Thoughts about installing carbs on an na2j?

[chatapokai]

While putting together the 2j for the s30 I thought about how cool this thing would sound with ITBs or carbs....and then really started thinking about the possibilities:

 

ITBs would be really cool but I would need an aftermarket ECU (~$1000+$300 for tuning) and the ITBs themselves ($2000 from EFI). Awesome but 3k on top of what the 2j swap and s30 upgrades will cost is a lot (not counting what an aftermarket loom would cost).

 

But what about carbs?

 

I've seen people carb RBs and LSs before, so why not a 2j? So I did some digging and research. Looks like it's not uncommon for people to delete the efi/ecu from some builds for a carb.

 

1. I can fab the intake manifold (~$250-$300) from a very good fabricator near me) to hold the carburetors (free from a friend)

2. The s30 gas tank can be reused and hooked up to an electronic low pressure fuel pump (~3-5psi) and then hooked to the carbs

3. The 2j has a distributor, but it hooks up to the ECU. I would need to find a way to replace the electronic advance (maybe an msd box? Some sort of ignition control is needed).

4. The starter, alternator, pump and ignition could would hook up to the battery.

 

Outside of tuning the carbs it seems doable and I would honestly be much happier with this build as it's much more representative of the 70s. It's the exact build I had in mind.

 

I found an example of this being done: https://engineswapdepot.com/?p=8336

Looks like they used a cam trigger and Ford EDIS but I was hoping to reuse the distributor if I go forward with this.

 

Thoughts? Ideas? Comments? I'm really hoping this is feasible but the ignition seems to be my only stopping point. 

 

[jonbill]

why not leave the ECU running the distributor? 

[NewZed]

Wouldn't the ECU need a MAP sensor for vacuum advance of timing?  Also, an RPM signal for centripetal advance.  Does the 2J use a crank mounted sensor or does it use the distributor type CAS?

 

Interesting idea.  Might be easier to just modify a distributor that has vacuum and mechanical advance to work in the engine, to trigger an electronic ignition.  Timing control is the hard part.

 

 

[chatapokai]

The ecu would indeed need the map sensor etc to run and would throw a code as the efi would not be connected likely running on limp mode.

 

Im 98% sure it is a distributor type cas.

 

The timing is my only stopping point. I believe I'll be able to at least get it to idle with the stock dist. Right now I'm still cleaning up the motor but i think I'll be getting a trio of chinese 40mm idf carbs or 6x 40mm honda bike carbs and trying it out. If it cranks over and runs then I might move on to trying to modify a distributor, or getting a timing control box.

 

Problem is that I have no idea where to get one or how to hook it up. I assume its a box i can wire to the stock dist and vacuum lines and program. Maybe msd has a solution? I know the 4age guys can use another model distributor but I don't think i have that option. 

 

I've seen one other person try it, but they hooked up a crank trigger wheel to a timing control box (megajolt?) and a ford v6 edis system. Maybe that'll be my last resort bc i really really want to do this.

 

 

[chatapokai]

Update: did some research and I think I'm going to try a Toyota 5mge distributor before trying the crank trigger/megajolt solution. It has a vacuum advance, the firing order is the same, and the gear size looks pretty close to the stock 2j dizzy. I might be able to make it fit with minor modification. Worth the $40 for trying. 

 

I'm also heavily researching carbs. My 2 options are modifying Honda or minkuni bike carbs or getting 3x empi vw 40idfs. It'll depend on whether the dizzy fits.

Edited June 10, 2020 by chatapokai

[seattlejester]

For cheap ITB's the GSX-R throttle bodies were pretty popular in the Honda crowd. They come in groups of 4, but are repeating so you could modify as needed.

 

Some carbs on a 2J would be neat, a lot of effort for not much power, but would be a fun project. 6 SU carbs with velocity stacks would look real neat, but you probably could make do with less. If you have a 2jzge the lower intake runner would be an excellent starting place, some custom adapters and you would be in business. Probably run a thinner head gasket or shave the head and run a bigger cam, might see bit over 200hp to the wheels. Keep in mind depending on the motor that may put you into interference territory if you were not before. Probably one of the few times a 2jz-ge VVTI setup would be preferential, granted then you have a VVTI you would have to lock or remove altogether just for the higher compression. 

 

Interesting for sure, keep us updated!

[chatapokai]

@seattlejester So I've decided to pursue the carb route. I still have a month left of grad school but I have started tearing the 260z apart and rebuilding the 2j when I can. I just removed all the accessories and am about to crack open the head and pan to see the condition of the cylinder walls and rod bearings. 

 

I'm 90% leaning towards the VW/Porsche 40IDF carbs and cutting a rectangle down the driver side of the hood so the stacks peek through. Should look and sound pretty cool. 

 

As for the ignition. I found a company that makes dizzys that can be programmed via bluetooth. I think I'm going to send them what I have and see what they can do. I hope it works because I really dont want to deal with a crank trigger wheel and an ignition box. 

[seattlejester]

Most excellent! Should have a cool sound, side drafts on an inline 6 have a really nice induction noise.

 

I would run a compression test to before taking the head off to see if there are any problem areas that may need additional scrutiny. Make sure you buy the 10 point socket for the head and clear out the bolt heads of any gunk, these strip very easily. There is also a technique to removing them that leads to less breakage that I would try and find.

 

If you do have to go a different route, the crank trigger wheel isn't too bad. A 1JZ crank pulley has 4 centered holes that can be used to bolt a DIYautotune wheel to. 

 

You will run into the whole seal preference thing. I'd be tempted to just take the mainstream advice and go with OEM seals when the time comes.

[chatapokai]

@seattlejester super helpful and I'm glad you didnt talk me out of it.

 

Update: I've been slowly gathering the parts needed to swap to carbs. Just finished grad school so I can finally jump into this more. The following is what I've done to this point:

 

• Removed L26 and started cleaning up the engine bay (removing surface rust and will start painting the bay)
• Started rebuilding the 2jz. The head is almost off and I will be doing the following
  • Cold compression test got me values from 135-150 so it seems ok considering the motor was not hot and expanded according to some na-T supra/sc300 friends I have
  • Changing every gasket possible. Going to buy an OEM gasket kit and swap everything out (head/front and rear main seals/valve cover, stem seals, etc) I'm not out for power so OEM will be ok.
  • Water pump and alternator will be changed, not sure about oil pump yet. 
  • Will be upgrading to ARP studs since I liked them so much on my mr2
  • Might get a solid crank pulley instead of reusing the harmonic balancer (unsure)
  • EGR deleted, with 9/16th expansion plug
• Purchased a set of 6 GSXR carbs and manifold to bolt them to the head (They look so good https://www.instagram.com/p/CFvE_cbnlXe/?igshid=dv6y0l5nxurb)
• Sold the AR5 for a nice profit and got a cheap w58 trans. I can now use a stock sc300 slave and clutch to run the car
• Bought an interrupter style motorcycle fuel pump so I dont have to run a return line back to the tank (so glad the carbs only need 4psi to run)
• Talking with123ignition to see if I can get a programmable alternator

 

Next Steps once the engine is built up and bay is painted:

• Install the apexengineered subframe
• Going to get the universal wiring harness from zcardepot (https://zcardepot.com/products/wiring-harness-universal-240z-260z-280z-510) and I will be splicing the 2jz accessories to it (hope that works, Im assuming splicing the 2jz alternator, starter, ignition coil, bike pump, etc to the new s30 harness should work???)
• Find a 2jz to W58 bellhousing somewhere....then ill be able to measure for the trans mount

I'll stop there but I'm pretty happy. So far it looks like splicing that universal harness will be my best bet for keeping it simple while still upgrading to a modern fusebox. 

 

[seattlejester]

OEM seals are used on 1000hp builds so power level isn't much of a concern.

 

Interesting point with the trans, you are running less weight and not much power so a W58 may be perfectly fine.

 

If you do oil pump, worth looking into modified ones with front seal retainers. I did a whole write up on the FMS, differences between the seals and how I think it should be installed, but everyone has their own opinion.

 

Also make sure to run good crank case venting. You won't have the normal problem with pressurizing the crank case, but you will have the problem of not having much of a vacuum source unless you can tie all the runners together.

 

Ooh does danst make a conversion manifold?

 

I think this would honestly be inline with my next build now that I've more or less scratched the turbo monkey. I'd hope for something fairly high compression, maybe even keep the VVTI, and throw in some balancing and try and run the motor a bit more towards higher RPM. That would probably involve crank cradle and all sorts of balancing, but one can dream.

 

Would love to see how you get along. Keep us updated!

[Zetsaz]

10 hours ago, seattlejester said:

 

I think this would honestly be inline with my next build now that I've more or less scratched the turbo monkey. I'd hope for something fairly high compression, maybe even keep the VVTI, and throw in some balancing and try and run the motor a bit more towards higher RPM. That would probably involve crank cradle and all sorts of balancing, but one can dream.

 

Would love to see how you get along. Keep us updated!

 

What you want is Kazuaki Kadowaki's build. It's so goooood.

 

 

He was in an accident that totalled the car a few years back, but I've been following his progress on Instagram for a long time and it's coming back better than ever. 

You'd be able to understand some of his posts far better than I can, but I enjoy seeing his progress pics.

https://www.instagram.com/kazuakikadowaki/

[seattlejester]

I forgot that car existed! Granted I think I like the sound of sidedrafts over ITB's.

[Zetsaz]

1 hour ago, seattlejester said:

I forgot that car existed! Granted I think I like the sound of sidedrafts over ITB's.

 

Yeah we've talked about the side drafts vs ITBs haha. Huge horsepower JZ engines are all the rage, but it's nice to see more out of the box stuff like this being more seriously considered. I think a lot of people get too caught up in numbers games and often don't even finish their builds or lose sight of the fact that modest engines with fewer issues and less $$$ can be so fun.

 

Keep updates coming on the progress Chatapokai! excited to see it.

[chatapokai]

@Zetsaz Exactly. I just want to use my one of my favorite engines in one of my favorite cars and keep it period correct. With light mods I think this will sound very similar to a rebello 3L so I'm excited. I really dont care what the hp numbers will be cause even if I get stock power it'll be punchy.

 

@seattlejester Yea I've been seeing that the W58 is glass after 350hp which I wont be around so I think it's a good middle ground. Just wish I could confirm whether the mounting points are the same as the r154. The mounting point for the trans is what I'm trying to figure out. On your other point, yea I got a manifold from danst, I'll have to drill and attach a hose to each of the pipes and connect them to some summit racing vacuum reservoir so I can hook the crank case, catch can, and brake booster to a single vacuum line. I may have someone make me a .5inch spacer I can put in between the manifold and the head so I can thread hosetails to them.

 

Update: So I'm waiting for tax returns to send the head for machining and to get the main and rod bearings so I can paint and slap everything together. In the meanwhile, I've been de-rusting the engine bay and researching the electrical portion of the carb-swap. Just trying to map out the electrics cause even though it's simplified, I just want to make sure everything is correct especially since I only got pieces of a loom in a box when I bought the 260z shell. This is what I've found so far.

 

Because the stock 2jz dizzy has magnetic pickups and is locked out from factory, I can use a programmable MSD box for ignition timing (programmable 6AL 2). I can use the pickups to one side of the box and the other gets hooked up to an ignition coil and battery. It's not cheap ($400-500), but I will be able to program a full ignition map and get idle and rev limits. I'm glad there's a relatively easy solution to ignition.

 

I need to figure out how to hook up the stock 2jz alternator (which I cannot find? I think I might have lost it....). So I'll eventually have to buy another one and figure out the wiring situation. So far I'm assuming I can cut off and use the connector from the old supra/sc300 harness and splice it to where it needs to go. So far I know the connector gets spliced into the dash (ignition, sensing, and lamp?) and then the one with the bolt gets hooked to the starter. My concern is that I dont think I have the original 260z wiring harness so I have to figure out the complete wiring of the alternator and starter to the dash (which I have 2, one from the 260 and one from a 280).

 

In the meanwhile I'll just keep de-rusting when it's not freezing out. I could use a space heater haha.

Edited December 31, 2020 by chatapokai

[seattlejester]

What mounting points are you looking at, transmission crossmember? They are different on the mk3 supras which would lean to them not lining up great. If your post 73, it won't matter anyway if your going for the r154 it won't fit without removing the stock mounting points unless you plan on having the motor shoved forward and the trans hanging low.

 

Might look at megajolt or something at that price range. Putting in a wheel to read and a sensor for pickup and you won't be limited to the stock 2jz coil architecture. 

 

I know I have the wiring most likely posted on here somewhere as I did the alternator wiring a few times granted 240z on my end so not 1:1, but it could at least decode the alternator on the 2jz side.

[chatapokai]

I would love to reuse the trans mounts and not cut them off. CX racing looks like it has an r154 mount that utilizes the s30 mounts which I like and might buy:

 

https://www.cxracing.com/engine-swap-kit/engine-swap-kit-nissan-datsun/engine-swap-kit-nissan-datsun-240z-260z-280z-s30/TM-R154-240Z

 

according to a facebook 2jz swap page, the r154 and w58 use the same mounting areas, so worst comes to worst I might have to extend the mount but it look like my best bet since I'm not a welder.

 

Yea I looked at the megajolt. I guess I'll figure out what I want to do once the motor is actually installed. Both the megajolt and msd are good options, guess it'll come down to what I plan for the future.

 

I'm sure googleing your handle + the keywords will get me to the thread, I'll check it out! I found a universal loom that I can hook everything else up to, so just the alternator/starter wiring is left.

 

I'll update the thread once I get my engine back from the machine shop and I start putting it together. I cant wait to hear this thing run.

 

 

 

[seattlejester]

FYI the CX engine mount kit for the 2jz  was pretty bad if your going that route, it offsets the whole drivetrain a couple inches, had to make a lot of modification to center it. That trans mount looks kind of similar to what I ran, but I imagine it will hang a bit lower.

 

I think I have my old R154 mount somewhere, granted I put my engine back to within touching distance of the firewall and it was for an earlier 71-72 240z. I know I mimicked the mounts off of someone with a 73, and he had to fully remove the trans mount subframe from his car to mount his transmission. This is of course with mounting the engine back and the trans a bit high, one of my goals was to not have to crab over speed bumps so tucking the trans and exhaust was a requirement. If you don't mind them hanging low it shouldn't be a real problem.

 

[chatapokai]

I plan on being somewhat low, so I definitely don't want anything hanging. I'm using (and already have) the ApexEngineered front subframe and JZ mounts which sit up pretty high and close to the firewall.

 

My two options are to use that cx racing mount which would probably need a spacer/sandwich plate to raise up the w58 mount. But I think I'm going to stay away from cx racing because of your experience and others which have said the same thing. So thanks for the heads up.

 

So instead I'm considering buying the ApexEngineered T56/CD009/RB25 mount and drill it out to accept the W58 mount.

 

https://www.apexengineered.com/store/p27/RB25_%2F_T56_%2F_CD009_Transmission_Mount.html

 

It looks like it mounts to the floor instead of the OEM trans mounts which could help with mounting the trans in the correct position without using an "offset arc". This may be my best option and I can attest to the quality of their materials. It's also cheaper than the cx racing version. Any thoughts? I think this solves both the height and the depth concern if I can get the mount to fit.

 

 

Edited January 30, 2021 by chatapokai

[seattlejester]

It would be the least amount of work from the looks of things, and in theory just an adapter or something to the w58 should work if the mounts are different. 

 

I would personally try and find a local welder. It would take a couple hours for you to clean the area and cut out the pieces with an angle grinder, but you could get the fitment how you want it and the material cost in overkill 3/16 to be safe should be about $20. Granted if you aren't comfortable or familiar the apex piece looks like it should work fine. I guess it depends on how much your time is worth.

 

Curious, how are the carbs going to mount to the head?

[chatapokai]

@seattlejester So it looks like my best choices are between modifying the apexeng mount and getting ome custom made. 

 

I actually talked to an s30 fabricator on instagram. He says he could make me a perfect "lazer-measured" fit mount for it for around 4-500. While that's pricey, it might be worth the peace of mind. I guess we'll sre when it's time. I do, however, like that the apex mount supports the floor too.

 

Anyway, i got a manifold made from danst as well (pic attached). Was going to have a local guy make it, but I think a manifold from the source was worth it for the extra 100 it cost me. 

 

I will need to either tap each tube and thread a hosetail to each for vacuum so I can run a line to the brake booster, charcoal canister, and maybe a catch can.