TheCrazySwede

Yup, everything sits well. No gunk or corrosion either. I checked my vacuum via the port that connects to the brake booster and my gauge is hopping all over the place, suggesting a vacuum leak somewhere. Manifold is tight and all the gaskets on the Carbs seem to seat properly. Since this is a new engine (~1,000miles), could it be needing a valve adjustment after break-in? Perhaps that's what's giving me those wonky readings.

Yup, I checked the needles and seats and also made sure they were tight. I tested them one by one with pump running and when seated none of them leaked. I wanted to try lowering the fuel pressure down to 3psi to see if it made a difference - and it didn't. Floats are all set at 29-30mm (spec is 29-31mm) Yet I am still running rich with fuel dripping from the pump nozzles into the barrels. I also tried smaller size pump nozzles and same thing is happening. I do notice that even with pump and motor off, there's still dripping from the nozzle into the barrels for a few minutes afterwards.

Ok, so I tested my needles and all of them seat properly. Ran pump with one unseated top at a time and all the seated ones remained shut and never leaked. My fuel pressure is still within spec and hasn't been an issue before...but what can I lower it to? 3psi?

Hello fellow Z'ers, Recently started having an issue on my Z running really rich and I can see fuel dripping from the nozzle into the barrels. Car ran excellent for months; then suddenly went to start it and noticed my AFR in the 9's and noticed the drip. The motor is not stock; has a .495 lift and 290 duration, so keep that in mind. Idle Jets it ran - 65, but I also tried swapping in 62.5 and 60's and the AFR stayed the same. Mixture screws are 1.5 turns out. Fuel Pressure is right below 4psi (with 3.5 - 5psi spec) and was tested with two different gauges Floats at 30mm (within 29-31mm spec) Pump nozzle sizes tried: 40 and 50 It drips down from multiple barrels, not just one. Can't seem to figure out why this is happening since nothing was changed since it last drove fine. Any ideas where to start next? Thanks! Video: https://youtu.be/gCfc9WM56DE

Ok, it's been a while since I gave an update, so here it goes! Every wire in the car, from front to back, has been redone, replaced or discarded. The car runs on what is needed. No heater, no fan controls, no radio, no antenna switch - not even the fuel light was spared. The car runs on only what's needed, nothing more and nothing less. The issue with the idle and pilot jets is resolved, too. Idles and runs on all six cylinders now! I'm not sure what did it, but I replaced my filter, cleaned my tank, cleaned out the carbs as best as I could and messed around with the idle mixture - and eventually it worked! I've spent many hours now diving into every piece of literature I can find on DCOE carburetors and I've surely learned a lot to the point where I feel very comfortable working on these guys. What I couldn't find much on was what parts of the DCOE family (Weber, Mikuni, OER, Solex, etc.) is interchangeable - specifically talking about jets. What I learned is that Weber idle jets work as long as you get the appropriate seats for them. Mikuni Air Correctors work on these carburetors, too, and fit right into the emulsion tube. The mains, however, only seem to fit with OER ones. I went through a lot of different setups to find something that works for this engine and so far the perfect recipe seems to be: Mains: 135 Air: 160 Idle: 65(OER)/65F9(Weber) I am currently running 62.5 pilots, but it's a tad bit too lean when cruising. i've tried 70F8's and 70F9's and they're both too rich. My guess is that 65's should fit in perfectly, but they're still on their way from Japan since I'm going with the OER one. The F9 designation on Webers is the same as the OER. I also got a wideband hooked up now so I can get proper readings on this thing. At idle I'm currently sitting at 12.7-13 AFR, it goes up to 14 when cruising under 2kRPM (should richen up a bit with the 65's) and I get in the mid 12's at WOT, which seems to be the sweetspot for this engine.

I've tried swapping plugs and it's only that cylinder. Haven't tried swapping wires, but the wires are brand new MSD spark plug wires. It could be the dizzy, but I don' think the issue is there once the car is under load above 3500-4k RPM, which is weird. The cap looks good, but I'm gonna try replacing that next. Compression check comes out healthy and strong. If the valves were an issue, I'd imagine the issue would be more noticeable at higher RPM, but it seems to only be an idle issue. It actually runs much better at higher RPM, which makes me think it's an issue with the idle in the carb since the mains take over right about that mark.

I checked that and I get spark. The Cyl5 plug is wet and covered in fuel, whereas the others aren't. Still, unplugging Cyl5 does nothing to the engine and it still idles with 5 cylinders. I'm thinking maybe something is stuck (like the idle jet maybe?) and it springs to life once the mains kick on. Not sure why the plug would be wet, though.

So it looks like it's just Cyl5 now, so it idles on 5cyl. Removing the spark plug does nothing on this cyl. I replaced all my plugs and issue persists. When I removed plug 5, I noticed that it smelt of fuel and that it was a bit wet around the ring. Does this mean it gets fuel, but no spark?

I fear perhaps I might have to go down this route. i also don't have filters on my carbs yet - could dirt and crap have gotten in and clogged some bits up? Thanks for the advice! I feel like I'm always taking two steps forward and one step back, haha

I checked those and nothing seems blocked. Even swapped them with ones from running cylinders and got nothing. This is really odd... I read online that someone screwed the mixture screws in too tight once and something got stuck so it didn't back out when he started richening them. I highly, highly doubt that's my issue, cause these are brand new carbs and I've been very gentle with pretty much everything. I'm gonna head back to the spark issue again. I tested spark from the wires straight from the dizzy, but I only visually inspected each plug. I didn't swap plugs (or can't remember if I did) or replace them or anything like that. I got some spare ones laying around. I'll replace those plugs with new ones and try again. Doesn't hurt to try.

Wires are correct. I checked the idle jets and passage - used compressed air just in case. No change.

You, gentlemen, are Wizards. After reading both your replies over, it grew on me that something wasn't running right. You guys are on a Sage level of Z Ownership - found out I was running on 4cyl when idling! No change in idle if I disconnect Cyl4 and Cyl5. I tested both cylinders for spark and got it - compression test comes out good. Adjusting the idle mixture screws, however, don't do anything. These are two different screws on two different carbs. I can hear the engine acting differently if I adjust every other idle mixture, but the ones over Cyl4 and 5 show no difference. Now underload (perhaps when the main circuits kick in?) the car pulls hard and sounds like it runs on all six. Anyone have any ideas what's going on? Perhaps mixture screws got something stuck at the bottom?

Not really quiet, but not shouting by any means. It's a custom made Abarth exhaust tailored for my Z. It sounds a bit odd because of the way it was recorded + the way YouTube handles audio. Also helps if you have good speakers hooked up! (A laptop doesn't do it justice.) It sounds much, much deeper in person.

Quick update: Bought a new harness and I'm going to strip the car down and re-do all the wiring. Figure I'm going to want to do that anyway. Hoping I find something along the way. Here's the sound of the car with the carbs better tuned (Getting a hang of it!)

1. Yup 2. Nope - nothing disturbing alt from what I can see 3. Haven't tried running without alt yet. Will try this and report back! 1977 280z The stock motor had 0 issues. These problems appeared the moment I did the engine swap. That's why I thought I might have had an improper ground - but I can't find any. You know what, the other day my "door open, key in ignition" chime was sounding reaaaally funny. I just assumed it had something to do with the 16v+ being pumped out. But yeah, the voltage drop issue does sometimes appear when just inserting my key into the ignition - sometimes not. Usually it appears if I cause the volt drop, the turn off the car and remove the key and NOT WAIT long enough before putting my key back into the ignition. If I wait like 2-3 minutes, it usually doesn't do it, but if I insert the key immediately after having removed it (and doing something that causes the volt drop) the voltage drops again, even with no accessories on. Eventually comes back up again. Really weird. I haven't dug into much behind the dash yet. Maybe that's where my problem lies.