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Stock L26 with 240Z Carbs, Linkage, Fuel Rail, Trumpets and Socks too much fuel!


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#1 Bozo

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Posted 28 February 2012 - 10:36 PM

Hello dear Z enthusiasts,
I am currently under a massive dilemma...

My 260Z is currently fitted with 240Z carburetors, E41 balance tube, trumpets and socks, etc. My fuel consumption is still about 160KM's on the full tank running BP/Mobil Unleaded Octane 95... 98 is worse, about 120KM's.


What could be the problem??? Surely this is not the fuel economy of a stock L26...

#2 peter mc

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Posted 28 February 2012 - 10:48 PM

No that's not normal
your carbs need to be looked at most likely worn in the  tubes the needles run in and running very rich  have it checked out by a zed man in melb or come down to Les collins racing , daz in melb will fix it for you if you don't wont to come out to the sticks

#3 Bozo

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Posted 28 February 2012 - 10:57 PM

Had these carbs re-built with brand new kits and brand new hoses... Maybe if I pull the hoses off? Coz I seem to be having a similiar issue with the thread before mine, where if I floor the pedal to full throttle, There is hardly any response, and after flooring for a 10 secs or so and stepping on the clutch - It STALLS!

#4 gav240z

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Posted 29 February 2012 - 12:27 AM

Who rebuilt your carbs for you? Got pictures of them? I've heard of people getting "240Z" carbs that were not in fact 240z carbs.

Your lack of excitement when hitting the loud pedal could be an ignition issue.

What colour are the spark plugs?

Take some pics of these items perhaps? But honestly it's hard to tell you what's wrong without a bit more detail.

- Do you have an electric fuel pump?
- When was the filter changed?
- What kind of distributor do you have stock?
- What condition is the rotor button, points, distributor cap, leads, plugs in?

Engine bay pic would probably be the best.

#5 peter mc

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Posted 29 February 2012 - 07:12 AM

just because some one put new gaskets in them does not mean there rebuilt ...... take it to a zed man and have him look at it

#6 Scoota G

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Posted 29 February 2012 - 08:10 AM

I'm going to say the float levels need adjusting. You should be getting about 380 Kays per tank!

#7 DAZDA

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Posted 29 February 2012 - 08:59 AM

By 240Z carburettors I assume you mean the Hitachi SU-Style carburettors…

Unless there is an actual fuel leak (split fuel line, hole in the tank, etc), excessive fuel consumption with these carbies is usually one of the following;
  • Incorrectly adjusted needle tube height – there is a big mixture adjustment knob under each carby.  Generally, the closer the seat (needle tube) is to the needle the leaner the mixture will be overall, and vice versa.  To get the mixtures 'right' like you can do with EFI would normally require different needle profiles (different needles) but you should be able to get it reasonably close with the adjustment knob
  • Too much fuel getting past the needle and seat – which is usually incorrectly adjusted float levels (too high) as Scoota G suggested
  • Fuel Bowl(s) overflowing – usually one of the ‘floats’ is no longer floating.  I have experienced this a few times with the brass floats.  Replace the float with one that does, reset the float level and this should be fixed


#8 Bozo

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Posted 29 February 2012 - 07:12 PM

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Sexy or wot?

#9 chris240

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Posted 29 February 2012 - 08:00 PM

And while your looking for a zed carbie man, also look for a hairdresser  ;D
I was able to get 400kms plus on hwy cycle.

#10 Lightmaster240z

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Posted 29 February 2012 - 08:31 PM

Tune up with some that know what is going on will make all the difference to the car and the number of a good lawyer is sue who ever cut your hair  ;)
This should fix all these problems.
Bruce 

#11 gav240z

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Posted 29 February 2012 - 09:45 PM

If you're a DIY guy I highly recommend:

The JUST SU's video

http://www.ztherapy.com/

http://www.ztherapy....eos/just_SU.htm

They sent me a copy a while ago and it literally covers everything and is cheap to buy also. You'll know how to get the most from your S.U carbs after watching this.

#12 pauly_adams

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Posted 01 March 2012 - 04:58 PM

well i get 500+ km out of my tank in my 2+2 with a 55L tank so there, what i would be doing is first check your timing, then check your float level, then fuel pressure as it may be miles too high, then check mixture screws what you can do is tighten them all the way in then take them out 3-4 turns make sure there even. after that balance them you can use a piece of 4mm hose in your ear to help you hear the vacume, after all this adjust idle then recheck if you get them sweet you should get awsome power all through your rev range.

hope this helps cheers pauly

#13 MaygZ

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Posted 01 March 2012 - 06:07 PM

If you're a DIY guy I highly recommend:


He is with hair cuts!

... where if I floor the pedal to full throttle .....


There's part of the fuel consumption problem.

I strongly suspect your spark.  How old is that coil??  pull off a lead and check the spark.  It should be able to jump about 5-6 mm easily and be able to be heard and seen during the day.  If you have that - and I doubt it by the look of your coil - then check the heat range and gap of your plugs.  Finally check your dwell and timing.

Once you have all of these spot on, then start looking at your carbs just as Pauly described.

But before you do anything else  .. and this is very important ... before you do anything else what-so-ever .... get a frickin' hair cut!!!  You look like a Bozo.

#14 Bozo

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Posted 01 March 2012 - 07:01 PM

lol.
Spark plugs are brand new NGK Iridiums... Coil is old and I will gladly appreciate a brand new 280ZX digital coil

#15 luvemfast

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Posted 01 March 2012 - 07:47 PM

Yes you have new plugs.
But what type?
From memory, I have 5's in mine.
Your economy is worse than my triple 44PHH Mikuni's  :o

You mentioned you had them rebuilt. By who? They're 1 3/4" right?
This was done as your 2" ones were usin too much fuel right?
See the pattern?
May not be your carb's alone.

Take it to someone who knows what here doing. Do you have Daniel Moore's details?

#16 Enzo

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Posted 02 March 2012 - 09:47 AM

Hi Bozo,
          From your pictures it looks like you are running the N36 inlet manifold with the vacuum fittings behind the first carb. You have 2 hoses attached from the manifold to what looks like the suction chamber air inlet on the face of the carb behind the filters. The suction chamber inlet should be drawing air into the carb at atmospheric pressure. What the picture shows is vacuum drawing against the dampener. Remove the hoses and block off the 2 vacuum fittings at the manifold.
On the diagram No 5 shows the direction of air flow.
Regards
David

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#17 Bozo

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Posted 02 March 2012 - 03:59 PM

If I don't pull them off now, will I cause any damage? Coz I drive it out to work and weekend nights...


Its rendering me so paranoid that I can't even dance properly at the clubs anymore :(


I wanna be  8) again

#18 PZG302

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Posted 02 March 2012 - 06:34 PM

lol.
Spark plugs are brand new NGK Iridiums... Coil is old and I will gladly appreciate a brand new 280ZX digital coil


No need to use the expensive iridiums, the NGK BPE6, or 5 is all you need and only about $5 a pop. At worst you may need to go to a 7 depending on the state of your motor, ie higher compression and the timing you run, but standard motor 6's would be were I would start with plugs.

#19 Enzo

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Posted 02 March 2012 - 10:00 PM

Bozo,remove the hoses so you don't have vacuum at the carb. This should be vented to atmospheric pressure.

#20 Bozo

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Posted 03 March 2012 - 10:19 PM

Just remove all the hoses? Will it improve things like performance and fuel economy?




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