Manifold Water Circulation

[RestoZ]

Hi All,

Have been doing a bit of work on my SU's and manifolds, zinc plating and passivating various bits and in the process have discovered the connecting pipe which runs between both carbies is rusted out, as is one of the inlet pipes and two core plugs - one in the inlet manifold and one in the emissions manifold (yes, she's a 77 GSR30 2+2, complete with all the emissions gear). The pictures below show the story.

I have a couple of questions:

I read in a recent post (which I can't for the life of me find again) in which someone was querying where things went on the same carby setup as mine. In one of the responses, there was reference to the fact that "noone uses the water connections to the manifold". You can see in the pics below that the water inlet pipe on the right has rusted out in the Inlet Manifold Before pic and if it is not required, I would prefer just to plug it up. Same with the joiner tube between the left and right manifolds as shown in the Carby Manifold and Joiner Tube pic below. I think I read somewhere the purpose of running water through these was to assist with warming of the manifolds, which in Oz isn't really an issue and certainly not in Perth - is that correct?

Secondly, does anyone know where I can get the core plugs in the carby and emissions manifolds. I realise if I'm not running any water, then they probably aren't necessary, but would prefer to block them off if I can. 

As a matter of interest, carby and manifold cleanup was done using soda in the sand blasting cabinet and the zinc plating and gold passivating was done after about 2 months of trial and error with my home plating setup. Will be rerunning a couple of the bits and have some more to do to finish these off, but getting there. 

Cheers

Paul

  

 

[Linton]

hmmm, , to my limited knowledge the 260 had hitachi carbies not SU as for the rest no need to run water. if your car hasn't got all the emission connections on it i would get rid of all that as well,  or better still source another tube without all the pollution stuff on it

[gilltech]

Nice work. Looks like you have SU-style round-tops transplanting the original flat-top carbs (good!), but retaining the 260Z intake manifolds with the emissions gear.

Ditto what Linton says above. You don't really need water circulating through the inlet manifolds and the emissions gear can be dispensed with. It's just more to go wrong with all the extra connections. And you don't need to plug the holes through the manifolds unless you think it looks prettier. Just change the heater hoses to by-pass the circuit round through the carbs and you're good.

On my RS30 early on I had one of the small hoses burst just on Xmas, so I disconnected the water circulation circuit to keep the car mobile and later removed it all completely. The metal pipes were rusty inside on mine too so had to go. No noticeable difference or ill effects and I used to drive my car in all sorts of conditions in NZ, away for winter sports etc. Later I ditched the flat-tops in favour of the 240Z round-tops and better running, although I also used the 240Z manifolds which look a bit 'cleaner' IMO.

So unless you're going concours-d'elegance then keep it simple. (And if you are going concours-d'elegance then you have the wrong carbs for a 260Z anyway and good luck finding the correct Nissan braided hoses and other bits.  )

Edited October 9, 2020 by gilltech

[RestoZ]

Thanks for your responses guys. 

I will have to go through the process of registering the car in WA once it is all finished and I know the inspection boys have been very particular in the past about not making any changes to the emission system. Consequently, think I will have to at least present it all sufficiently intact to get it past that process. Once licensed, I can look at making some changes in that area. If someone in WA thinks this situation has changed (it's been a while since I've been through the process) can you let me know 'cos getting rid of all that plumbing is ultimately where I want to end up.

Fortunately, the core plugs are all located in inconspicuous spots, out of sight, so if I'm not able to source replacements, it's not a major issue, I'll just leave them out. I would prefer to replace them though, so if anyone knows where I might be able to source them, please let me know. 

It's interesting about the carbs. The car has had a few owners in its lifetime, mainly in Qld, so I would say they were swapped over there at some point. The id tag on the right side carby is AUD330R, which appears to come from a 69-71 Rover 2000 TC. Will need to check the jetting to make sure it is correct. Good new is the flat tops have gone and the SU's hopefully will be a bit simpler to manage and the performance a bit better.

No desire to go concours, but I do want to keep it as close to original as possible with a few niceties to make life comfortable when out and about. 

Once again, thanks for your input. I'm new to the Z world and appreciate all the feedback I can get. 

Cheers

Paul

 

 

[AndBir]

46 minutes ago, RestoZ said:

Will need to check the jetting to make sure it is correct.

A good video about the internal workings of an SU carb (although this one is an HIF) : 

 

Also this one : https://www.youtube.com/watch?v=e15QlVLjJiU

 

Edited October 8, 2020 by AndBir

[gilltech]

I suppose if the WA inspectors start comparing your set-up to pictures of what the car would have been sold with originally then you could have a problem, unless you can get some kind of dispensation based on the 240Z round-tops set-up perhaps even though your car is a few years newer. But fingers crossed they won't be that picky! You wouldn't want to have to fit a set of flat-tops along with the matching air cleaner and all the connections just to get the car registered.....

PS. if you can get hold of a 240Z balance tube it's a whole lot 'cleaner' than the 260Z one with all its lumps and bumps and drilled bosses for all the emissions add-ons.

 

Edited October 9, 2020 by gilltech

[RestoZ]

Before I go much further, think I will talk to one of the inspectors and try to find out what they might nail me on. Things have changed in WA over the past couple of years and inspections for new licenses/relicenses are now done by private contractors rather than Department of Transport. Have dealt with DoT previously and they were extremely pedantic an absolute pain the bumb. Hopefully, things are a bit more relaxed these days. 

Will keep an eye out for a 240z balance tube to fit after the car is licensed. I'll be looking at a good set of headers at that point, so will sort the whole thing at once. 

Thanks for the link above AndBir. Really, really good set of videos provided by this guy. He really knows his stuff and the info has been invaluable for a SU first timer. Will be working through the processes he has outlined when I get to that point. 

Thanks for the info guys, much appreciated. 

[Linton]

I'm with gilltech, change the balance tube and say nothing they probably wont notice, but if you talk to them, they will be forced to investigate and come up with stuff you wont like..

[Cozza]

Agree with Linton.

id stay quiet and see if your car passes before asking any questions.

[PB260Z]

as others have suggested don't go looking for problems.

From my experience with private inspectors, albeit in NSW, most inspectors will be looking for things that look out place or missing. Just make sure that there no visible blanked hoses and all vacuum line points have a hose connected to them, even if that hose just disappears into the engine bay and is blocked  

Cheers

PB

[gilltech]

One thing which hasn't been mentioned and I don't see in your photos, is what air cleaner set-up do you have?

[RestoZ]

Good point Gilltech!!!

When I bought the car, it came with one half round foam cleaner on one carby and nothing on the other, so that's going in the bin. 

I am on the lookout for a genuine 260z air cleaner 'cos, as I've said previously, while it won't be concourse, I want to keep it as close to original as possible. 

So, if anyone has one they are wanting to get rid of, let me know.

[RestoZ]

Just a thought, will the original air cleaner from an Oz 260z bolt up to the round top SU's? or am I better off sticking with individual ones for each carb? Secondly, are the elements for the original air cleaner available in Oz? 

[Linton]

the short answer is no it wont bolt up without modifying and yes the original filter is available i got one off ebay way back before the tripples  my new car has su's but a 240z air cleaner

[gilltech]

Just as per Linton's advice above. The 260Z air cleaner (for flat-tops) and 240Z air cleaner (for round-tops) bolt up differently. The 260Z air cleaner is more bulky and has additional fittings for the 260Z emissions gear.

Linton could advise if the 240Z air cleaner is a straight bolt up to British SUs, or if needs minor mods, I haven't tried that combo.

The 260Z unit should be easier to find than a 240Z unit, but you will have to modify it somewhat to suit. FWIW, not all '240Z style' air cleaners are exactly the same, nor necessarily off 240Zs either; I say that because I have one here which looks the same externally but I suspect was originally from a 2L engined Fairlady or 240K or something like that as the internal holes are sized for slightly smaller diameter carbys. But hunt around and see what comes up. As you say it's surely better to install one or other in lieu of a pair of the aftermarket chrome units if you think the inspectors will be looking closely.

Both the 240Z and 260Z air cleaner elements are available, look on eBay, there is a nissandatsunparts supplier who has them, I just got a new 240Z element from him last week.

Edited October 12, 2020 by gilltech

[RestoZ]

Thanks Guys, really appreciate your input. It seems from what you are saying, that it is possible to fit either the 240 or 260 air cleaner, albeit with a bit of modification, which I'm comfortable doing, assuming it involves a bit of cutting, drilling, welding and filling to get the apertures lining up with the carby intakes. 

I'll keep an eye out for suitable air cleaners during the ongoing restoration and see what I can do once I'm able to source one. Off to Datsun in the Park this Sunday in Perth, so will see what others have done to address the issue and perhaps get some idea of what's involved. 

Once again, thanks muchly. 

Paul 

[gilltech]

All the best with your project.