2" SU's or 240Z carbs?

toopy

toopy

Club Member
Currently have 2" SU's on the car, they've never run that well and its debateable wether they are good enough to be tuned
properly without stripping them down for a rebuild, but i dont want to throw money at them
if theyre really not required.

or

I still have the 240z carbs that were on the engine when it had the L26, they worked fine,
although they have now been lying around for 8yrs or so!

so question is what would you do?

Engine is standard L28 running electronic ignition and leccy fuel pump,
a performance manifold and exhaust (of unknown parentage) are the only upgrades.
Both sets of carbs have the pancake K&Ns fitted.
 
Either way you're going to have to 'throw' money at each set of carbs and ideally follow that up with a r-road session to tune the needles just so.

Are they 63 or 80mm thick air-filters ?

I assume a standard head and cam so your 2'' are over-carburated - the std 240Z carbs'll be just fine.

But....having already bigger carbs and better filters and a performance manifold and exhaust, you have all in place to allow the engine to breath and feed better for more torque and power......except that the engine (via the head and cam) doesn't want to.

However, if you're happy with the std L28, go with the std 240Z carbs.

Here's one we did last year, L28 and std 240Z carbs.
 

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Filters on the 240z carbs are approx 56mm thick

2"SU,s i cant say as the car is now at 4ways, but visually they looked comparable to above, maybe a little thicker

I dont mind spending some money on either carbs, i just dont want to spend it on the SU's
and still find theyre not that great
I guess atleast the 240z carbs are a known quantity to start with

and yes, 4ways will be rolling road tuning whatever carbs i go with

I wouldnt get rid of the SU's, as at some point i would like to have some head work and cam done,
but for now, i just want to drive and enjoy the old girl! :thumbs:
 
I see on the those pics you done away with the fuel rail and return pipework

any particular reason?
 
Just had the dashpots and pistons off the carbs, both cleaned up nicely with carb cleaner
and everything seems to be operating smoothly

I did however drop one of the pistons and it landed on the needle and bent it :eek:
better that than the oil tube thingy i guess!

Phone call to Mr F on Monday me thinks :)

Needles looked ok with no obvious wear marks, but prudent to change anyway, especially now :unsure:

I remember replacing one of the jets years back, but which one :( need to have them off
as well i guess
 
toopy said:
2"SU,s i cant say as the car is now at 4ways, but visually they looked comparable to above, maybe a little thicker

and yes, 4ways will be rolling road tuning whatever carbs i go with

I wouldnt get rid of the SU's, as at some point i would like to have some head work and cam done,
but for now, i just want to drive and enjoy the old girl! :thumbs:
Click to expand...

Those on the white L28 Z above are std 240Z carbs (as stated) NOT 2".

You can still run your std 240Z carbs on a worked head and uprated cam - just change the needles and r-road it (ideally) to make sure that they are right.
 
As a matter of interest has the inlet manifold been 'opened out' for the 2" carbs?

If not it should have been.

If it has then you may need to replace that if reverting to the 1.75" carbs.

As Sean says, a good pair of 240Z carbs should work ok for you.
 
Rob Gaskin said:
As a matter of interest has the inlet manifold been 'opened out' for the 2" carbs?

If not it should have been.

If it has then you may need to replace that if reverting to the 1.75" carbs.

As Sean says, a good pair of 240Z carbs should work ok for you.
Click to expand...

Fortunately both sets of carbs are on there own manifolds

No idea about the 2" SU one being opened out though, but i assume so as they came as a set!
 
Anyone got any pointers as to what needles are best suited to an L28

240z carb needles.jpg
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found the above pic, but i believe there are other needles as well
 
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Downside with 240Z carbs is that nozzles (jets) are not readily available, so first place to check for wear...

I've always sold the SM needle for mild tune upgrades - tried and tested. Available from stock.
 
Mr.F said:
Downside with 240Z carbs is that nozzles (jets) are not readily available, so first place to check for wear...

I've always sold the SM needle for mild tune upgrades - tried and tested. Available from stock.
Click to expand...

The jets i believe were replaced by myself way back, as they look new/clean and the shaft that
sits inside the carb body still has the bright green coating on, so hopefully they are good to go,
I thought id just replaced one but i did that on the SU's so prob just confused.

I will require 2 needles though, as well as the fuel pipes between float chamber and jets, gaskets for
float chamber tops, needle valves,
and one of the bolts that holds the float chamber to the carb body is chewed up so could really
do with renewing, assuming all this available?

Mike, will call tomorrow some time :D
 
Surely if the needles are centred correctly the jets should never wear out??
Mike are you saying that there are no replacement jets available from anywhere?


Mr.F said:
Downside with 240Z carbs is that nozzles (jets) are not readily available, so first place to check for wear...

I've always sold the SM needle for mild tune upgrades - tried and tested. Available from stock.
Click to expand...
 
I believe Ztherapy have jets available, not sure if they are new ones manufactured to there spec or reconditioned originals though.
 
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