Zedyone_kenobi

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!

I do not have a suitable plug for the PVC yet but plan to pick one up tomorrow along with a plug for my o2 sensor bung. I will try the choke tomorrow but I recollect doing that before with little success but let me confirm for you. No stone left unturned! Have I mentioned you guys rock Getting my o2 sensor hooked up must become top priority. It will remove some of the guessing

Nah, when steve91tt we ran the car at essentially 1 deg BTDC with his distributor and it still did it. It popped when I ran it at 10 deg, 14, deg and 17 degrees, and it fully advanced by 3100 rpm or so. I got my Innovative LC-1 wideband in today. I just need to wire it up and get my exhuast drilled for the metal cupling. I was hoping it would have come with a plug AND a sensor. But it only came with a sensor. I wanted to get it installed with the cap on, then come home and install the sensor. Now I will have to do it a bit backwards. Wire the computer up and install the gage, and then drive to a muffler shop to get the bung welded on and a hold drilled.

I changed out my fuel filter same thing happens. Nothing of note. Should also note my last chance filters in the SU's were very clean as well when I looked at the float bowls I put a vacuum gage on the manifold vacuum going to the power brakes. After the engine is warmed up, it pulls 19-20 psi pretty steady at 750 rpm. NOTE: I checked out my exhaust slip flanges from where my 6-2-1 header goes from 6 to 2. They were a few turns loose each. The one that goes from 2 to 1 I could not get to without jacking up the car.

That is VERY generous of you Steve! But I cannot do that to your daily driver. I would never ask you to. Not yet anyway ! HA HA. I would rather just buy the mikunis and webers and have those as a back up to my SU's, or have my SU's as a back up to the triples. I wish I had an easy answer to what this was. We have picked the low hanging fruit. Now it is time to find the more obscure things that have a drastic effect. Things like the vacuum leak come to mind. When I go more than 3 turns out the car just stumbles and dies when it tries to idle. Perhaps I should try to open up the flappers a bit more to keep her running. A wideband will tell me how lean or rich I am at idle so that should provide some insight to that issue.

I have spent some time thinking of this actually Captain. The answer varies so wildly with the results. I do not forsee the wideband being so cut and dry. I hope it does, but in reality we both know that it will be XXX at idle, and YYYY at 2500 rpm, then ZZZZ when it is popping. I am hoping to see a trend. If I know I am leaning out, then I can try to find out where in the fuel delivery I am leaning out. Is my fuel pump providing enough fuel, is the float level adjustment right. Is unmetered air entering into the system. If I know I am rich, then the list gets easier. Try to find out where the extra fuel is coming from. the thing is, all it does is put me into the right ballpark, and gives another data point to help diverge ideas from one another. It also is a quantifiable piece of data which directly relates to the engines running. My thought is that I should not be running rich here and lean there too much. My car is stock except for the header and the custom curved dizzy. Head, cam, block, etc is all stock. Stock SU's should be able to compensate for any small variances between my setup and a totally stock setup. Perhaps my engine is not totally healthy, although that would surprise me. Maybe my cam is not totally up to snuff, but that would surprise me as well. Your question is one of great importance...and one I shall have to deal with eventually.

I cannot go more than 3 turns out as the car will not run anymore. It stumbles so badly it barely runs... I took off the PCV and blew into it from both sides... only could blow through it in one direction I will cap it though and go for a drive..

With the float hung upside down, I picked up the float and the instant it touched the needle with the tang, I took the measurement. It was about .55" as per the factory manual. This differs from the SU video as he showed the float top parallel with the float bowl cover when held upside down. Maybe I should ask Bruce for an explanation of this.

I currently run 17 degrees BTDC per the european spec dizzy I had mine recurved to match. I do not run a Vacuum Advance. I have made the runs with the BARE SU;s with no air cleaner (just plain easier to adjust quickly), with the air cleaner base on but no filter or housing (to get the benefit of the air horns), and with the air cleaner. NO noticeable difference either way. Get popping from the exhaust in all part throttle situations near 4000 rpm. I just do not see it being a fuel delivery problem when I will run at WOT, but not part throttle

I have 2 extra fuel filters lying around. I will put one on when I get home today before I check out my car for vacuum leaks. Cant hurt.

again, webers or mikunis haha