Zedyone_kenobi

And I whole heartedly swear to all of you who have been with me here for 16 pages that I SINCERELY APPRECIATE ALL OF YOUR HELP! I HAVE NEVER met a bunch of people on an automotive forum as classy as friendly and helpful as you all have been with me. I am truly blessed to have discovered this forum. I consider myself a pretty handy wrench. I really do understand the workings of engines for the most part. I have my areas where I am weak on, but for the most part, I get what everybody here is trying to help me with. But Captain, no offense, while I appreciate the advice, the 'experiments' have been going on for almost a year now, 4 months of it was in this THREAD! I am ready to change the game up a bit. I am still going to attack the problem, because I never quit. But instead of the surgical strikes I have been performing, I am going to go more with carpet bombing from a B-52. I will keep reporting back to you with what I find with my leak down test. If I had another set of SU's I would try them. If I had a points dizzy on hand I would probably try it. But I do not.

I think I am at a point were I want to pull the cylinder head off. I may do that today after I attempt a leak down test. I finally got a new compressor.

Well sort of. I Use the NGK BPR6ES that is listed on here, both the regular type (NGK BP6ES) and the resistor type (NGK BPR6ES). I have tried both of those at .035 and .045 gaps. I set my static timing at whatever I am going to run, depending on which distributor I have in the car at the time. One of them likes 11 deg BTDC initial, the other likes 17 deg BTDC. Then I slowly raise the rpm until the timing mark stops moving on the balancer. Then I use the lights adjustment buttons to see the rpm AND the advance at that point. Last time I did that I was fully advanced at 3100 rpm with 35 deg total advance. Yes, the vacuum advance was plugged.

I agree 100% with you on the cold adjustment, I may do mine again tomorrow stone cold, so at least I know they are even!

Thats easy for you to say!!!! You can scratch valve adjustment off the list. I really hate trying to do them hot. I would rather take my time and do them cold. NO difference by the way... poppety pop pop I repeated the carb spray test as well. Nothing. What is the best way to ground the block. I was thinking the bolt that holds the tranny to the block, and then hook that up to the firewall.

WEll I agree Beerman, but how many of us on here are running headers on a stock L24 with absolutely zero issues what so ever. On many cars I have worked on installing headers (many SBC) was a great power adder by itself. Yes, you could get more from rejetting, but it was not night and day. And certainly NOT the difference between running like crap, and running well. The E31 exhaust is very restrictive (Rebellos words) and the stock manifold is darn near as good as a header. Nobody is making crazy power with just a header on an L24. I have checked the valves already as well. I checked them warm, not hot or cold. I can certainly check them again. I will also check the block ground, and make some more grounds just for kicks.

Guys what we are facing here, I mean with all the KD needle talk, stiffer springs in the pistons, ignition not being strong enough (which just is NOT possible folks. I have two brand new rock solid rebuilt distributors, with 2 brand new coils, 3 sets of plug wires, 2 sets of NGKs, 3 sets of caps, 2 rotors, and verified my coil is getting 13+ volts all the time. My ignition is solid. It is NOT ignition) is treating a symptom rather than the cause. so this gets back to real issue. All these extreme fixes (aforementioned KD needles, stronger springs, 3.5 turns out, etc) are not what an essentially stock Z should need to run. The only thing I know for sure is my piston rings are in great shape via my compression test. I know my bearings are in good shape as I have completely normal oil pressure I have no insight to the health of my valves, guides, seals, or cam lobes. I truly believe that my problem in the cylinder head somewhere. I would be willing to try another set of SU's if I had some, but I am not about to buy another set from Z therapy. I still want to try to a leak down test of the cylinder to see if I have a burnt valve or head gasket leak somewhere, but I am not sure this would be the case when the car runs PERFECTLY if kept under 4500 rpm and it runs perfectly at WOT. Either way, I am running out of options on this one. Steve, I do not go from 12 to 16 on my AFR instantly. I start at 10:1 at idle and under normal constant speed driving I usually settle at 12:1. If I crack the throttle I go to 13, 14, 15, (still running and pulling fine) 16, then 16.5 and the popping happens. I do not get a single pop until I go higher than 16.5. I have priced a replacement E31 cylinder head from Zcarsource, and it will be 1400 dollars. If I do that, I may as well replace all the timing gear and water pump and oil pump. Add in gaskets and new head bolts and I am getting very close to 1700 dollars. If I am going to do all of that. I may as well pull the whole engine and rebuild it or buy a rebuilt one and rebuild mine at my convenience. I am sorry if I am getting frustrated. I am ready to throw in the towel. My once solid conviction to fix this is getting seriously tested. I have not enjoyed driving my Z in over a year now. It is becoming a VERY good looking symbol of annoyance. Sometimes you just have to start fresh, Rebello? Datsun Spirit? Yes, I am talking THAT fresh.

I tried to find stiffer SU springs Ztherapy said there is only 1 spring used for the Z He did not have any to sell me. I was on the hunt for springs but found none. Mine look like cad plated springs, so I have no idea what they are. I would order a complete set of springs if I knew where to order

I am willing to try the KD NEEDLES but where on earth would you get them? Another question is if SM needles are rich enough to feed an L28 why on earth can't my baby L24 get enough gas As with most complex systems with many variables it may just be a tolerance build up. Maybe not. Motorman it is good to here you enjoy this thread. I often wonder if people get tired of me and this problem. I will look for some KD needles

I can try that as well. It will have to wait for my next day off...Maybe Saturday. Leak down test is on hold until I can get a new air compressor. Mine went kaput

UPDATE: I performed several vacuum related tests yesterday. More data, for those who are still with me. I Tee'ed into my manifold vacuum near the power brake tap. Warmed up I am solid steady at 17 in. I fiddled with the timing a bit so that may be why I am off from the 19 or 20 I had last time. When I drove the car, I saw nothing unusual with the vacuum readings as I moved along. Very steady all of the time, and responding to my inputs form the throttle as you would expect. When the popping happened, the vacuum was steady and the needle did not jump around. So I pulled it into the garage and sprayed carb cleaner around the gaskets, and no change was noticed in RPM Lastly I moved the SM needles flush with the groove in the bottom of the piston (although I know the FSM says otherwise) This make the car super rich at idle and it really struggled to hold a 500 rpm idle with so much fuel going through her. But the problem still happened. the LAST THING TO try with the carbs is to weigh down the pistons more so it is harder for them to rise as suggested before. I may try to hook up my GoPro camera under the hood with a flash light to see what the pistons are doing if I get sporty. I truly think my car is not getting the fuel it needs. THis is the reason: I got her up to 5000 rpm and she was popping like mad. I held her there at 5000 rpm still popping and with the ARF at the mid to high 16's. I yanked down the choke all the way this time and she went to 12.5 and took off. THat would seem to indicate that the needles are NOT rising ENOUGH! I have a sneaky suspicion that this is a far more mechanical issue than just carbs. But I am about ready to crush this problem with my wallet and a phone call to Datsun Spirit!!!!

I vote for an epoxy covered floor....HAHA It is what I use and it makes sliding very easy. Also, I will second card board. It makes it VERY easy and provides some cushioning.

Agreed When I redid my inner fender, I used a tube of stuff called plastic metal. It made the repair so very easy. I also recommend www.automotivetouchup.com they can match your OEM color VERY close. I have a thread on here somewhere that shows my inner fender repair. I had 13 or so holes in there from an AC install I removed.

Okay first things first. The distributor vacuum advance should be connected to the little vacuum nipple RIGHT BEHIND the front SU. The proper location for the large line coming out of the valve cover is the orange air cleaner. The hose from the crankcase that exists the block right below the dizzy should plug into the PCV valve on the balance tube. I will check out my three way vacuum valve to see where they are hooked up. One is definitely the expansion tank, I think one is the air cleaner, and the other is the small tube coming off the crankcase vent

Shouldn't there be a throttle lever next to the choke lever on the center console.

I need a moment. This is not fair. I had your car as a screen saver for a while.

Yup, 2 new sets of NGK's.

I asked Z therapy about the floats and Steve said they were spot on. Also bad floats would also show up at WOT, not just part throttle. I spent the night cleaning connections and hooking up a vacuum gage inline with my manifold. I had to run a line all the way into the cabin from under the hood, but that should suffice. My wide band responds to changes in the idle mixture screw immediately. I was running about 11:1 when I sent them off, and Steve said that his car would stumble badly off throttle and would lean out terribly the way I had them set (2.5 turns from the top). He said he went to a hair over three turns out and he drove his car for 100 miles just like that with no issues at all. I did not touch the carbs when I bolted them up. I went from running 11:1 at idle when I sent them off to 10:1 at idle due the extra turn or so out. Problem is exactly the same. OR at least similar enough I cannot tell the difference. The thing is if I run it 5 turns out, the engine will not run it dies. I would be willing to try a points type distributor if I had one Captian. I would be willing to buy a Mallory Unilite at this point as well. But I do not think it will make a bit of difference accept to lighten my wallet further. Although I do plan on running a Mallory for this engine build I have planned... Hummmmmm

Okay, I will ensure everything is cleaned and making good contact, but I am sure it is. The little flexible fabric looking wrapped wire in the distributor that goes from the housing to the pertronix plate may be dirty. I will also check to see if my coil is getting enough voltage as I drive it. More wires coming out of the hood! going to look like an over instrumented test mule before I am done!

Okay, I have checked the electrical schematic, how would one go about finding where the ignition is grounded? The coil gets its power from the tach, which gets power from the ignition switch. A weak spark could cause my issue, just need to check every ground in the ignition circuit. This is refreshing,as this is something new!!!

I will check the ground as best I can. I can honestly say I have not checked every ground on the entire motor. I will pull up a schematic to see where the ignition is grounded and see where I may be losing something. I get into the high 16's and 17's when it pops madkaw. I will measure my resistance through the coil again, but I am sure I hooked it up right. I think my coil is 3 Ohm so I bypassed my ballast resistor, but I will double check.

Not sure how I would do that? I have checked that my coil is getting 13+ volts, and I have tried two different coils. I guess I could wire in a voltmeter to the coil while I am driving. Not sure how I would measure spark intensity though As far as attachments to the coil, I do not have any capacitors attached to my coil or dizzy at all. I am using a Pertronix flamethrower right now. And I am bypassing my ballast resistor.

Well just looking at the cam lobes will tell me when the valves are closed but it will not tell me when TDC is on each cylinder. Not really sure it matters, as all I am really measuring is make up flow, but everything I have read says put it on TDC. Also, for those who have done a leak down test, did putting 100 psi in the cylinder spin the motor over.

Blue, you thinking is very logical. I actually ran with my brake booster plugged off at the manifold and this still happened. Did the same thing with my PCV valve blocked off and the same thing happened. I also checked the check valve in line with the booster,and it pasted the FSM check. I am just about ready to pull the head off the darn thing. I know there is lots of build up on top of all the intake valves. It is not unreasonable to think that I may have a burn valve. But I would think that would show up on a compression test. Still, I have replaced and swapped just about every single part I can think of. I am not so ham fistted at tuning that I think I have something that out of whack. I am going to do my vacuum runs tonight if it is not pouring rain. But not sure what I will do with the data. If I show my vacuum dropping off as my rpm rises under part throttle, what do I do? I will do the spray can of carb cleaner around the sealing surfaces as well and listen for rpm changes. If that does not show anything, well, then folks, I am going to admit defeat. The last test I will perform is the leak down test. Not sure how I am going to find TDC on cylinders 2-6 though. My plan is to run the engine until it is hot. Pull the plugs disconnect the coil remove the valve cover rotate the engine until it is on #1 TDC do leak down test on #1 Not sure how I am going to find TDC on #2-#6 though. I could stick something into the cylinder that is long and thin and when it stops moving down and starts going up I will know I am close. Guess that can work. But it will not be exact, it will only be close One question I have is when you put 100 psi into the cylinder, do you have to keep the engine from turning over?

Doradox, I hear you, and to the best of my knowledge, I do not feel any hesitation or missing at all right up until it starts to pop and stutter. If I never revved the engine past 4500 rpm I would not ever even know I have an issue. To add more weight into the lean camp, my plugs look light brown when I pull them out, not the nice dark patina you want to see.