ben92

Hey Andbir, cheers for the write up! Just checking, is this what it should look like when you say 'throttle plate covering the first progression hole'? I've shone a light down the intake to work out where the plate sits. I haven't seen any guides that mention setting the idle like this, I'd only heard of going in 1/4 or 1/2 from where the idle speed screw starts activating the arm. Setting it like I've done in the photo is about a full 2 1/2 turns in opposed to 1/2 a turn in? I'll report back once I've been able to fire her up again but I wouldn't have thought to increase the idle speed when I'm already idling pretty high and rough.

Cheers Dave for the suggestion, definitely should have tried that first really. I did try doing exactly that this afternoon with a can of fuel I got today, and I got the car running, but still not well and not a noticeable amount better than before. Which leads me to believe the old fuel could use replacing, but the tank / old fuel / lines definitely aren't a huge problem and causing poor running. The dodgy fuel lines in the engine bay are definitely for testing only - I'll make another proper hard line setup once I figure out which set up to go with The electric pump is aftermarket supercheap junk as far as I know. No brand or marking on it, and it was doing functionally nothing at all last weekend when I ran all my tests. I might get around to bench testing it on the weekend just out of curiosity, but for now that's why I've removed it for now and only have the mechanical pump installed. This wasn't the original plan, but at this stage it doesn't look like switching out the mechanical pump for an electric one would really change anything in terms of trying to get a smooth, healthy idle in the garage anyway. The best I could manage tonight was getting a somewhat consistent idle, albeit still with a lot of popping and backfiring that sounded too unhealthy for me to want to let the car run long enough to warm up. I don't know how much damage all the sputtering and exploding is doing so I don't want to over do it? Revving still gives a bunch of different results; sometimes it hangs for a few seconds, the fan usually kicks in hard, there's usually a lot of backfiring and occassionally it would kill the car altogether. To get it to idle consistently-ish I adjusted the timing and the weber's mixture screws and seemed to be going in the right direction, but yeah, all the excessive banging concerns me too much to let it just idle for too long. I've definitely set the webers idle correctly, that's simple enough. Every tuning guide mentions that for the weber's mixture screws you start with 2 turns out from 'seated' - but I don't have the slightest clue where 'seated' is. The springs are the only thing that seem to be adding resistance to that screw so the mixture at the moment is pure trial and error and with the messy idling it's pretty hard to gauge whether turning in / out is making the idle better or worse. The fuel pressure from the mechanical pump is still at a solid 5 PSI - still can't figure out if putting the regulator after the mechanical pump with no bypass is a good idea, so I haven't tried that either. Could the extra 2 PSI cause running issues? I could fire it up again and attempt to re-set the timing with a light if the idle stays in a good range. I could also get yet another fresh set of spark plugs and see if that helps, and play around with the mixture / synchro tool some more. Perhaps going through everything another time could give better results, but at this stage, unless I'm missing something, this is all stuff I've tried a lot over the last few years, so I'm tempted to find a local mechanic that actually knows what they're doing and might be able to diagnose something I can't?

So, unsuprisingly, a new set of carbs didn't magically get the car running decently. After installing everything and trying to dial in a baseline tune it ran worse. A lot worse. Backfiring from the carbs and the exhaust, idling at 800, then 1600, then dying, it was all over the place. I tried all the usual things - adjusting timing with a timing light, attempting to sync the carbs, adjusting idle screws, running it with / without the aftermarket electric pump, checking for vacuum leaks...but no success. Putting a syncro over most of the air intake tubes killed the thing and it was so hard to keep it running consistently that I couldn't work out what to even attempt. I gave up for 3 months, apparently, figuring that I'd have to send it off to someone who knows a lot better than I do. But now, with a house move to a place that has an incline driveway looming (meaning the car needs to be driveable to be able to get it up the driveway to store it), I figured I'd do a last run of somewhat methodical tests. The first idea was to drain the (possibly) old fuel, just in case all it really needed was fresh fuel. When I unplug the fuel send port on the tank, the fuel almost just dribles out. The return post sends fuel flying out as you'd expect. So, first question - is that to be expected? I've got a late model 260z tank, so as far as I can see the send port is driver side, return port is passenger side. Ignoring that, the second test was to work out what sort of fuel pressure I was getting - perhaps inconsistent pressure was causing inconsistent running. I'd bought a PSI gauge, so may as well use it. With the key in the 'ON' position, the aftermarket electric pump makes a big racket, but does functionally nothing. I tried switching tank outlet ports, fuel lines, fully charging the battery, and also blowing compressed air down the lines / tank ports incase there was a blockage (there isn't, as far as I can tell). The electric pump should definitely be able to prime the whole fuel line on it's own though, right? Even with air in the lines, it should still be strong enough to push fuel from the tank to the carbs with decent pressure? Or am I asking too much of it? Not knowing the answer or wanting to buy another electric pump without doing more testing, I decided to take off the pump and blow / suck air through it. I wanted to know if I had the pump wires disconnected, or the pump was broken, was it actually blocking the line and stopping the mechanical pump from doing it's job? Turns out I could blow air through it, but it makes a sort of trumpet noise at the start - like there's a bit of resistance but then a gate stays open once the fuel is flowing. I could probably look into how these things work but for now the tests continue. Next test - seeing as the triple carb set up has never been trialled without the electric pump after the tank, how would running just the mechanical pump go? Plenty of cases of people just running the stock mechanical pump with triple webers it seems, so worth a shot. After a long while of turning the engine over (side question - is it bad to keep the engine turning over without it firing up? How much damage have I already done over the years?) the single, dead head line was primed with a consistent 5 PSI. Eventually I throttled the carbs and it fired right up - revving straight up to 2000 rpm, sitting there and backfiring a little. Not wanting to touch anything and hear it backfire all over the place today, I've turned it off for the day to try and work out the best way forward again. I've got to wait a day for the threadlocker on the fuel pressure regulator ports to set, so I'll charge the battery again over night and adjust the idle screws on the carbs a little before firing it up tomorrow hopefully. If it runs consistently, then perhaps I can at least start to dial in a tune? I also realised I got distracted and never ended up draining the tank, so it may still have stale fuel. So - last question - can I install this non-bypass, dead head fuel pressure regulator between the mechanical pump and the carbs like I've got pictured below (with the routing of where the clear hose goes, just with everything connected properly)? Supposedly the webers want 3-3.5 PSI, and the mechanical pump seems to be giving them 5 PSI. Originally, I planned to use the FPR with an electric pump installed after the tank and a return line just coming out of the third carb to keep the fuel lines cool in traffic. Will the FPR mess with the mechanical pump? I imagine the mechanical pump will push fuel regardless based on RPM, but if the FPR is restricting flow right after it, then how will the pump respond? One day I'll be able to post simple updates, but for now it seems all I've got is questions and more questions, so if you've made it this far then sorry, and thanks! As always any help is really appreciated.

Hey Rudi! Sorry, I only just saw this post - not sure if it's helpful anymore but here's the fuse box I installed: https://au.mouser.com/ProductDetail/Littelfuse/04980933X?qs=sGAEpiMZZMvShe%2BZiYheii%2FeEXsvxFUx9RjL22D3SL0%3D&countrycode=AU&currencycode=AUD And here is the rest of the order I made at the same time with the part numbers for the fuses:

Cheers for the suggestions guys. Spoke to the guys at Recarb today (super helpful folks, great to deal with) and they'll be able to send a cable clamp that should work with their linkage arms better than the generic one I've got in there now. Hopefully that'll give good results, but if not then I'll definitely be getting a donor linkage and adapting to suit.

Perhaps it's a 260 thing then, but I couldn't see any solution with the original linkages that wouldn't at least involve me cutting this section down (it's just too long as is) and welding the new hex rod to it. Can be done for sure, I just wanted to avoid it if possible so I can easily revert back if I ever needed to for some reason?

I already had a throttle cable conversion kit with a bunch of cable ends, so I thought I'd try and get that working to avoid cutting up and modifying the original linkage and getting it to work with the new set up, just in case I needed it in its original state one day...

Well, I've finally gone and got some new carbs as per pretty much everyone's recomendation. I ended up going with the Weber 45 DCOE carb / manifold / linkage kit from Recarb and hopefully will be able to get them running tomorrow. Just wondering - does anyone have a solid way they've attached a throttle cable to these carbs? The linkage uses a hex rod, so I can't find a pulley that mounts straight to that hex rod (like how the Kameari / Haradi set up works), and I'm not sure whether I want to be attaching a pulley / bell crank to the centre carb that then somehow actuates the other carbs (seems like that would be inviting unevenness actuating one carb first instead of actuating the whole hex rod from a seperate arm?), or whether there's some other option I'm missing?

Hi Peter, I've somehow got 3 of these N36 intakes, if you're happy to pay for shipping from Wagga then one of them is all yours. Will you be using the cooling / heating line that run through the bottom of them? The one intake not attached to carbs has the line ends rusted out.

Damn, I'd suspected that. A couple of mates have said it'll smoke a lot if it's been sitting and not driven for a long time, so I was hoping that was that case instead. I also had someone suggest valve seals need to be replaced. I talked to a local mechanic today that can tackle an engine rebuild if necessary, I'll most likely end up going down that route. I don't suppose there's a reliably better-than-OEM set of rings for an L28 that anyone could link me to? No idea whether the engine has standard size pistons or not so I guess I'll need to figure that out first. The little cylindrical guys behind a single screw on the left of the carb near the float window? I did find and check them! One had a hole in it so I stole a filter from the spare set of carbs. Cheers for this! Looks more detailed than the Haynes manual I've been going off. I did add choke cables as well for the first time after going off the carbs so I wonder if I've set them up wrong and that's causing the high idle. Will report back...

So it's been a while and I've done a handful of things, and thought I'd update while trying to work out what to do next. I was hoping the work I had done would make a big difference but I don't think that's quite the case, which is honestly a bit of a bummer but not surprising. I've also cleaned and painted a bunch of parts to try and generally freshen up the engine bay, although not to factory standard or style by a long stretch (sorry!). Firstly I sent off the distributor for testing and overhaul. It came back no fault found but with the vacuum mechanism replaced. I really just wanted peace of mind and was happy to pay to make sure everything was working properly and setting my timing accurately was relatively possible. I also replaced the spark plug leads while I was at it. I also decided I wanted to make the whole return line system work, but my fuel rail was pretty bent. Instead of just sourcing another one, for some reason I decided to make my own. I bought all the AN fittings, tubing and some of the tooling ( I had access to some tools at work which helped). The result is okay, but after all is said and done I'd probably prefer an original unit perhaps just cleaned and painted to suit. The anodized aluminum line I used easily cracks when bent, and until I fabricate more brackets the whole piece is a bit flimsy almost? It does work and I made sure to leak test the whole thing before fitting it to the car and risking fuel leaking on to the exhaust. It was kind of fun do something new and I feel like I got my head around AN fittings and general line fabrication, so that's something. I'm sure everyone has already realised this, but using proper, well-made tools is an absolute treat compared to using cheap generic / multi-use stuff. Bending and flaring lines with decent tools was actually satisfying! Next up I wanted to pull apart the ol' flat tops to make sure at the least that nothing was stuck or clogged up. Can't say I enjoyed pulling them off the car, but pulling them apart on the bench was fun. I checked the filters for debris, made sure all the orifices were clear by spraying carb cleaner everywhere and checked the power valves weren't blocked. I adjusted the floats to the specs that came with the gasket kit and re-assembled everything. I also "installed" a radiator overflow can - just a couple of clamps bolted to rivnuts off the radiator for now, sitting where the air flow vent things should probably be. I also figured I should re-install an electric pump to push fuel through the return line like from factory. Because I'd converted to an internally regulated alternator, I ended up also installing an inertia switch behind the center console, to make sure the pump, if connected, would shut off in the event of a collision. If I want to turn the pump off and kill all chance off it running I can also now just easily unplug the wires at the inertia switch. I'm wondering as well if I should be using a ~4 PSI pump instead of whatever the previous owner found at supercheap... With all this done I fired her up, and fuel started poring out of the carb overflow vents. I connected some hoses to the vents, led them into a bucket and began trying to figure out what I'd done wrong. I eventually ended up whacking the bottom of the carbs, hoping the floats had just become stuck, and somehow that seemed to fix it. I've run it a few times since, trying to dial in a rough tune, but can no longer get the car to idle under 1500rpms. I remember it idling lower before I pulled off the carbs, so I must have done something, but don't have a clue what. Last weekend I went around the engine bay and tightened all the screws I'd touched to make sure there were no obvious vacuum leaks, and then ran the car while I had a hose with one end to my ear and the other going around the engine bay trying to find a leak. I couldn't find anything, and now am at a loss as to why the car won't idle below 1500 no matter what I do. The slow idle speed adjustment screw does borderline nothing, and adjusting the timing, fast idle and balance only increases the rpms. If I adjust too far in the wrong direction fuel starts slowly leaking out of the front carb as well. Because I can't figure this out I haven't run it for more than maybe 10 minutes, so I don't know if my return line has helped my suspected fuel line overheating either. It also smokes a lot all of the time (blue-ish mostly, sometimes black when revving) and the exhaust has such a strong smell (although only sometimes despite not changing much between runs?). I was hoping to be able to test drive around the neighborhood by now, but don't feel confident driving it around until it seems to be running better. At this point I'm pretty tempted to take the car to a local 'old school' mechanic and get a professional opinion - if the rings are cracked or the head gasket needs replacing I don't think I'd ever be able to confidently diagnose that myself. I've got valve stem seals, a sump gasket and wheels bearings I'd be happy to pay a mechanic to install as well if they think they're necessary. I was also toying with the idea of either installing the other set of flat tops I have to see if that helps, or going a bit over the top and just buying the ztherapy round top conversion kit. I've just landed a new job so I won't have much spare time for the foreseeable future, so the whole 'throw money at the problem' approach is more attractive than ever. If anyone has any other ideas I'm again all ears! Thanks for reading!

I've had this bookmarked for a while but haven't pulled the trigger yet so I can't speak to quality or fitment (or roadworthiness of using fibreglass?), but these guys are located on the gold coast so could be an option to keep in mind? They also offer a hinged version it seems. https://www.motorsportfibreglass.com.au/products/60/Pin-On-Hatch

Thanks gilltech, I'll definitely try removing the electric pump again if I can't find a way to make it work. I went to all the effort of making the return line system work because the car was vapor locking without it (I think anyway), and i read the electric pump helps to keep the fuel flowing through the system properly. The vapor lock supposedly is mostly prevalent with the flat top carbs and because I've already had that issue and didn't want to swap out the carbs unless I really have to, I want to do everything I can to prevent it from being an issue, hence wanting to get the electric pump to work.

Hi Folks, I'm not certain but I think I've once again got myself into a world of hurt! In trying to generally improve my 1975 260z recently I've done a whole number of modifications, swapping out everything that seemed unreliable and in poor condition - I've changed the alternator to an internally regulated unit (https://zcardepot.com/products/alternator-internal-regulator-280z-280zx-78-80?_pos=8&_sid=d1b3c80bb&_ss=r), following a guide (https://www.atlanticz.ca/zclub/techtips/alternatorswap/index.html), mostly because the voltage regulator was rusted with corroding wires, and I wanted to get a new alternator anyway. I have a feeling some of this new wiring or bypassing of the voltage regulator is causing my problem, but I don't think I can quite work out how to fix it on my own. So - I've made up my own fuel return rail and installed an electric pump in the rear of the car as I figured more fuel movement might require both pumps and not just the mechanical one. The pump isn't factory and wasn't used because I didn't have return lines before, but as I've decided to use the return line in hopes of curing the vapor lock on the flat top carbs, I've installed the electric fuel pump and plugged the wires back in. The car's not ready to start up yet, but as I've just recently reinstalled a lot of overhauled parts I was curious to see if the wiring seemed to hold up. I turned the key to the 'ON' position and got a huge fright when the fuel pump started up, which I've read it isn't supposed to unless the car is running at over 400 rpm (please correct me if I'm wrong). I think my question then is; what have I bypassed to make the electric pump run even in the 'ON' position? Or, if it's not possible to easily run the electric pump safely with an internally regulated alternator, would the mechanical pump suffice even when running a return line? Thanks again for the help! Ben

It was a new eBay piece I installed maybe a year to a year and a half ago? I had no radiator before that, and I myself have never put anything other than garden tap water through it. I even flushed the radiator a few weeks ago when I had it out to replace those clutch fan grub screws. I've known the whole system needs a proper flush but figured I'd do one after it's rego'ed - then I could add in a proper cleaner and drive it around to cycle the cleaner instead of just push it through once. So I've just reverse flushed the engine as recommended. Put the thermostat cover back on with no thermostat inside, disconnected the top radiator hose at the radiator side, disconnected the bottom radiator hose at the radiator side, and then used the garden hose with one of those Bunnings trigger handles to seal it against the top hose and push water through. Did the same with the radiator, only connected the top hose back to the radiator and pushed water through that way. Both now run completely clear water flushes. Both engine and radiator flushes pushed out maybe 6-8 4L buckets of rusty water. Ididn't see any gunk or debris come out of the engine at all, and couldn't spot any leaks anywhere. The water seemed to flow through as it should, I think? No pressure build up up top, just all came out through the bottom hose as far as I can tell. The radiator was more or less the same, but with a few tiny pieces of film, almost? You can barely see them in the pic. What do you guys reckon I should try next? I've confirmed the thermostat works with boiling water again (which I did as well before installing it), which is why I'm so confused about the whole thing. If the thermostat works, and the engine heats up, why isn't the top radiator hose heating up radiator side after the car's been idling for half an hour? Should I idle it with no thermostat and then kill the engine if I can confirm the top of the radiator heats up, just to confirm water circulates the whole system properly? Or switch back to the thermostat with no jiggler pin? Again, thanks heaps for the help! I love that you spotted this straight away. I didn't realise until I got the door cards back from the upholsterer (after a year of waiting) and went to put all the fittings on. It just never crossed my mind that someone would swap out a door with a different year model door. I was pretty disappointed with the door cards though, so I just installed wellnuts in the wrong door to get all the fittings on. Kinda dodgy, but for now I have functioning arm rests and occasionally functioning locks etc. When I can afford to source the right door and buy respectable door cards I will though for sure!