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Help - Running Very Rich. First Time Tuning a Car


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#1 Herbonius

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Posted 14 November 2012 - 06:33 PM



A cross post from my build thread -- I need some input

A video walk through of my car showing the body, interior and most importantly, my engine issues. I've never worked on a Zed before and have fairly limited mechanical knowledge. Look at the condition of the car and speaking with the previous owner, I can't imagine that the carbies on it are worthless and I'm assuming that it all just needs a tune.

Does anyone have any thoughts on what to do to stop it running so rich? Do I really need to switch to 240Z carbs?

#2 Gyra

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Posted 14 November 2012 - 08:25 PM

Hi mate, nice car!
Have you tried winding the jets back up a touch?
Also check that the "choke" mechanisms aren't stuck while your there.
Could also be a stuck float in one of the carbies - but better to try the easy stuff first.

Also, how do you know it's running rich? What colour are the spark plugs after a run?

G

#3 Herbonius

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Posted 14 November 2012 - 08:52 PM

Hi mate, nice car!
Have you tried winding the jets back up a touch?
Also check that the "choke" mechanisms aren't stuck while your there.
Could also be a stuck float in one of the carbies - but better to try the easy stuff first.

Also, how do you know it's running rich? What colour are the spark plugs after a run?

G


You can smell the fuel and the previous owner and mechanic both confirmed that the problem is that it's running rich. I literally have no idea how to wind the jets back up or how to check the plugs but I'll read up on that and give it a shot. This is the first car I've owned a long, long time so I have a lot of learning to do.

#4 mossy

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Posted 14 November 2012 - 08:57 PM

I thought you were taking it to Daniel at DJM?

#5 Herbonius

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Posted 14 November 2012 - 09:08 PM

I thought you were taking it to Daniel at DJM?


I am. Have an appointment with him tomorrow. He hasn't even opened the bonnet though he said to just switch to 240Z carbs and forget about it. That'll cost me $1000 and I don't want to spend that unless I absolutely have to.

#6 Gyra

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Posted 14 November 2012 - 09:14 PM

What side of town are you on? I'd be happy to take a look if you want.
$1000 sounds expensive just to change over to 240 carbs!
(Then again, it can be fiddly, and time is money)

G

#7 Herbonius

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Posted 14 November 2012 - 09:25 PM

What side of town are you on? I'd be happy to take a look if you want.
$1000 sounds expensive just to change over to 240 carbs!
(Then again, it can be fiddly, and time is money)

G


$1000 including parts is what I've been quoted. I'm in Hawthorn.  I'll have crack at it tomorrow. If I don't get anywhere it would have been great if you could have a look but you are a bit far. Thanks for the offer though!

#8 MaygZ

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Posted 14 November 2012 - 09:32 PM

Watch these:







They will show you not only how to tune SU's but show you how they work.  really worth watching.

#9 Herbonius

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Posted 14 November 2012 - 11:42 PM

Watch these:







They will show you not only how to tune SU's but show you how they work.  really worth watching.


Excellent stuff to get me started here. Thank you.

#10 Herbonius

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Posted 15 November 2012 - 11:06 AM

Daniel had a look at the car for me again today and is sorting it out. Seems to be running so rich at low RPM because of the cam and the carbs. He tuned it a little though and it will probably pass RWC now but I will switch to 240Z carbies ASAP. Very knowledgable guy. Thanks for the advice everyone.

#11 silverz

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Posted 15 November 2012 - 11:57 AM

Hi,
I watched your youtube clip. It is a beautiful car,  congratulations.
I may be off the track but just wanted to offer my 2c worth before you go and spend a lot of money.
From what I could see on the youtube clip your car did not seem to run that badly to me. Remembering the motor was cold etc, however obviously I wasn't there to smell/see the fumes , remember though fumes in the cabin is a noted problem with these cars.
For what it is worth no matter how hard I try to tune it  my 240Z always idles a little bit rich, however runs well and gets reasonable fuel consumption, so can't be too bad.
I did not know much about these cars initially (and still have an awful lot to learn)  but have managed to learn how to tune it to run reasonably. With patience and using all resources available such as workshop manuals and info from the great resource that is this website you should be able to pick it up.
I don't know anything about 260Z flat top carbies however speaking to Pauly (another member here) when he kindly helped me with changing the head on my car recently he told me his 260Z went really well with them when he first got it, so maybe when they are worth having if they are in good nick.

The main point I would like to make is when tuning the car, do everything else first, check the ignition timing, condition of the plugs and points (if it still has points) and make sure the air cleaner element is in good nick etc before you do anything to the carbies.
You may find you do not need to totally replace the carbies at all (seems a bit of an extreme first measure to me). They may just need to be set up correctly with the float levels reset etc.

Regards
Peter



#12 luvemfast

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Posted 15 November 2012 - 12:49 PM

I've never heard of a car failing a RWC because the carbs were running rich  ???
Daniel seems to know his stuff. But don't spend unnecessary money!


#13 silverz

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Posted 15 November 2012 - 01:32 PM

Sorry,
You posted that Daniel had a look at your car while I was still writing my post (interupted by a friend). If an expert says the carbs need replacing then I would take his advice.
Regards
Peter

#14 Herbonius

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Posted 15 November 2012 - 02:16 PM

Sorry,
You posted that Daniel had a look at your car while I was still writing my post (interupted by a friend). If an expert says the carbs need replacing then I would take his advice.
Regards
Peter


No, thank you for the advice! Good to hear multiple opinions on this stuff while I'm still learning!

I've never heard of a car failing a RWC because the carbs were running rich  ???


It was more about emissions. As it was, it would have clearly failed any emissions tests. It's running OK now though. Thank you!

#15 welfares

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Posted 22 September 2015 - 03:56 PM

I've got a 76 260z with the flat top carbs.

 

It was running rich an gradually getting worse to the point where it ran like a bag of ...... coughing and spluttering anywhere in the mid range.

 

Idled rough, but went ok flat to the boards.

 

A bit of investigation let to me putting a blank gasket on the accelertation valve on the offending carbie.  Its a round bit on the side, about 30mm in diameter with 3 screws holding it on.

 

Problem solved.  Fixed the spluttering and got normal fuel economy again.

 

I'm not sure if it affected the acceleration, I use it more as a grand tourer but it still gets up and goes fine, so if it did it's not much.






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