My eyes! Pig rich 260Z - adjustments?

[Ron Earp]

I've got a 260ITS z car in my garage that needs some TLC. Whilst working on it I figured, hey, I'll fire it up and adjust that horribly high idle down a bit.

Well, it fires up well, runs smooth and sounds great. But while running at 2200 RPM, where it happens to idle, I can barely breathe near the engine compartment and it is so rich my eyes burn something fierce!

So, not being familar with these carbs, that is I understand the basic ops of carbs but not these, how does one affect the mixtures on these guys? Is there an idle mixture screw? Raise and lower the needle (I'd expect this for mid-high RPM ops)?

The car has exhaust gas temp probes in cylinders 1 and 6, although I've not really tried to collect data from them or notice what they run. I can do so though since that should give us an idea later on tuning, but right now I know it is rich!!!O

Oh, fuel pressure looks good and constant at 3psi.

Thanks for the help,
Ron

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Ron Earp
http://www.gt40s.com
Ford Lightning
RF GT40 Replica
Jensen-Healey ITS
My electrons don't care if they flow through OEM wires, do yours?

[This message has been edited by rlearp (edited January 27, 2005).]

[Joe Harlan]

Ron, The 260 had the worst carbs of all on it but they can be made to work. I assume this is a race car?

You have 1 idle screw on the manifold and each carb has a screw. The mixture adjustment is on the bottom of each car. You need to turn them up equal amount to lean the mixture. Have you ever balanced dual carbs before?

[Tom Donnelly]

I'll probably catch hell for this but...

Send them out to ztherapy (www.ztherapy.com).
$500 bucks but you'll really like what you get back.

Joe is right about the 260 carbs. Yuck. But he is also right about the mixture screws. You also need to check the needle and seat for wear or trash, check the oil level in the piston (use a real lightweight oil) and get katman to espouse the wonders of z carbs. He knows quite a bit about them. Joe knows from British stuff so you have quite a knowledge base here.

Joe,
Whats with ground hog day? I still don't get it concerning MGB's in FP. You mean "the same storey over and over and over and over.....


Tom
ITS 240z

[Ron Earp]

Yep, ITS car, purchased not long ago and it is the one that was listed in the classifieds here. Long race history, since 1992, and has some pretty good placements at notable tracks.

I'll check the screws out. I've balanced multi carb system, motorcycles with four and SB Fords with 4 webers, 8 barrels, so that isn't the hard part. The hard part is learning a new carb and how it responds to various things. I've got twin Strombergs(yuk) on the Jensen so this is not uncharted territory, just uncharted from that standpoint of Z stuff.

I'll report back what happens, thanks much,

Ron

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Ron Earp
http://www.gt40s.com
Ford Lightning
RF GT40 Replica
Jensen-Healey ITS
My electrons don't care if they flow through OEM wires, do yours?

[Ron Earp]

Yep, ITS car, purchased not long ago and it is the one that was listed in the classifieds here. Long race history, since 1992, and has some pretty good placements at notable tracks.

I'll check the screws out. I've balanced multi carb system, motorcycles with four and SB Fords with 4 webers, 8 barrels, so that isn't the hard part. The hard part is learning a new carb and how it responds to various things. I've got twin Strombergs(yuk) on the Jensen so this is not uncharted territory, just uncharted from that standpoint of Z stuff.

I'll report back what happens, thanks much,

Ron

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Ron Earp
http://www.gt40s.com
Ford Lightning
RF GT40 Replica
Jensen-Healey ITS
My electrons don't care if they flow through OEM wires, do yours?

[Joe Harlan]

<font face=\"Verdana, Arial\" size=\"2\">Joe knows from British stuff so you have quite a knowledge base here.</font>

What? I have done a bit of british stuff but I build some of the fastest Nissan engines out here. I am just choosey about who I do them for....lol

As far as ground hog day goes. Your right same BS from the same guy so many times I just thought a movie title was the best answer. Next it will be the scarlett letter....You know the letter L

Ron, If you need a copy from the factory book on adjustment proceedures e-mail me direct and I will scan it from a book.

Joe

[Joe Harlan]

<font face=\"Verdana, Arial\" size=\"2\">Joe knows from British stuff so you have quite a knowledge base here.</font>

What? I have done a bit of british stuff but I build some of the fastest Nissan engines out here. I am just choosey about who I do them for....lol

As far as ground hog day goes. Your right same BS from the same guy so many times I just thought a movie title was the best answer. Next it will be the scarlett letter....You know the letter L

Ron, If you need a copy from the factory book on adjustment proceedures e-mail me direct and I will scan it from a book.

Joe

[Tom Donnelly]

Sorry Joe, I thought you were mostly British. As for groundhog day, the first thing I think of is Andie MacDowell, she's beautiful, she's my age and she has a southern accent too.

Tom

[Joe Harlan]

Andie........need i say more...

[lateapex911]

I hear Aniston is newly single.....and that she likes a guy who's good with his carbs....

Although it's probably carboHYdrates, not carbURetors...oh well, nevermind!

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Jake Gulick
CarriageHouse Motorsports
ITA 57 RX-7
New England Region
[email protected]

[Ron Earp]

Hey Joe,

Can you write a quick layman's description here?

I have the shop manual and it indicates monitoring CO to set the idle adjustment. Is there anything like "screw it all the way in and back it out 2.5 turns", or something similar. I'm sure the idle is messed up - waaaaaaaaaaaaaaay rich. Not sure about part throttle or WOT, one step at a time.

It does have exhaust gas temp probes in cylinders 1 and 6. Got a rough idea for what a good exhaust gas temp is for good running? I think it is #6, or second carb, that is so rich - #6 reads a temp serveral hundred degrees less than #1, unless the gauge is busted.

Thanks,
Ron

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Ron Earp
http://www.gt40s.com
Ford Lightning
RF GT40 Replica
Jensen-Healey ITS
My electrons don't care if they flow through OEM wires, do yours?

[SpudZ]

Ron,
I looked at the photos when the car was for sale , but I think they were taken down . Does the car have the choke cables removed ????

Make sure that they are totally removed and if my memory is right the arm is down , so that extra fule is getting in there .

I had those on my street 260 and the engine ran fine with them , but as you can tell Nissan did what ever they could to get the
cars through smog until the injection was ready

Also you might check to see if the floats are
still floating

Mike

[SpudZ]

Whats the ruling on the use of the round tops in ITS ?? The rules just show Hitachi SU's for the 260 , and don't say anything about the flat top carbs.

The flat tops were used on the 240 as well from June of 72 on . Most owners switched them out as fast as they could .

Mike

[This message has been edited by SpudZ (edited January 31, 2005).]

[HounDawg]

Originally posted by SpudZ:
[B]Whats the ruling on the use of the round tops in ITS ?? The rules just show Hitachi SU's for the 260 , and don't say anything about the flat top carbs.

One word: illegal.
I have fiddled around with the flat top 260 carbs, too and finally gave up. They just weren't designed to allow adjustment. Maybe ZTherapy can do something with them, though. Not that I'm any genius, but I ran a 260Z in Solo I (and a few road racing attempts). Just to see what they would do, I put a pair of round tops on the 260 and the difference was unbelieveable! My lap times at Charlotte dropped by 12 seconds! Still, even with optimally-functioning flat-tops, my opinion is that the 260Z is too heavy and its longer stroke inhibits higher RPMs. That's why I've retired the 260 and am slowly but surely moving forward with building a 240. Good luck, though, with your 260. I'll wave as I pass!

[Ron Earp]

Thing is, this 260z was already built and has a long race history with some finishes in the top five in the 90s against some impressive machines - Chet Whittle's Z is in some of them at position number 1 and the 260z times are a couple seconds off. don't know about the driver. Yes, 2 seconds is a lot, but still not as bad as I would have thought.

It also has some dyno sheets with it and the numbers are pretty good.

I've checked with Z Therapy and have some leads - there are at least two people that know how to make 260z carbs run and I'm trying to get in contact with them. Z Therapy doesn't do anything with them though.

I'll run this joker in on a chassis dyno next week and let you know how it looks.

Also have some UK leads from my GT40s.com forum - seems the Z's in the UK always got flat tops and they can make them run. Got one member who has a 260z that runs well and has offered to help out.

Ron

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Ron Earp
http://www.gt40s.com
Ford Lightning
RF GT40 Replica
Jensen-Healey ITS
My electrons don't care if they flow through OEM wires, do yours?

[Joe Harlan]

Ron, I would stick with your plan I will try to sit down this evening and give you a basic run down. I would also request of the CRB to use the early carb as an alternate. Those carbs were made very poorly and were emmissions only type crap. I believe than can be made to work at great expense in testing. Now since a single carbed car get to run an alternate I don't think asking for a proper alternate for your car would be completely out of the question. If you would like help with the request let me know I have a 260 owner out here that maybe interested also.

[Ron Earp]

Hi Joe, I'm off to California for 2 days so no hurry, but I appreciate the help and will look forward to the run down.

I would like to try and get an alternate carb. I don't know why they would refuse it, I mean, it has a weight plenalty for the extra displacement, but the carbs are rotten. If you've someone interested then let's get together and write a letter - I don't know how so will need help.

I don't know why they should refuse - if it gets more cars in IT that is a good thing and there are a lot of 260z running around. In fact, I know of one person with a 260z that would run his I think instead of ditching it.

Do you sell Z parts, like the brakes?

Ron

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Ron Earp
http://www.gt40s.com
Ford Lightning
RF GT40 Replica
Jensen-Healey ITS
My electrons don't care if they flow through OEM wires, do yours?

[Tom Donnelly]

Ron,
www.zhome.com has some information on tuning z carbs. And some dyno sheet from katman. And ztherapy has a how-to video. And there's Joe.

Try all of them.

Tom

[Joe Harlan]

Yes, I sell parts and I am happy to help I just don't come here to pimp the stuff...

I have Hawk pads nismo shoes Brembo brake drums and maybe rotors for that car.

Let me know if I can help. I will take a crack at the request for carbs and send you a copy.

[Ron Earp]

Hi Joe, shoot me an email at [email protected], I do need some pads as spares and should get good ones. Thanks for any help on the carbs, Ron

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Ron Earp
http://www.gt40s.com
Ford Lightning
RF GT40 Replica
Jensen-Healey ITS
My electrons don't care if they flow through OEM wires, do yours?