Ben's 75 260z

[ben92]

Hi Guys!

About 5 years ago a saw a 240z in a magazine - I had never seen one before and instantly fell in love. A year or so later at the age of 24 I was in desperate need of a new hobby, but hadn't had any luck finding an already registered Z. Not having much patience, I (irrationally and naively) bought a 1975 260z 2 seater from someone who seemed to buy and sell a lot of these cars. We struck a rather unconventional deal that I thought would work in my favor considering I knew next to nothing about working on cars at the time.

My car had no engine installed when I bought it, but the seller said he'd help my find an engine and all the other missing parts, and using his contacts arrange to have them installed to get the car practically roadworthy over the next month. The car spent perhaps a year with the seller while nothing happened, and then another year or two with a mechanic who helped a great deal. About a year and a half ago I decided to take on the rest of the project myself and had the car delivered to my home, which I definitely should have done from the start (obvious lesson learned).

I've spent the last year and half chipping away at eventually getting the car rego'd, but not having a properly running and wired car with everything correctly installed to start with has made it a tricky process.

I have however managed to get a bit done. For better or worse I've sanded and painted the tunnel and floor pans in POR15, fixed up the dash and re-upholstered the seats. I had a local fix up the door cards but they ended up disappointing a fair bit, but will get the job done for now. I also changed the headers and installed the rest of the exhaust system, but this will need to be adjusted by a professional in the future as it has some pretty unpleasant notes I think are from it not being fitted and held in place well enough. I also cleaned up / painted the rear tail light housings, and just figured out how to get nearly all of the indicators and lights working as they should be. With the help of co-workers the car slowly fires up now when the battery is well-charged, but I've hit a few roadblocks which will need a seperate topic on the electrical page haha.

 

I haven't been able to actually take the car out for a test drive, and honestly I'm not sure what the best way to safely test an unregistered car is?

Short term goals are really just getting the car rego'd and enjoying it, and then focusing on suspension when I can afford wheels / coilovers / bushings etc. Long term I'd like to paint it and make it look like how I'd like, and even though I can't imagine ever selling the car, I can't imagine ever cutting up the body or doing anything that can be easily reversed.

Anyhow, thanks in advance for all the help and I look forward to eventually getting the car rego'd and going on a drive with some of you one day!

 

Ben

[AndBir]

On 10/10/2020 at 4:23 PM, ben92 said:

has some pretty unpleasant notes I think are from it not being fitted and held in place well enough

Great progress, small measured and well executed steps are best

Unless the flanges on the intake and exhaust manifold are the same thickness then it will be hard to get a good seal.

[ben92]

Apologies in advance for the long post, but I think I need some direction! Thought I'd update my thread instead of make a bunch of different new topics.

So I've made small bits of progress over the last couple of months, mostly easy stuff I thought would help get her running a bit better. I was going to try and attempt to tune the flat top carbs with the Haynes manual today, but took a video to see exactly how much smoke there is. I'm not sure but it seems to be a fair bit worse than I thought it was, a week ago I would have said there was only blue smoke on deceleration but the video shows otherwise. Recently I've:

-cleaned up the fusible link setup, all seems to be 'working' the same after the change

-switched the alternator to an internally regulated unit after I realized my voltage regulator was blowing fuses when plugged in. I had it running today both with jumped wires and without in place of the voltage regulator connections, but haven't managed to get a diode yet so the car doesn't shut off when the wires are jumped. 

-swapped the jiggler-free thermostat I put in with a thermostat that does have a jiggler, because I didn't think the car was getting up to temp with the jiggler removed (too much cool water circulating through the whole system + a larger than stock radiator?). Originally I removed the jiggler because I don't have coolant lines running through my carbs and back into the thermostat. The temp / oil gauge previously worked in the key 'on' position but turned off when the car was actually running. As of today I don't think the gauge works at all. I've got a radiator cap that's also a temp gauge but I figure this won't be accurate because the water only circulates back through the radiator after reaching running temp, right? (There's no water / coolant  at the very top of the radiator - should there be, or should it only flow through the top right below the cap when it's at operating temp? I filled it up to the point where it came out of the overflow, and then drained a little so it didn't spill out anymore)

-installed a new PCV valve

-adjusted valve lash clearances and installed a new valve cover gasket

-cleaned up the wires around the ignition coil - I've got an E12-80 ignition module style distributor and had to do some re-wiring to get the tacho to work.

 

I let the car idle for at least 20 mins this morning, planning to check ignition timing if I could get it to operating temp, and then tune the carbs. Took the video, but then when it started to warm up it started to stutter and slowly die so I switched it off. It would start a little after this and run if I hit the accelerator, but eventually it just wouldn't even start. I haven't really let it idle for long periods before so I don't know whether this is because of something I've done recently or not. It may have been the battery dying because I removed the jumped wires at one point, so perhaps the wiring circuit wasn't charging the battery (complete guess, I just followed the steps right at the bottom of this guide (http://atlanticz.ca/zclub/techtips/alternatorswap/index.html).

The coolant hose between the front top of the engine and the top of the radiator doesn't heat up - the hoses going to and from the cabin do and the valve cover gets hot. The top of the radiator is cold and the radiator cap gauge never increases since changing to the jiggler thermostat - before with the jiggler-free thermostat it got to 60ish degrees after idling for more than half an hour, but never actually to the 80 something degree operating temp as far as I could tell.

So - I can charge the battery and install the correct diode to complete the wiring in place of the voltage regulator, and this may fix the car dying. If it does then I'll check the ignition timing and attempt to tune the carbs. I know it's hard to tell - but should I be checking anything else first with all that smoke coming out of the exhaust? There's a slow oil leak from the oil pan gasket in a few spots, but I don't think that'd be the culprit?

I did have a few other questions that may or may not be related:

- My send fuel line rusted and snapped in the engine bay, so the return line has been used as the send line since I've got the car. How bad is this, and should I be blocking off the snapped send line until I can get it fixed and run the complete return system?

- The emissions line is also just open in the engine bay as I was planning on venting it out somewhere else with a filter on the end, but I'm now wondering if this needs to be part of a closed vacuum system? Should I be fitting a carbon cannister and installing a line to the air box?

- The ebay radiator has an overflow port but I haven't put in a coolant catch can yet. Is the coolant system also supposed to be sealed?

If you can't tell already I have practically no idea what I'm doing and am just figuring all of this stuff out as I go for the first time, so any help at all is really appreciated.

 

 

 

 

[AndBir]

29 minutes ago, ben92 said:

I let the car idle for at least 20 mins this morning, planning to check ignition timing if I could get it to operating temp, and then tune the carbs. Took the video, but then when it started to warm up it started to stutter and slowly die so I switched it off. It would start a little after this and run if I hit the accelerator, but eventually it just wouldn't even start. I haven't really let it idle for long periods before so I don't know whether this is because of something I've done recently or not.

Not an expert (far from it), but looks like it is running too rich and probably eventually fouled the spark plugs.

[gilltech]

I suggest you check the hard fuel line set attached to the engine, that it's all clear and not rusty, and make sure the return line restrictor portion is not blocked.

[Linton]

the fact that the radiator top tank is not getting hot after 5 min let alone 20 is a serious problem, did you put the thermostat in the right way up? maybe your engine is seizing not over fueling I wouldn't run it till you sort this out.... take out thermostat and refit the cover, remove the bottom hose and reverse flush the engine through the bottom hose, water should run out the water pump.. HTH

[ben92]

1 hour ago, AndBir said:

Not an expert (far from it), but looks like it is running too rich and probably eventually fouled the spark plugs.

I think you're right and this is why I wanted to try my hand at tuning the carbs. I've only ran the car a handful of times since putting in a new set of the recommended spark plugs, but the set I took off were all completely fouled and black. Because the Haynes manual says to adjust valve clearances and timing first I've ran the car with the new plugs before attempting to tune, but perhaps it's so rich they're already fouled?

50 minutes ago, gilltech said:

I suggest you check the hard fuel line set attached to the engine, that it's all clear and not rusty, and make sure the return line restrictor portion is not blocked.

I only have rubber fuel line from the mechanical pump attached to the engine (also don't have an electronic pump at the rear), there's a pic I think on my first post. Still, I was worried the return line being a bit narrower than the send might not be helping?

15 minutes ago, Linton said:

the fact that the radiator top tank is not getting hot after 5 min let alone 20 is a serious problem, did you put the thermostat in the right way up? maybe your engine is seizing not over fueling I wouldn't run it till you sort this out.... take out thermostat and refit the cover, remove the bottom hose and reverse flush the engine through the bottom hose, water should run out the water pump.. HTH

Originally when I got the car there was no thermostat and it ran like this the first time it was fired up. The old housing was rusty, so I replaced the housing and cover and put in a thermostat - again I had no idea what I was doing so I made sure to look up the right way to put it in. I would've swore it was the right up, but I've just taken the cover off for peace of mind. Please tell me I haven't managed to somehow put it in upside down thinking it's the right way up? The thermostat I swapped it out with a few weeks ago was more or less the same, just with a 2mm-ish hole where the jiggler is on this one. And more worryingly why do I now have all this nightmarish gunk that wasn't there a few weeks ago?

[gilltech]

Quote

I only have rubber fuel line from the mechanical pump attached to the engine (also don't have an electronic pump at the rear), there's a pic I think on my first post.

Ah, I see now, so no hard lines to carbs just that rubber fuel line, doesn't look the safest. I don't know when the electric fuel pumps came in, my '74 just has the mechanical.

Who installed the alloy radiator and how long ago? I'm thinking it must be well and truly clogged up with crap from the motor and maybe some kind of antifreeze additive that is turning to sludge, if the heated water is unable to travel up to the top tank. Both motor and radiator needs a thorough clean out. Back flushing with the old garden hose might not achieve much despite what some people say but better than nothing. If the radiator is well clogged then take it to a shop to be properly cleaned out. You'll just have to do the best you can in situ with the motor, water pump and hoses.

 

FWIW. Have you noticed that your two door shells are different? I'd say the LH door is off a 240Z, I'm going by the cut-outs and shapings on the inner faces. Be aware that the window winders, positioning and geometry of same, are different, and of course the trim and hardware fixing points are different between 240Z, early 260Z and later 260Z. Swapping doors across the various cars is a whole separate discussion in itself.

Edited January 8, 2021 by gilltech

[Linton]

the engine and radiator will need a good flush, gunk could be oil contamination but more likely it has had an anti freeze or stop leak added to the coolant which has congealed in the system, either way fix this first and worry about the carbies later, the jiggle valve faces the front of the housing, towards the radiator, it is in the right way.

[ben92]

16 hours ago, gilltech said:

Who installed the alloy radiator and how long ago? I'm thinking it must be well and truly clogged up with crap from the motor and maybe some kind of antifreeze additive that is turning to sludge, if the heated water is unable to travel up to the top tank. Both motor and radiator needs a thorough clean out. Back flushing with the old garden hose might not achieve much despite what some people say but better than nothing. If the radiator is well clogged then take it to a shop to be properly cleaned out. You'll just have to do the best you can in situ with the motor, water pump and hoses.

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!

16 hours ago, gilltech said:

FWIW. Have you noticed that your two door shells are different? I'd say the LH door is off a 240Z, I'm going by the cut-outs and shapings on the inner faces. Be aware that the window winders, positioning and geometry of same, are different, and of course the trim and hardware fixing points are different between 240Z, early 260Z and later 260Z. Swapping doors across the various cars is a whole separate discussion in itself.

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!

[gilltech]

Quote

never crossed my mind that someone would swap out a door with a different year model door.

Well as always it's the problem of finding a matching door to the damaged or rusted out one, spare S30 2-seater doors aren't thick on the ground. As I understand it there were at least 5 significant shell variations across the various markets the cars were sold in.

However, there are now repro doors available which is a relief to S30 restorers no doubt. I see that they are advertised on eBay as 240Z/260Z. I just don't know how that works when the mechanism is specific and layout is different on each.

[ben92]

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!

[C.A.R.]

10 hours ago, ben92 said:

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!

Nissan used very soft oil control rings in the pistons.
These wear first causing oil to be sucked up into the combustion chamber, hence your blue smoke.
Only way to fix it is to rebuild the engine.

Black smoke is an overly rich mixture from those horrible flat top Hitachi's that you CAN'T tune out.
I suggest fitting 240Z Hitachi's or triple carbs.

[gilltech]

With a flat top carb, I presume you found it but FWIW there is an in-line filter screen just inside after the fuel inlet that can pick up crud and cause erratic idling and partial fuel starvation. Ask me how I know.  

[Enzo]

260Z Carb Adjustment Manual1.pdf

[ben92]

10 hours ago, C.A.F. said:

Nissan used very soft oil control rings in the pistons.
These wear first causing oil to be sucked up into the combustion chamber, hence your blue smoke.
Only way to fix it is to rebuild the engine.

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.

8 hours ago, gilltech said:

With a flat top carb, I presume you found it but FWIW there is an in-line filter screen just inside after the fuel inlet that can pick up crud and cause erratic idling and partial fuel starvation. Ask me how I know.  

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.

7 hours ago, Enzo said:

260Z Carb Adjustment Manual1.pdf 774.29 kB · 8 downloads

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...

[ben92]

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? 

[C.A.R.]

Why have you converted to a cable?

There's nothing wrong with the standard linkage rods...

[ben92]

1 hour ago, C.A.R. said:

Why have you converted to a cable?

There's nothing wrong with the standard linkage rods...

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...

[AndBir]

3 hours ago, ben92 said:

to avoid cutting up and modifying the original linkage and getting it to work with the new set up

When I fitted my triples I did not need to cut up/change any of the original linkages.

[ben92]

1 hour ago, AndBir said:

When I fitted my triples I did not need to cut up/change any of the original linkages.

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?

[AndBir]

Maybe you can adapt the Harada Shokai linkage parts (not hex rod) : 

Even see if you can put one of these on the end of the hex rod : http://www.jcy.co.jp/hrd/m-l6l4-joint.htm

Edited October 31, 2021 by AndBir
added linkage info

[Agno]

15 hours ago, AndBir said:

That linkage thing above is a piece of crap. In the end I threw that junk out, cut the stock linkage to an appropriate length, sleeved and welded it.

You could do exactly the same thing and keep your original linkage by buying a LHD linkage rod and using that as the donor.

[ben92]

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.

[CroS13]

Hey mate great work and upgrades on the car, I like how your modernising everything.

Where did you get the fuse box to replace the fusible link set up?

Rudi.