PETEW

I put in a larger pilot to see what would happen. I wound up going to a 65 because the 62.5 I have are hand reemed and I have heard they are very inconsistant at best. I took the car out for a run. It is running pig rich down low. 10's and 11's. The mid range stumble is all but gone but is still leaning out badly. I am talking 16-17 range. I am going to try the 62.5 or maybe 60 pilots. I am not sure what to look at next. The overly rich pilot is obviously covering the mid throttle problem I am having. But I do not know what it is. Full thottle pulls cleanly above 3k rpm and O2 level is mid 12s. Any ideas? Thanks.

I have the new venturi's in and the Mikunis seem to run better with them in. I am still getting the bog when I start to lay into the throttle in lower or higher rpm. It almost seems like I need a bigger Pilot Jet. My idle is good and I am getting a mid 12 on the O2 sensor for idle. Light throttle applications (cruising) stay similar in O2 levels, as soon as I start to press the throttle to accelerate some my O2 sensor starts to lean out (14-15 range). If I get into the throttle more it goes off the readable range on the O2 sensor and bogs. When the car is floored it pulls nicely and cleanly with a high 11 to mid 12 oxygen sensor reading. Should I go to a larger Pilot Jet? I have a 57.5 in there now and was thinking a 60 or 62 might help. Is there another adjustment I can look at? Thanks for any help.

I had to go to a bigger main to keep O2 levels at a safer spot. I am now at a 165 main and 210 air jet. O2 levels are in the 12-13 range now. I am changing the outer venturis today and hoping it solves my bogging issue. I will let you know. Thanks.

Thanks for the help ryant67. The motor has a 2.8 liter with a p90 head, doomed pistons and mild cam. 6-1 header and 2 1/2 exhaust. I also went to a 280zx ignition. The Mikuni carbs are running with a 57.5 pilot jet a 160 main and a 200 air jet. the pump jet is a 140. I have the idle mixture screw 1 1/2 turns out. I just hooked up a wideband to the car to dial the carbs in better. Everything seems to be inline but during the transition to full throttle the sensor goes lean and the car stumbles badly. I went to a 150 pump jet and had no change. From what I have read it sounds like it is a air velocity issue and I should switch from the 37 to a 34. I am hoping this will rid me of the horrible stumble I am having when going to full throttle. Where do you order your Mikuni parts? Thanks, again.

Hey guys, I want to switch the outer venturi's in my Mikuni ph44 from the current 37 to the smaller 34 I have. I am not sure if you do this from the front taking the inner venturi out first or if you have to remove the carbs from the intake and take the venturi out from the back side. Any advice would be appreciated. I seem to be getting closer to getting these dialed in and I think the big problem I have on the transition from low thottle to full is air velocity. The motor just can't handle the bigger outer venturi, it seems. Thanks for the help.

Hey guys just wanted to give you a quick update. I went over everything, again, on the car. Checked gland nut, checked all bolts and nuts holding the back of the car together and found nothing loose or missing. I bought a second set of 280ZX half shafts (to have a spare) and decided to change the drivers side. It seems to have helped. I have not had a lot of time to drive it, but from what I can tell it has helped. I think I also need to do a Ron Tyler mount and keep the diff from moving around. I will keep you guys up to date and hopefully get this thing quieted down. Thanks for all the help.

Mike, this thing is going to be a beast! That thing was ludicrous with the 2jz. What kind of power were you making with that motor? The torque difference should be the main thing, right? Good luck with this set up, and stay safe.

I added another bottle of friction modifier to the diff. I will see if that makes the noise go away. If not I have another 280ZXT axle here. I will replace the driver side to see if that makes a difference. If not, then I will start looking for other options.

Well, the verdict is in. The shaft has plenty of movement throughout the range. I dropped the coil over perch as low as it could go and moved the shock all through it's movement and pulled on the shaft multiple times. it was free every time. I am really stumped. When I hear the popping (banging clanging or whatever you want to call it) it is coming from the drivers side. I also checked the other side to see if it felt different, which it did not. I also spun the wheel to see if I ever felt any binding at some point and I did not. I guess it is coming from diff. My big concern is it didn't do it when I first started driving and seems to be happening more and more. Maybe I will try and add another bottle of friction modifier. It just amazes me that the sound always seems to come from the drivers side. Strange.

It is hard to tell from the video, but yes it is a good sounding POP on my car. When it first happened I was thinking LSD but it doesn't do it consistently. I am in the process of doing tests on the CV, to make sure it is not binding in some way. RebekahsZ did the extra tube of friction modifier help? What ever this sound is, it is really upsetting. I keep thinking I am breaking something when I hear it. Thanks for all the help guys. I appreciate the input. I will report my findings tomorrow.

I am not hearing the CV itself bind. I am hearing the result of the binding. You know, clunk, clunk, kind of stuff. It is quite unnerving. I am going to do some tests today to see where the issue is exactly. I am 99% sure it is binding from the CV, but will make sure of it today. If it is, then I will either disassemble the cv or take it to a machine shop to have the shaft shortened.

I should also note that I never heard reversing the cage from Ross or got instruction like that with my adaptors.

Thanks for the reply NewZed. I noticed this statement in post #34 "Or maybe you need to reorient the cage to gain back the 3/8" length (assuming you've done this minor mod as recommended by Ross)" So it looks like Ross did recommend reversing the cage on the one CV. I just want to make sure this does not cause any limitations to movement. Thanks.

The other thing I thought of doing was taking 1/8 to 3/16" off the Modern Motorsports adapter. I am pretty sure there is enough meat there to do that, and have no issue. I could be wrong though. Any thoughts on this method? Thanks for any help.

Does anyone else have binding issues with 280zx cv's? I was thinking of getting the shaft shortened by 1/4" and having them scotch keyed. Thoughts? I am also buying a second set of shafts. Has anyone had trouble with one set and not another? Just trying to figure out what I can do to get the car back on the road. Too fun to drive to let it sit. Thanks.