PurePontiacKid Posted March 23, 2012 Author Share Posted March 23, 2012 I swapped the float bowls over to the 3-screws, so those didn't change and weren't the cause lol Quote Link to comment Share on other sites More sharing options...
Tony D Posted March 25, 2012 Share Posted March 25, 2012 "I don't believe its rich because there is no smoke coming from the tailpipe and the spark plugs are white/tan." First off, on a non-catalyzed L-Engine in a Z-Car, you will not see ANY "black smoke" out the tailpipe until you are in the low 10:1, high 9:1 AFR's. This observation has been confirmed countless times by dyno runs with WBO2's connected both onboard the car, and with the dyno's Horiba or other 5-gas analyzer/AFR setup. This myth needs to be SLAIN! It's repeated FAR to often to be healthy. As we see in this case it is again confirmed apparently. Sticking Nozzles: one nozzle stuck even 2mm down in the well can cause the issue. I had this issue with my 260Z for YEARS until I finally had the time to take the damn things off and find the stuck jet. Now every time I use the starter circuit, after it's running I physically verify the nozzles have returned to their original position. Quote Link to comment Share on other sites More sharing options...
Tony D Posted March 25, 2012 Share Posted March 25, 2012 "I don't believe its rich because there is no smoke coming from the tailpipe and the spark plugs are white/tan." First off, on a non-catalyzed L-Engine in a Z-Car, you will not see ANY "black smoke" out the tailpipe until you are in the low 10:1, high 9:1 AFR's. This observation has been confirmed countless times by dyno runs with WBO2's connected both onboard the car, and with the dyno's Horiba or other 5-gas analyzer/AFR setup. This myth needs to be SLAIN! It's repeated FAR to often to be healthy. As we see in this case it is again confirmed apparently. Sticking Nozzles: one nozzle stuck even 2mm down in the well can cause the issue. I had this issue with my 260Z for YEARS until I finally had the time to take the damn things off and find the stuck jet. Now every time I use the starter circuit, after it's running I physically verify the nozzles have returned to their original position. Quote Link to comment Share on other sites More sharing options...
HowlerMonkey Posted March 26, 2012 Share Posted March 26, 2012 (edited) Then I guess the 280zx runs richer than 10:1 when you unplug the 02 sensor......which causes black smoke when the car is run. At Z shop of miami, we used to coordinate test drives for the first services of the day to have at least two cars. Following a 280zx with bad 02 or it unplugged always netted black smoke. Edited March 26, 2012 by HowlerMonkey Quote Link to comment Share on other sites More sharing options...
PurePontiacKid Posted March 26, 2012 Author Share Posted March 26, 2012 Yes, but wouldn't enough fuel going through the engine to essentially flood it be lower than 9:1 AFRs? I've checked the nozzles, they come back up flush with a crack of the throttle. I don't have a choke hooked up, either. Btw; problem came back two days after I swapped the bodies... have installed another FPR and now the fuel pressure is at 2.5psi and is still doing it. Quote Link to comment Share on other sites More sharing options...
Tony D Posted April 1, 2012 Share Posted April 1, 2012 Then I guess the 280zx runs richer than 10:1 when you unplug the 02 sensor......which causes black smoke when the car is run. Yes, that is correct. What are you asking? I think it was pretty clearly stated. What is the confusion? Quote Link to comment Share on other sites More sharing options...
HowlerMonkey Posted April 4, 2012 Share Posted April 4, 2012 (edited) You guote a statement made from 25 years experience and observation and try to call it a question? There are plenty of other threads in which you can do this. This is not one of them. Edited April 4, 2012 by HowlerMonkey Quote Link to comment Share on other sites More sharing options...
Tony D Posted April 4, 2012 Share Posted April 4, 2012 My statement was posted to dispel the myth that "all was right if it doesn't show black smoke"---I quantified it for those who never looked at the realities of the situation: you won't get black smoke until you are in the low 10:1 region. That is FAR from "all is ok" territory---to the point that not showing smoke doesn't particularly prove anything in regards to mixture other than you aren't in the 9-10:1 range of AFR's. And most tuners will agree that 11:1 is way rich for most N/A, and in some cases 12:1... If "I guess" is a statement, it sounded like a question, or were you merely restating the obvious? I was confused by your retort. Your second does nothing to clarify it. Quote Link to comment Share on other sites More sharing options...
Tony D Posted April 4, 2012 Share Posted April 4, 2012 And note I qualified the statement if UNCATALYZED L-Engines... If you got a cat and it's working hard whilst still puffing black out back, you are well into the 9:1 and lower AFR Range. If you see black smoke out the tailpipe it isn't "a little out of tune" it's WAY OUT! And if you're puffing black with a catalyst, it's TERRIBLY out and melting down that expensive brick in the catalyst... Black Smoke=Terrible Tune. Quote Link to comment Share on other sites More sharing options...
srgunz Posted April 7, 2012 Share Posted April 7, 2012 We fixed one like that. Turned out real simple. Took off air cleaner, said put gas pedal to floor. View throttle plate position with flashlight. Found plates not open fully. Loosen linkage slip bolts, push throttle by hand to fully open. Retighten slip bolts, road test, done, runs like a raped ape. Quote Link to comment Share on other sites More sharing options...
PurePontiacKid Posted August 11, 2012 Author Share Posted August 11, 2012 Just thought I'd come in here again. still having issues. almost seems like an ignition problem now that I've got the other problems sorted (fuel percolation) Have since swapped to a stock fuel rail, set the float levels (per http://datsunzgarage.com/engine/ ) changed fuel regulator again (solid 3psi), adjusted needle height, adjusted the mixture nuts, synced the carbs, swapped distributors, checked timing (16* btdc), and I'm sure a few other things I've tried to no avail. (have also checked for getting WOT at the butterflies.) car runs AMAZING at everything less than 4k rpm. It's extremely responsive, idles smooth as hell, gets 20mpg (even beating on it). My only issue is WOT at 5-6k rpm. could it be my needles? traded a friend my stock ones for the set he got with his rebuilt SUs. They're stamped XD (or DX, been a couple weeks since I looked at them.) Does anyone know anything about these needles? I'm trying to find a stock pair locally I can borrow to see what that does. engine bay currently looks like this (except with dual K&N filters, running without them makes no difference): Quote Link to comment Share on other sites More sharing options...
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