Zedyone_kenobi

Carbs are like personalities. If treated properly, they are happy and easy going, more than delighted to perform. But when neglected they can cause all manner of weirdness. Sometimes, even when you think you are treating them well, they get all foul tempered... ask me how I know.

Those wheels are uber sexy.. nice job..and you are just feeling my crack like obsession I have now with Weber carbs

If you think it is your tach, run a jumper from your 12v source to your + coil terminal and unplug your tach. This takes the tach out of the loop. Did not work for me but good luck

O2 sensor bung installed. now to wire up my Innovative sensor and we can start to get some readings!

Understand completely. Like any data you have to know its limitations.

A glimmer of HOPE>>> I put my carbs back together (SM needles back in) with the only difference being that I put in some 10w-30, and she ran VERY well this morning. I was able to push her at part throttle easily to 4500 rpm, without the slightest hint of a pop. When I pushed it past that, I got some minor pops, but 10w30 did make an appreciable difference. I am taking her in to the mufler shop today to get the O2 sensor bung welded on and I will finally know where I am running. I am also going to do a full test on my brake booster check valve tonight. I will report back later... Having good O2 readings will be very informative and hopefully helpful.

LOve the car and the color. So that is what my silver Z would look like with no bumperettes on it the front. Interesting.. (scratches chin!)

I think the key to this is not to get stumped. I feel like my car is a patient on HOUSE, Some crazy ailment that I have to try half a dozen things to fix before some obscure thing triggers a eureka moment! Still I cannot thank everybody enough for their time and energy replying to my dissertation of a post!

The one for noise suppression at the coil is in fact removed. I will check to see if the one for the points has been removed, since I am running a pertronix.

NO we actually switched the entire cap / rotor / dizzy as a whole unit. I had already tried a new cap and rotor a while back. I did as much common sense trouble shooting as I possibly could in the past few weeks before I started this thread in frustration. I am winding down to the last few ideas that I can possibly use on the carbs. I have checked every measurement possible. The kicker is the part throttle nature of it all. What would cause this issue at part throttle but not at WIDE OPEN THROTTLE. The PCV and brake booster were not leaking. I thought maybe worn throttle shafts that at part throttle that allowed a leak (unmetered air) into the system at half throttle, but not at WOT. But the bearings Z therapy puts in should have eliminated that as a possibility. I need to get on the ball with the O2 sensor and stop messing around chasing my tail.

Cant help but report results... plugged the PCV and the booster out of the manifold, same issues. If it is a vacuum leak it is from somewhere else. All bolts are torqued. I did put back in the SM needles and while I did that I cranked down the fuel mixture as far as I could...about .205 inches until it hit the stoppers. I had the domes and pistons out and the fuel was definitely below that... as it should be. But how far below, not sure until I can get the stoppers out to use 30 Ounces technique. While I was at it, I put 10w30 per the FSM recommendations in the carbs. Will drive it when the rain clears up. If that does not pan out, then I will declare victory over the carbs and start measuring how much slop is in my mechanical drive that spins my dizzy. Oh after I get my O2 gage set up. I will probably pull the valve cover off Monday just to have a look around. Sorry to keep this going,

You guys have been a huge help! I mean huge. I cannot thank you enough. I am going to stop posting results for a while and get my O2 sensor installed. I think my post has generated a little discontent from somebody whom I respect immensely in the Z community. I am going to get out my FSM and trouble shoot this as completely as I can before I bug the good gurus here. I thought I had done that before I posted the first time, but just to be sure, I am going to triple check. Again, steve911 madkaw blue doradox Captain Obvious 5thhorseman Diseazd 30 Ounce and anybody else I have missed And anybody else I may have missed. YOu guys are all 1st class. Always have been. I am going to stop hogging the resources of this board until I have something worth while to report.

Guess I should feel dumb

Okay, lots of help here, let me address everything I can. MY distributor was rebuilt by Advance Distributors, who put all new bushings, seals, and ensured that there was no slop in the timing up to 8000 rpm. The guys is very well respected from what I read from MG and other Datsun guys. I trust his work. With my light on the distributor, it was rock solid up to as high as I would want to rev it. Now I have NO idea how solid my oil pump is, OR my crank gears, etc. I am going to pull all the domes again, and try some straight 30 wt per recommendations, as one last ditch for the carbs. I will put the SM needles back in while I am doing that. Then I am going to plug the brake booster (which I just replaced with a new one this year) and drive it and then plug the PCV and drive it. I finally got a plug for it. After that, I will pull the valve cover and have a look at what is going on there. Blue, I did not mean to try to confuse or 'cry wolf'. I am keeping track of a huge amount of data and I do at times forget to report in so to speak. When I first got the car it did in fact NOT rev at all past 4500 rpm, at part throttle, full throttle whatever. A new cap and rotor and actually timing it to 5 degrees BTDC like the factor recommends fixed that. To the degree this problem may have always existed is tough, as for the first 2 years, I really did not push the car super hard, so it may have always been there. What I am glad to see is even and high compression numbers on my car. I do not know how many PSI it should have stock. I ran another compression test on it with the butterfly open and it came up to 182 +\- 2 psi on all the cylinders. It is possible I have a bad brake booster, or a leak somewhere that only arrises under load. But the brakes work splendidly. I have to admit, this has all the symptoms of a vacuum leak. Again, I am sorry for any confusing info... The cap and rotor did let me rev beyond the 4500 rpm wall for the first time, that is true, but the Ztherapy carbs allowed me to run powerfully above 4500 rpm for the first time. But blue, you may actually be 100% correct in the end.

Well I took her out for a spin and to no surprise the float adjustment did not fix anything, BUT I can definitely rule out the floats not being adjusted... So while the engine was warm, I took the plugs out and looked at them and then decided to do a compression test. I taped up the pistons in the domes, but like a dummy I forgot to push the accelerator to the floor while I cranked the engine so the butterflies would be open. Still, these are my results 1 2 3 4 5 6 175 175 172 178 175 178 FAr better than I thought. Those numbers were with 5 compression cycles. I also did some runs pulling the choke when it was making a popping....This is what happened. I was in second gear and slowly gave it gas until I was into the severe popping regime. Then I pulled the choke back a bit where I knew the jet tube was being moved down. The car surged forward and started to accelerate again, but started popping again at almost 6000. The car seemed to like the enrichment. This led me to think the car was running lean despite the popping noises it is making... so I pulled the plugs after driving home normally.. Here are the results.

Only occurs when I am actually driving, sitting still and revving it is perfect

They have no numbers on them, I looked. But the invoice from Z therapy said N27 I am 99% sure. I will check for you and get back. I agree about the low float bowl having little to do with part throttle popping, but I have to check everything at this point... I will figure this out if I have to replace every single part on this car one at a time. If that means building up an entirely new L24 so be it, but as GOD as my witness I will track this down!

I managed to get outside and check the float bowl levels using the clear hose trick mentioned by the wonderful folks of this board. I marked the outside of the fuel bowl .906" down from the fuel bowl rim (I know technically it is supposed to be measured from the inside lid, but it is close enough to see if I was off. The front bowl was just about right up to that mark I made, not quite but close. The rear bowl was about a 1/4 to a half inch below that mark. I cranked the car for a good 8 seconds each time to give the bowls plenty of time to fill up. So I removed the rear bowl and bent the little tang the slightest bit toward the float. I reinstalled it and presto, dead even with the line. I have not had a chance to drive it yet, as tonight is date night with Mrs. Zedyone, but tomorrow morning, I will take that baby for a spin. I cannot find a shop to weld in my O2 sensor on a saturday, so I am stuck waiting a bit longer to get that working. But I will report back after my drive!

Way to go man! Keep her alive and strong... Makes me feel good about working on my car!

Going to check out the float levels tomorrow when I hopefully get my O2 sensor bung welded in!

Pics or I will throw poo at you!

Maybe I should get data and not assume anything... At NASA here in the cryogenic propulsion division, we have a saying... 'In God we trust, all others bring data....'

I just feel bad about asking him to take his carbs off his daily driver. I know it is just 8 bolts, but still. I will do that before I do anything drastic I promise. first I need to get my fuel level in my carbs verified beyond a shadow of a doubt. As far as air leaking on the throttle shaft, I have to believe that Ztherapy carbs with their patented seals and bearings have eliminated this as a possibility... But a carb swap would be an easy way to verify this...

This is something I think I need to do. How many times can I reuse the stock cork SU fuel bowl gaskets? I was going to try the clear fuel hose trick this evening if I could. I probably will not be able to get the O2 sensor installed for a week. Just too busy. I have not verified my fuel level in my float bowls, but by God I will soon!

Nope, but I intend to. I will get a bottle of SAE straight 30 wt to give it a try. I am sort of on hold until after I get my O2 sensor in. My time is very limited each day, and I try to squeeze as many ideas you guys give me as I can. But windows are small. I will make every effort to go for a drive to day to try the choke thing again. I just do not remember the results. I will also try today to block off the PCV and see what happens. I am going to order more SU float bowl gaskets and try to get an actual visual reading on that float level with a straight edge and a piece of clear tubing. While I do that I am going to put the SM needles back in. You guys are worth your weight in SU oil let me tell you!