carbs on a manifold that I tried once. Throttle shafts didn't leak and it idled better than the old Hitachi/SU's, but the needles were as thick as broom handles. Ran too lean off idle. Anyone know what numbers/letters would be on the needles for a good starting point in a worked 260z.

David

[Nobody]

SU carburettors should work fine, if they are:

[*]in good condition - no shaft play, which nowadays would most likely mean they have been rebuild with stainless sleeves for the throttle shaft, seeing as they are decades old now

[*]jetted correctly - this would require a dyno tune and rejetting from somewhere like these guys http://www.bandmfuelsystems.com.au/, unless you have an accurate wideband A/F meter fitted, whereby you could try a few needles and monitor stoich while someone else drove the car through the full range of load

[*]lubricated - they have particular oil which needs to be regularly checked and refilled, because the piston needs to glide up and down without any interruptions

 

To the best of my knowledge you can put big SUs (or any other constant velocity carbies, be they Strombergs or Hitachis or whatever - there are new very slimline versions designed for bikes which obviously don't need reconditioning) on any engine, because they only flow as much as the engine needs i.e. too big and you have spare capacity for better breathing.

 

So a 2"Jag SU would be ok if the three tuning issues above were addressed. Additionally, the 2"s look great - they're huge. I was going to fit one to a supercharged Holden 186 engine, but sold the car. I had it fully recoed here: http://www.thornburycarburettors.com.au/. Looked like a good job.