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Relentless - 1977 280z LS (5.3l L59) swap

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38 minutes ago, Phantom said:

Really nice thread.  Ties in with the work Grenade300 did with his write-up on a '73 240Z.  Thanks for the details on the intake.  I've been considering changing mine over to a cold air intake for a while.


Thanks Phantom, you were one of the main reasons I went with JCI's kit since you had such great things to say and it's stood the test of time so far. 


I'll update with an Air Filter part number soon that fits well, just sort dinking around on the Z while I wait for JCI's new 1-3/4" headers to be made. 

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Slow progress lately, waiting on JCI's new headers to be made.  He made a prototype 1-3/4" design and once it passes fitment they should be on the way.


Wiring is nearly complete (made a fuse block holder, still have to figure out the fusible link situation...)




ODB2 Port is installed under passenger dash.



Reverse Lockout Switch and Check engine LED installed on center console. 



Throttle Cable installed, with custom bracket.

(Bought a 48" Lokar LS1 cable, and cut it length works great with stock pedal assembly)






Lower Radiator Hose installed without any modification (thanks to EastTnZ's build for the part#) 

(This hose will fit -> Truck water pump + stock replacement radiator)

Part# - Gates 22478


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On 7/15/2019 at 7:10 PM, Box5 said:

I'll update with an Air Filter part number soon that fits well, just sort dinking around on the Z while I wait for JCI's new 1-3/4" headers to be made. 

Dang - JCI is doing  1 3/4" headers?  Mine are  1 1/2".  Still have 2 1/2" collectors?

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On 7/16/2019 at 7:08 PM, Phantom said:

Dang - JCI is doing  1 3/4" headers?  Mine are  1/2".  Still have 2 1/2" collectors?


I'm not sure about collector size yet, hopefully 2-1/2".  I'll ask more questions next time, it would be nice if the collector is in the same spot for guys with older headers to upgrade easily.


This weekend my plan is to work out a maxifuse setup to delete the fusible links, and how to delete the voltage regulator, as well as find a good run/start hot wire, the little stuff i've been delaying, maybe bleed the clutch as well. 

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On 7/19/2019 at 12:54 PM, Whitley_280z_2+2 said:

I'm waiting on the JCI headers also...hopefully they don't take him that much longer. This is a great resource for getting rid of the fuesible links: http://www.atlanticz.ca/zclub/techtips/fusiblelinks/index.html 


Nice build!


Thanks, I saw a similar how to before but that one is much clearer.  Sounds like we'll be guinea pigs for header fitment, lots of posts about JTR headers burning spark plug wires with the 1-3/4" primaries, hopefully these avoid that problem without needing special wires and heat shields. 

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  • 3 weeks later...
On 8/16/2019 at 8:16 AM, DonH said:

How much are the headers and hows the fitment? I went with the CX racing engine mounts and trans mount but I feel the CX headers sit WAY to low... 


Lowest point of the new JCI header is flush with the bottom of the camaro oil pan (some inches higher than the frame rails). 

They're $425 shipped now.  


As for fitment, only issue so far is #3 plug wire.  The sparkplug exits nearly pointing at the primary, so the plug wire boot has to bend into position and ends up smashed against the header.  A 90 degree high temp plug wire might work, i'm not sure right now.  I'm gonna fully mount it and see if I can remove the spark plug tonight.




At the correct height to connect to the spark plug the boot hits the tube pretty well. 



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Slow going, waiting on a header fix.  Bought a low pro Accel boot but the dent required would have been too big for my liking.  Hopefully getting a 1.5" set of headers.


Bought a 12" Spal 30102038 Fan to run alongside the generic one that came with the Champion Radiator, had to cut out the shroud for the bigger fan but it mounted fine, hopefully can run it off the 30amp relay I have, we'll see.









JCI Oil Pressure Sensor adapter (attaches to oil pan on drivers side)




JCI Coolant Temp sensor bushing (replaces freeze plug on Drivers side of block)




Both of them installed



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On 10/16/2019 at 8:16 AM, DonH said:

those look great man! Curious if you have come up with a solution to the header issue. it seems amlost EVERY single LS swap header has this issue except the stock headers. Im contemplating keeping stock headers at this point lol 


JCI is sending his original 1.5" design once the fabricator finishes, hopefully this week.  The 1.75" set was really nice but needs a drivers side redesign to work well in my opinion.  There's plenty of clearance by the steering shaft to have all spark plugs fit with the 1.75" primaries, but it can't just be a single mandrel 90, the 1st primary would need a bend down then back to join the others, the dent was going to be massive I didn't want to restrict just one port.  1.5's should tide me over since I might do a cam eventually but nothing too crazy yet.


On 10/16/2019 at 7:01 PM, chiefmd said:

Evan where on JCI's site are those parts located. Couldn't locate them.


It's part of his Vital Liquids set.  He'll sell them individually though if you need just an adapter.

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  • 2 weeks later...

Bit of confusion with the header situation from JCI (thought i was getting 1.5's back, but I ended up getting a reworked 1-3/4" set.  You can see the modified first primary to clear a spark plug and boot well (I'll get pics installed with MSD 8.5mm bendable boots tomorrow to show clearances).  Still might dent the drivers side primary closest to the firewall (far right in the pic below), but it should be minimal and if JCI can touch that primary up on future batches these headers should be perfect for LS swaps in 280z's.  






On 10/31/2019 at 10:30 AM, S30forever said:

Awesome progress, keep us updated...

Hopefully LS1 / T56 swap for me in the near future, subscribed!


Thanks I appreciate it.  Good luck with your build, I'll keep an eye out for when you get going on it.

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I received the Tachometer today with a note saying "requires ECM input only," so big thanks to JCI for that.


Also JCI came through with the 1.75" header revision, they look like the ticket now.

Bought MSD 32829 Plug Wires. (narrow, bendable)



Only tight boot clearance is Cylinder 7 (Drivers side Firewall) but there is a small air gap.  I plan to lightly tap a dent for more airflow around the boot, but I believe JCI will revise that on future batches and these headers will be spot on for 280z LS guys.


Cylinder 7



Cylinder 7 close up (small air gap but close) I can bend them away so might not even need a dent.



Next closest boot is Cylinder 1 (Passenger front) but has a healthy air gap and I haven't bent the boot for more yet.



All the rest fit like this with tons of clearance.





Edited by Box5
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