Guest Anonymous Posted December 6, 2001 Share Posted December 6, 2001 As some of you may know, I have a '75 280Z that doesn't run and I have been trying to get it fixed before I do anything else on my V8 project because I don't wanna end up having 3 projects that'll never get done instead of 1 that will. Anyways, I took the fuel injection off since a couple of the sensors were bad, along with the wiring harness and the air flow meter. I've got some Weber DGV's on the car now, along with a more carb-friendly fuel pump(I believe the package said 4-11psi). When I start the car, it idles for a little bit, but ONLY when the choke is completly closed. If I open the choke, even a little bit, it starts to sputter and after about 4 seconds it stops completly. It IS getting fuel and it is getting a VERY good spark, no arcing anywhere or anything, but I doubt this has anything to do with it anyways. Any ideas what the problem could be and how to fix it? Quote Link to comment Share on other sites More sharing options...
Guest Anonymous Posted December 6, 2001 Share Posted December 6, 2001 By the way, the intake says E88 on it if that helps. Quote Link to comment Share on other sites More sharing options...
randy 77zt Posted December 6, 2001 Share Posted December 6, 2001 idle jets are plugged in the dgv's.closing the choke pulls fuel from main jets down the booster venturi.best to get a couple of rebuild kits and a gallon of carb dip & rebild carbs.dgv's are good carb if you can get them jetted correctly.there is no carb that is jetted perfect from box.best carbs on a z are the 70 to 72 round tops.my old engine in my 77 280 was pretty quick after putting in new injectors,replacing injector plugs,gutting cat convertor,recurving distributor,putting on 2.5" tail pipe & muffler. Quote Link to comment Share on other sites More sharing options...
Z-Gad Posted December 6, 2001 Share Posted December 6, 2001 I didn't read anything about a regulator in your post. It sounds like your carbs are getting flooded with fuel. Pick yourself up an adjustable fuel pressure regulator at the auto parts store. They are usually pretty cheap for the 4-10 psi range. I'm not sure what pressure to run w/ the webbers, but the SU's run great set to 4.5 lbs of pressure. goodluck, mike Quote Link to comment Share on other sites More sharing options...
Guest Anonymous Posted December 6, 2001 Share Posted December 6, 2001 Well, we (me and my dad) got it running, but in order to do that, we had to advance the distributor ALLLLL the way. I put in a couple bucks of premium just to test it out, and it DOES run, but it has TERRIBLE accelleration. When getting it home, we left it idleing and looked at the inside of the carbs, and the primaries for cylinders 1, 2, and 3 are fine, but the one for 4, 5, and 6 is flooding. When my dad messed with the linkage by hand, the the car backfired and the carb backfired in his face, but if you leave it alone, it idles fine and doesn't backfire or anything when driving it around, it just runs like crap. Any other suggestions? And how do you adjust these carbs? I don't know anything baout 'em at all, when I bought the car the guy gave them to me for free. Also, I'll stop at the auto parts store today or tomorrow and get one of those regulators. And if any of you have cats and need a killer looking coller, those air flow meter to throttle body and air cleaner to airflow meter clamps work great(and no, it isn't tightened up all the way. It's on so loose the cat could drop it's head and it'd fall off, in case any of you were worrying). Quote Link to comment Share on other sites More sharing options...
Tim240z Posted December 7, 2001 Share Posted December 7, 2001 James, It sounds to me like the one carb is flooding because the float bowl is getting too much juice. Pull off the top of the carb and blow it out with compressed air. While you have the tops off, take out all the jets (one at a time) and make sure they're clean.*esp. the pump jets. Tim Quote Link to comment Share on other sites More sharing options...
jimzdat Posted December 7, 2001 Share Posted December 7, 2001 From my experience, (have run both the dual DGV setup and the triple DCOE setup) most Weber carbs are very unhappy with anything over ~4 psi fuel pressure--you definitely want a good quality reg in there to keep everything under control. Stay away from the 19.99 regs, they will usually crap out after a few months, then you're just spending more money on it--buy a good Holley or equivalent. If you can't find one locally, places like jegs or summit sell em. Another thing you can try is "Grose jets"--they replace the needle and seat assembly, using 2 little balls to shut off fuel flow--I've got them in my SU's, and they work great. At one time, Ztherapy used to sell the Grose jets for Webers, not sure if they still do or not. Good Luck, Jim Quote Link to comment Share on other sites More sharing options...
Guest Anonymous Posted December 7, 2001 Share Posted December 7, 2001 Heh, Jegs IS local lol. The main store is about 10 minutes from my house I'll have to stop by there tomorrow and pick one up. Thanks for all the help, I'll let you guys know how everything turns out if I get one tomorrow. Quote Link to comment Share on other sites More sharing options...
Guest Anonymous Posted December 9, 2001 Share Posted December 9, 2001 Nope, too poor . My uncle told me a T fitting with a smaller line going to the old return line from the fuel injection might help it out in the meantime, and smacking the carb with the back of a screwdriver while it's running might help if somethings stuck (he told me what it COULD be but I forgot). Quote Link to comment Share on other sites More sharing options...
jimzdat Posted December 9, 2001 Share Posted December 9, 2001 The T fitting idea might work, as it will allow some of the pressure to bleed off and return to the tank. The idea of "get a bigger damn hammer" adjustments to carbs always makes me cringe, but I can see where the idea comes from--he is thinking that the float may have stuck, keeping the needle/seat from closing; which is possible, or you could have a float that has "sunk"--some Webers have brass floats (in which you can hear the fuel sloshing if they leak), others have one made of some other substance I can;t think of the name of right now, and they can soak up fuel over time, and cause the same problem. Combine that with too high a fuel pressure, and you end up flooding the carb out. (About the regulators--I may have been a little too opinionated in my other post--in a pinch, the cheapo ones will work, they just tend to have a higher failure rate, so if you can find one of those, go ahead and useit--just keep an eye on things, just in case) Jim Quote Link to comment Share on other sites More sharing options...
Guest Anonymous Posted December 9, 2001 Share Posted December 9, 2001 Heh, he specifically told me to NOT use anything metal, just something lightweight to knock the carb around to loosen things up if anything is stuck. About those regulators, I can't even afford a $20 one, I've only got $10, so I was gonna see if I can get some cash today just for a cheap regulator to see if that fixes anything, instead of buying an expensive one and finding out that wasn't the problem. I understand what you mean about the cheap ones though, you get what you pay for. As a matter of fact, when I get this car running, my new idea is to leave it alone until I save a buncha money up, buy alot of the stuff I would need for a V8 swap, and instead of putting the V8 in my '79 ZX, put the V8 in the '75, and put it's engine in the ZX. Quote Link to comment Share on other sites More sharing options...
Guest Anonymous Posted December 12, 2001 Share Posted December 12, 2001 Heh...Dumb question...How do I do that? I know you loosen the screw and turn the distributor, but what do I set it to and how do I know it's at the correct setting? Quote Link to comment Share on other sites More sharing options...
Tim240z Posted December 12, 2001 Share Posted December 12, 2001 James, If you don't own a timing light, then just loosen the distributor and keep playing with it until the RPMs are the highest they will go. This will at least get you in the right direction. But from your original post, it seems that it's running too lean. Make sure that your idle jets aren't clogged with varnish or gunk. Pull off the top of the carb and take them out and clean with carb cleaner and compressed air. Also, if they were originally set up for a 240, they will be lean on the 280, but not badly enough to prevent running. Tim Quote Link to comment Share on other sites More sharing options...
Guest Anonymous Posted December 13, 2001 Share Posted December 13, 2001 Allright, I got the regulator and it's on 3.5psi the car idles way better and I can open the chokes all the way now, but only for a few seconds and then the car dies, and every now and then it will backfire through the carbs. I am positive there are no vacuum leaks. Also, I have a vacuum line running from the distributor directly to the manifold, otherwise it will barely idle and backfire through everything...alot. Any ideas? Quote Link to comment Share on other sites More sharing options...
Cruez Posted December 13, 2001 Share Posted December 13, 2001 Backfiring through the carbs?....make sure the ignition timing is correct... Quote Link to comment Share on other sites More sharing options...
Guest Anonymous Posted December 17, 2001 Share Posted December 17, 2001 Welp, advanced the timing as far as it would go without grinding out that little slot (I loosened the bottom plate and made it so I can advance the distributor even more) and it idles lower, doesn't backfire, revs faster, but still runs like crap. I took the top off the carb and nothing was wrong at all. It was surprisingly clean, nothing was clogged or anything. Now I am completly stumped. I hosed it down with carb cleaner anyways, ran a little better, but still ran bad. Gets HORRIBLE gas mileage, and after driving, that carb has white smoke coming out of it, but only a little. Any ideas what the problem could be? Think I should just fix the rust and put a V8 in it (which IS my plan in the future anyways)? Quote Link to comment Share on other sites More sharing options...
fl327 Posted December 18, 2001 Share Posted December 18, 2001 do it. Quote Link to comment Share on other sites More sharing options...
Mikelly Posted December 18, 2001 Share Posted December 18, 2001 James, You need to get documentation on those carbs and how to adjust them.. The carb running 4-6 sounds like it is WAY out of adjustment. You need to learn how to adjust the carbs and then sync them up to each other or you will never be happy with that setup... Go to a borders book and find a weber manual in the autotech section of the store. Mike Quote Link to comment Share on other sites More sharing options...
Guest Anonymous Posted December 18, 2001 Share Posted December 18, 2001 Dunno much about L28's but isn't it possible that his distributor is off a couple teeth? Of course this is impossible in some cars but like I said above... Quote Link to comment Share on other sites More sharing options...
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