su Is Walker 15566 the correct carb rebuild kit? YES!

[jonathanrussell]

Here are some measurements for you. I opened up my 72 3 screw carb set from my 24k mile 240z I am refreshing. I don't think these carbs have ever been touched. They even have the original needle jets.

Anyway, the front carb has the caps with the longer ears. The length of the front cap ears from cap to the end of the ear is approximately 18.1mm or .7125 inches. The length of the front cap ears from the cap to the approximate center of the pin hole is 14.15mm or 55.70 in.

The rear carb has the cap with the shorter ears (same as what your 4 screw carbs should and do have both front and back). The length of the rear cap ears from cap to end of the ear is approximately 12.78mm or .5035 inches (consistent with what you measured). The length of the rear cap ears from the cap to the approximate center of the pin hole is 8.52mm or .3355 inches.

 

So here is what I think and others can weigh in as to whether I am understanding correctly. You have 4 screw carbs that have the correct float bowl lids with the short ears (or towers) both front and back. The problem is, someone installed a needle jet kit at some point that is for a 72 carb setup so your rear carb has a long needle jet and a short ear lid....which will / should never work. I think that if you install two short needle jets and set the float levels you should be in business.

Wells makes rebuild kits and they sell short or long needle jets. If my notes are correct, CK749 is the short needle jet kit. You could also just order needle jets from ZT because I think all they sell is short.

If I remember and understand what you wrote above you are struggling to install a short needle jet on the rear carb. What the prior owner probably did is severely bend the adjustment tab to force accommodate the long needle jet. So, you may need to do some tab reshaping. Use your front carb cap tab as a guide.

 

Hope this helps.

 

[Patcon]

Just remember even fresh Ztherapy carbs need some tuning to be right. they come pre adjusted but sometimes they need to be tinkered with.

[DannDZ]

4 hours ago, jonathanrussell said:

If I remember and understand what you wrote above you are struggling to install a short needle jet on the rear carb. What the prior owner probably did is severely bend the adjustment tab to force accommodate the long needle jet. So, you may need to do some tab reshaping. Use your front carb cap tab as a guide.

So should the tab be above the "armature?" By armature I mean the body of the pressed metal tab and by above I mean closer to the lid. It was above when I took it out, but in my attempts to set it correctly, I pulled it down substantially and below the rest of the tab.

My measurements and comments about the length of the nozzle was not very clear. I am not very good with "fancy" measuring tools. So I took out a good ol' metal ruler and alighned everything. It gives you a much better picture of the difference between the two nozzles.

Thanks again for you help,

-Dann

[DannDZ]

7 minutes ago, Patcon said:

Just remember even fresh Ztherapy carbs need some tuning to be right. they come pre adjusted but sometimes they need to be tinkered with.

I'm sure they do. I have to tools to tweak them as needed. These were just very difficult to adjust to begin with. The biggest problem was that I could not get the body nozzle to level with the bridge on the front carb. I simply could not turn the adjusting screw up high enough. So we removed the carbs to take a look. It was never my intent to attempt a rebuild. I found the reason for the initial problem, some bent washers were preventing the full range of adjustment. But, since I had them off.... Probably should have left well enough alone and reinstalled them at that time!

My expectation is that if I get the right kit, especially from ZT, I can probably get it together. OTOH, the car is 49 years old and treating it to a professional rebuild may be the thing to do.

-Dann

[jonathanrussell]

1 hour ago, DannDZ said:

So should the tab be above the "armature?" By armature I mean the body of the pressed metal tab and by above I mean closer to the lid. It was above when I took it out, but in my attempts to set it correctly, I pulled it down substantially and below the rest of the tab.

So, the drawing below shows you how the tab should sit in relation to the metal float arm that attaches to the float cap ears. With the orientation shown in the photo it curves a bit above the parallel line of the top of the float. In the drawing, if a long needle jet were installed, either the tab would be drastically bent down OR the float arm would be bent and the travel possible for the float would be severely limited.

Also, regarding your measurements. I can tell that your short needle jet is about 1" which is about the same measurement I am getting in MM...what I wrote above- 25.25mm.

I agree with what Patcon said. ZT carbs come to you in great shape and I would say decently adjusted. The carbs I have received though (two sets) have benefited from more careful adjustment of the float levels. Don't get me wrong though...they do awesome work.

Hope this makes sense and helps.

 

[DannDZ]

11 hours ago, jonathanrussell said:

the drawing below shows you how the tab should sit in relation to the metal float arm

Yes, that is the tab I am referring to. I think I need to do some more research into setting the float level. I'm calling ZT today. Still trying to determine if I want to "spend big" and have them do it as right as can be done off the car, or attempt to do it myself with their kit.

[madkaw]

I remember - vaguely- when I had a similar situation . It was something about the long jet assembly was no longer available but I had a carb with the longer ears . I believe I just redrilled the ears to the proper height to match the pivot point of the shorter jet assembly! So I just moved the holes up for the pin and adjust 

[jonathanrussell]

Both of his caps have the short ears and thus need the short, easily available, needle jets.

FYI, the long ones are available from a company named Wells. I think I purchased from Rockauto.

For those who have long ears though...I actually like madkaw's method....re-drill and use the shorter needle jets...OR locate a short ear bowl cap and replace. I just don't like how the long ear / long needle jet config works in the bowls.

I checked Rockauto. I am not seeing the same options I was able to order a year or two ago. But, the kits I ordered at the time were similar to this offering on ebay (see below) where the kit is for one carburetor but it includes two needle/seat bodies...one short and one long. You assemble the one you need.

https://www.ebay.com/itm/Carburetor-Repair-Kit-For-1972-Nissan-240Z-C158SV/173967875276?hash=item28814b1ccc&_trkparms=ispr%3D1&enc=AQAEAAADIKvsXIZtBqdkfsZsMtzFbFsbX3WcW5fmB%2Fx7ZbaZTyex8i7n1lQ38Wwv00fEvu8N9rCKQfFKON4NOQ3D8SmHNmA9jykbbq7wo13Cux%2BQpQ3L3ZF3gVbgO8vQKDrboxJ1C0IL4WhifbrVuv%2BruWod44VIrGRv0W8Y3jhtVPUlLpPcPJ8Mt3spoLlpiG7pEojg0tsI5QlxVSZAbdj6nX8aWti2H5zgmCzjZdfpI%2FvtdnTddUi8QHBH%2FCN847fCCi0C7dp1gldpOZFzndtTPHwHwqkQWLU9M3NnyRmNXuFiR9JDYvB0s%2FtUZnXwqTVUQAkILFugvcotpy455CcSX8qQUqBTtKIycchyAFPPOdX5WGwx3bt53OE9IOrX2QmbxujOoxs2HSSfUza7M%2BcNa5CgWfvyIatuLAv7fVy2Ss2jVIKAZ%2FglxKDQczdFSGy4Rlm1vSZVZ3%2Fvze%2FllamSoXKYwCF55BEqng977c6wt5x2%2B%2BFPkQ%2FGTH0nJhNO0u6gx%2B6vt%2BYZ4rwai6oaOYtPOTfdIh1IKeVFNobeM%2FpL8ub4SOpA9MfKsW%2BKzeHcT35APm5GBWp9%2BwaOKZ5suqp6807VdPtbMj8h24Fgf0QCJ7VdSnz5t1%2FCPU7QgoC9XackNd2Fn606d6qwqInQsH7xXkCXCPaMfgmU9XUVVixkCarpdO99N9SQSvR8YX6JUPyIXjuTV4QV6Oi5QK3BZ4zMv4mw031u6lRl7p6yogLknt8RCmdCmktQOPTG7XAM0%2FbLROPDSE1%2BJgJE%2FEi45FCQe2N5gbFm2Zxs1GAepj2rtNjaz87ucRlh7hrhrQn%2Bu14r53qb1IyfRCgWcukjEzfKyP4Bqvtl4YGinjBVrOKrTz%2Fc7%2BrmkcyZUp%2BU%2BnNMKuz1JsVao2fVBzI1lzqBElXPWM7y7F9F8mY47se362zX6W99XvqQn8NHnsa5eGOI3Or4ZcbJO4z2A4xGlk2NBL8XFAC%2FK%2B3q0RTu9v3icCbPNRMS6xASFQjK1va57IeVyjMybxyVAwHnEWYlkREG2vElt6C8CukkpTDLC%2BQSqPqJWnqplAnp&checksum=173967875276bd133e6b6a8147c0a38f7c54e304c2c3

 

Edited October 11, 2019 by jonathanrussell
additional info

[siteunseen]

Check your float tang too.  You don't want them bent up like ramps.  They need to look like speed bumps.  Here's a thread that has some good photos.

Click on "siteunseen replied to a topic"

 

[DannDZ]

6 hours ago, siteunseen said:

Check your float tang too.  You don't want them bent up like ramps. 

Excellent insight. In fact, I talked with Bruce at ZTherapy today and he made the same point. 

The link is particularly helpful. I think it takes a bit of an artist to make a smooth curve like that. But one thing Bruce was clear about is that this is not rocket science.

[DannDZ]

On 10/10/2019 at 1:21 PM, jonathanrussell said:

Your car year and the fact that you have 4 screw carbs should mean that you have the float bowl lids with the short ears that the pin slides through to hold the pivoting float assembly. You should have short needle jets in both carbs that are 25.25mm long (measuring from end of threads to end of body...(not including the actual needle that moves in and out of the body).

Both carbs are rebuilt and back on the car. It took a bit to get the fuel supply, but it fired up nicely. Of course, much tuning still needed.

You are right about the needle jet lengths. I found that someone had replaced the rear jet with the long jet! The one that came in the Walker kit were right. They were the shorter version and I now have them in both lids.

After a lot of discussion help and trying options, I have to say that the Walker 15566 is the correct carb rebuild kit for my early Z. The gaskets fit and the jets are the right length. I tested three fuel lines. 1) Braided fuel lines were a failure. Too large and inflexible.  2) The set of ZTherapy lines were supple and easy to install. 3) The kit's fuel lines were only slightly stiffer than those from ZTherapy. I recommend that you give them a try.