Guest nsadhal Posted March 30, 2005 Share Posted March 30, 2005 Hi, all... I posted a few weeks ago on zcar.com but didn't get much help. I have a 240Z with an L28 block, E88 head, and '72 round top SUs with smog equipment and an e12-80 distributor. My car had been running fine and I had just gotten the mixture close to perfect. I had recently replaced one of the floats, the distributor cap, and rotor (but I don't think any of those lead to my problem. After driving around for a few hours (cause I was happy to have my car running so well), I got home and checked the plugs. The front ones were a little darker than I'd hoped, so I leaned the mixture by 2 clicks. I put the plugs back and all... then went to start the car up again. It ran really rough as if the timing was way off or something. After running for a bit it just died and wouldn't start again. It also can't really hold much of an idle. Things i've figured out now: It only starts up when cold, with the choke all the way on. Once it warms up a bit, it won't start at all. Also, if it's running, and it warms up, it will die. It won't idle at all, and even has trouble running if you keep the revs up... throttle response with no load is awful... I haven't even tried putting load on the engine. I checked the timing at 3000 rpm and it's still around 35 degrees (where I had set it). I can't really check the idle timing since it won't idle. I checked each of the spark plugs leads for spark with the magnetic pickup on my timing light... they all strobed. I tried shutting off either carb by lifting the piston all the way to see if one carb was causing the problem... but neither affects the behavior much... (too rich?) I can't figure out what could have happened... I don't see any loose vacuum lines and whatnot... A while later I noticed a very minor fuel leak at the front carb... after shutting the car off there was white smoke coming out of the front intake... this only happened days later... I fixed the fuel leak and never saw the white smoke again (?). Anybody have ideas on where I should start now? Could there be something wrong with my internals? Quote Link to comment Share on other sites More sharing options...
Thumper Posted March 31, 2005 Share Posted March 31, 2005 I would look at the simpler things first before going into indepth stuff. I would remove the spark plugs and put new ones in and new spark plug wires. Especially if its been atleast a year since last time they were replaced. It either sounds like spark plug wires have been put on wrong or they came apart inside of the boots. The spark timing is 1-5-3-6-2-4 rotating counter-clockwise Quote Link to comment Share on other sites More sharing options...
Guest nsadhal Posted March 31, 2005 Share Posted March 31, 2005 I've double and triple checked the firing order. the plugs have less than 3000 miles on them. NGK BPR6EY I think (the v-power ones) i think the wires are okay, i don't think they've come apart inside the boots, but i'll check them again... I can try changing the plugs and wires... are there any stores that carry the NGK wires so I don't have to order them? Quote Link to comment Share on other sites More sharing options...
Guest rick458 Posted March 31, 2005 Share Posted March 31, 2005 Check the nuts on the induction IE, the intake , Balance tube , egr etc My 260 was doing the same thing.I could tune it up cold , Or I could tune it up hot but not both. when I pulled my induction off I could see carbon/grease tracks on all the gaskets I was fighting a different air leak at different temps. I would also check the cap and coil connections and be sure your suction pistons are free. Quote Link to comment Share on other sites More sharing options...
Guest billyzbear Posted March 31, 2005 Share Posted March 31, 2005 Two turns on the carb is alot. Do 1/4 turns at a time. Go back to where it was and then 1/4 turn up. SU's are a good carb. It will take sometime to get the "feel" for them. You could try trans fluid in the top of them instead of oil. You mite want to check your leakage for wide open throttle and adjust bump stop by pedal. These are often off. Quote Link to comment Share on other sites More sharing options...
Guest nsadhal Posted March 31, 2005 Share Posted March 31, 2005 not 2 turns, 2 clicks. that's like 1/6 turn or something. i've put it back to where it was since then... the thing is, this happened suddenly... like one minute it was running fine, and the next minute it wasn't... like something broke. so far it's sounding like my best bets are the plugs/wires... but even that i can't explain... they seemed fine. You mite want to check your leakage for wide open throttle and adjust bump stop by pedal. These are often off. I don't know what this means. Quote Link to comment Share on other sites More sharing options...
Guest nsadhal Posted April 6, 2005 Share Posted April 6, 2005 well, i think i figured out what's going on... sorta the rear 3 cyls aren't getting any fuel, but the fuel system is good up until the carb.... i started turning the mixture nut just to see what the setting was at, and it kept turning! it didn't stop after like 3.5 turns or whatever.... it just kept going! both directions... Quote Link to comment Share on other sites More sharing options...
Guest rick458 Posted April 6, 2005 Share Posted April 6, 2005 Sounds like your suction piston is stuck, spray the throat with PB Blast or Liquid wrench, WD 40 or what ever is your fav then take something soft, flat and strong slip past the choke plate and Gently and smothly ease up on the bottom of the piston, take the cap off first, make suer the carbs oil level is right as well. Marvel Mystery oil or 20 wt works well. Quote Link to comment Share on other sites More sharing options...
Guest nsadhal Posted April 6, 2005 Share Posted April 6, 2005 actually... yeah never mind about that... the choke was on... i'm an idiot. so basically, now i'm back to the beginning... well, i reckon i'm not getting any fuel to the back 3... Quote Link to comment Share on other sites More sharing options...
Guest billyzbear Posted April 6, 2005 Share Posted April 6, 2005 Ya sometimes the chokes will stick. I used springs to help them return. It was a long time ago but it was one spring per side. From the linkage to heatshield. Sorry I didn't get back to ya sooner. I didn't get an email. Quote Link to comment Share on other sites More sharing options...
zeiss150 Posted April 6, 2005 Share Posted April 6, 2005 If your back three arn't getting fuel, check the nozzel on your rear carb to see if its cloged. That happend to me once ... I bought an "SU" carb rebuild kit and it came with fuel lines that go from the float bowl to the nozzel. Well they would have worked great if it would have been fuel line... It was some kind of stupid wind sheild wiper line the gas totally disinegrated the inside of the line and pluged up the nozzel. I don't know if that will help but thats where I would check. Rock on Z people! 72 240, L28 F54 flat top N-42 head with schnider cam 273 460 72 SU'swith SM needels, MSA Header 21/2 inch exaust, 82 zx dizzy, 78 5 speed ... RWHP I don't know ... but it sure is fun to drive:twisted: Quote Link to comment Share on other sites More sharing options...
Guest nsadhal Posted April 6, 2005 Share Posted April 6, 2005 It was some kind of stupid wind sheild wiper line the gas totally disinegrated the inside of the line and pluged up the nozzel. I don't know if that will help but thats where I would check. Oh my goodness, I think that might be what happened. My carbs had really fat fuel lines on them, and they kind of make my chokes difficult to operate... so after I changed the float on the rear carb, I put a new "fuel line" from a rebuild kit on... it looked like the proper thin kind... But today I went to check if maybe there was obstruction in the fuel line and it totally came apart when I was trying to take it off. The ends of it were totally stuck to the carb and the float bowl... I had to take the remains off with a knife. I put my old fuel line back, but yeah, okay... I'll take the nozzle apart then. The brand of carb rebuild kit was "HYGRADE" btw... Quote Link to comment Share on other sites More sharing options...
Guest nsadhal Posted April 6, 2005 Share Posted April 6, 2005 Hmm, well I'm still not sure what's going on... I wasn't really able to get the jet off to clean it properly because the screw connected to the choke was really tight and at an odd angle. The screw head isn't really in the best shape either. I was able to run a thin wire through the jet and have it come out the other side though. I guess it could still be gummed up though. I can see fuel in the jet when I take off the domes though. I also checked the float level again and it's dead on. I messed around with the carbs a little and got the car to a rough idle, even when warm... so hopefully I can diagnose some more. This is what I know: - something wrong w/ rear 3 cyls... probably due to fuel delivery (?) - all 3 rear plugs are wet and oily (smells like oil) - pulling any of the plug wires on the rear 3 while the engine is running causes nothing to happen... i.e. none of those cylinders are really doing much. - the car runs better when i disable the rear carb by lifting the piston - when i let the piston back down, the car runs even smoother for a second and then it starts idling pretty rough and will slowly die - if i disable the front carb, the car will run for a little on the rear carb if I increase the throttle, but really badly, and then still die. Also, when trying to do that, I can hear a loud hiss, but I don't think it's a vacuum leak (?) ... or is it? maybe I have a leak at the intake manifold? I was trying to do that carb cleaner spray test, but didn't have much luck. I'll try it again later. Thanks. Quote Link to comment Share on other sites More sharing options...
Guest nsadhal Posted April 22, 2005 Share Posted April 22, 2005 In case anyone cares... I think I figured out the problem... Here's what I posted on zcar.com just now: Well, you may have seen my posts a while back about how my car wasn't running well:http://www.zcar.com/forums/search.php?f=1&search=nsadhal&globalsearch=0&match=1&date=0&fldauthor=1 (don't bother reading) It's been like month now... So I had some free time today and decided to pull the valve cover (something I should've done a long long time ago), and what do I see? Found this guy floating around in the head: So uh, I looked at the manual and it looks like I should be able to fix this without taking the head off, but I don't totally see how to do it. I can't tell if I'm missing the "split collar" (?) or not. It looks like it's in there, but I'm not sure that little thing is it. I also can't figure out what keeps the other ones together. It looks like this valve is sunken, and that's what let the valve rocker guide escape? Also, could I have done any damage to the valve or piston? i.e. could they have run into each other since this happened? It seems like this would pretty much explain everything? Why all 3 cylinders weren't getting any fuel and whatnot? Quote Link to comment Share on other sites More sharing options...
zeiss150 Posted April 22, 2005 Share Posted April 22, 2005 Nsadhal, Let me be the first one to tell you whats going on here. Your rocker arm slid off of the valve springs. now you may have a pretty serious problem here. the only way the rocker arm can escape like that is if one of two things has happened ... 1. If you "pop" a valve seat and it keeps the valve from re-seating that would hold the valve spring down and alow enough play for the cocker arm to "jump off" If this is the case the you would have to pull the head and replace the valve, the valve seat, and posibley the valve guide. also If the valve was hanging down low enough the it could make contact with the piston and that would be really bad! You'll know if it did because you'll have a big valve shaped mark on the top of the piston. You should be able to tell if this is the problem by compairing the hight of the valve spring without the rocker arm to another valve spring that doesn have a rocker arm but WITH NO TENTION ON THE ROCKER ARM (i.e. the cam lobe would be facing up). If they ARE the same hight then you dodged a bullet and this is not your problem. 2. This is the most likely sinerio... the rocker arms are held in place with a "lock nut" that is just above the rocker arm height adjusting nut If this lock nut comes loose and the adjusting nut spins down and becomes loose then your rocker arm can pop off. By looking at your picture your came lobe suffered no damage and the rocker arm shim (the little piece in your blue rag) also doesn't seem to have any damage, as long as the rocker arm isnt damaged then all you need to do is put them back together and re-adjust the rocker arm hight (intake 10mm exaust 12mm HOT)... in order to get the rocker arm back in place youll need to use a long screwdriver or something long and hard to pry it back in place ... just be carefull not to scratch the cam lobes or rocker arm hardend surface. If its # 2 its and Easy fix... If its #1 ... you might need a new engine (doubtfull but worst case sinerio) at the least not a fun problem to have. Good luck and if you have any questions let me know ... P.S. #1 happend to me Rock on Z people Matt- Quote Link to comment Share on other sites More sharing options...
Guest nsadhal Posted April 23, 2005 Share Posted April 23, 2005 Thanks zeiss, actually the valve is lower than the other closed valves. I can put it all back in place, but I can just as easily remove it with a finger. Sounds like I may have a bent/stuck valve then...? Is it possible for me to pull/replace the valve without taking off the head? Quote Link to comment Share on other sites More sharing options...
evildky Posted April 23, 2005 Share Posted April 23, 2005 you can try pulling up on the valve if it's stuck but if it's bent and has t be replaced the head is coming off, a good idea would be to find yourself an E31 or whatever head you want and have it freshened up at a machine shop and you can do the swap without as much downtime Quote Link to comment Share on other sites More sharing options...
Guest nsadhal Posted April 23, 2005 Share Posted April 23, 2005 funny thing about that... I have an E88, and had a spare one that came with the car... it was old and nasty (rusting valves, things that crawled up and died in there), but it looked complete... being the genius I am, I sold it for $50.... sigh. Quote Link to comment Share on other sites More sharing options...
zeiss150 Posted April 23, 2005 Share Posted April 23, 2005 sounds like its time for that turbo build you've been dreaming about! Good luck Rock on Z people! Quote Link to comment Share on other sites More sharing options...
shamus001 Posted April 22, 2023 Share Posted April 22, 2023 Check your temp gage. My Datsun did this, it would drive for 5 minutes before overheating. Your thermostat can be checked by removing it and placing it into a pot of boiling water. If it pops open, it's good. Of course if your sensor is bad, that's a $10 fix. Not sure if your fuel return is hooked up, but if you don't have your fuel lines wrapped, you will get vapor lock with your 240z. So it will sputter and due then only start up when it cools down. Buy fuel line insulation and install it. Quote Link to comment Share on other sites More sharing options...
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