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nmehdikh

240z with L26 - ITBs, EFI, megasquirt

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Car is a 1973 240z with an L26 basket case, with lots of rust and wiring issues.

Since my initial question thread started getting offtopic, I figured I would finally start a build thread to expand on my questions, and document my progress so far with the car. Original thread is found HERE

Parts are on order and I'm slowly putting together my EFI / ITB setup. I'll post updates and questions here. Since the start of that thread, I've really dug into the car to find terrible rust as expected. So, first order of business was replacing the floors and flame rails. Got floors from zedfindings and rails from baddog.

Passenger side before paint. Driver side painted. You can see the rats nest of wiring hanging under the dash. Going to have to clean this all up pretty soon.
kkfm1i0.jpgg2LT2Xg.jpg

My car didn't have seatbelts when I bought it, so I also put in a half cage and harnesses. Cage was built and welded in by a local shop. My seats currently sit too high for my liking (and for the harnesses), so I'm either going to get new seats or a build a smaller seat bracket.
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Also replaced redid the entire braking system with 4 piston discs in the front, converted the rear to disks, and a new master cylinder.
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I've also replaced most of the suspension bushings, still have a few to do. This weekend I am going to pull the head off to get it rebuilt. Which leads me to my first set of questions.

I thought the car just had a stock L26 in it. But now I'm not too sure so I need some help identifying stuff and how to move forward. The block is stamped "L26 086142" and the head is stamped "N42". I previously did a valve adjustment, and I remember checking the cam markings and it had standard mark but now that I realize it has a N42, I'm not sure if it hasn't been reground. There is a isky racing cams sticker on the car window, but who knows if that is just for "show".

When I pull the head off, how do I go about identifying the cam? And if it has been reground?
How do I check if the head has been shaved?

What should I look for inside the motor (should I expect flat top pistons? Or dished? or notched?)?
Given that I am going megasquirt EFI with ITBs, what should I have done for the head performance wise?
Valve springs?
Cam suggestions?
 

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I would think if the cam was re-ground, there would be extra markings like engraving or stampings at the rear end of the cam.

As for the head thickness you can measure it against stock specs for total thickness.

I believe the stock US L26 pistons were dished but not 100 % sure. At least mine were.

Edited by BJSZED

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Got the head off today, as well as the rad which is being replaced. Everything went fairly smoothly.

This is my first Z, but does this look normal? Flat top pistons in an L26? I thought they were supposed to be dished.
IMG_20171230_161714.thumb.jpg.ab9171f5a0240f7c84349ebb8134389d.jpg
What kind of compression ratio should I be seeing here? Using the atlanticZ calculator (even though its for an L28) with L26 bore and stroke says 9.36:1 with the felpro gasket.

Pics of the valves. Going to talk to california datsun to see if I can take it in later this week.IMG_20171230_162301.thumb.jpg.8c528b1142c60781d458beafe50dfca8.jpgIMG_20171230_162304.thumb.jpg.5700c194549af2692870c259b5a65ef5.jpg

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Posted (edited)

California Datsun is an absolute disaster. Also, N42 head was used on early model 280z. Standard head on the L26 was an E88. 

Edited by Zetsaz
Added info on N42 head.

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7 hours ago, madkaw said:

CALIFORNIA DATSUN😱

 

4 hours ago, grannyknot said:

You might want to check the archives for other members experiences with them before you do that.

 

1 hour ago, Zetsaz said:

California Datsun is an absolute disaster. Also, N42 head was used on early model 280z. Standard head on the L26 was an E88. 


Jesus. I'm so glad I posted here, you all just saved my ass.

Any place you guys recommend instead?

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The N42 is very similar to the late model e88 that’s supposed to be on there . Advantage is that the n42 has the bigger l28 valves and steel seats , so good to go there. I’d call around to machine shops and find one familiar with Datsun heads . You might only need a valve job and maybe a skim cut on the mating surface- which most shops should be able to do . 

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You might want to check out the FAQ page here and look under L6 engines and find many discussions about the different cylinder heads and how to modify them. The info is here- but you’ll need to do your homework

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stumbled across your other thread, im actually slowly putting together a setup with ZX12R ITBs. have the manifold and one set of ITBs, going to start the spacing and mounting shortly and order the second set, no rush though as I am overseas and my car is in a barn so its just a fun basement tinker project. have any pics of the triumph ITBs you are using?

 

one thing i havent seen you discuss, with regard to fuel setup, is that youll want some baffling or, as i'm doing, a surge tank (or fuel cell)

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6 hours ago, ol doc gully said:

stumbled across your other thread, im actually slowly putting together a setup with ZX12R ITBs. have the manifold and one set of ITBs, going to start the spacing and mounting shortly and order the second set, no rush though as I am overseas and my car is in a barn so its just a fun basement tinker project. have any pics of the triumph ITBs you are using?

 

one thing i havent seen you discuss, with regard to fuel setup, is that youll want some baffling or, as i'm doing, a surge tank (or fuel cell)


I got two sets of the triumph street triple R or daytona 675 throttle bodies. Here is one of the ebay listings, it even came with fuel rail and injector if you were inclined to use them, but I'm using a manifold flange from Blake Machine thats already set up for EFI. Seemed like going with two sets of 3 throttle bodies would be easier to work with rather than taking a 4 and splitting it in half.

As far as fuel, I'm going to be pulling the tank in the near future. Once its out I can decide if it's worth saving or if I'm going to go with a fuel cell. If that tank is in good condition, I'm going to weld some baffles in and refinish the whole thing. Tanks Inc makes a drop in fuel pump with a sump around it, but I think I would still like to put in some more baffles or fuel tank foam.

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Looking good. 

 

One way to check if your cam is stock is to measure from the tip of the lobe across to the bottom of the base circle then subtract the diameter across the base circle alone. My guess is that the cam is not stock, based on the n42 head and flattops you've already discovered. 

 

I'm sure someone can pipe up with stock base circle and cam lift numbers for an n42 or l26 e88. 

 

Your seats are awesome, but for track duty, these days having a provision for a HANS device is becoming a no brainer. Second set of seats, maybe? 

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On 1/4/2018 at 7:03 AM, bradyzq said:

Your seats are awesome, but for track duty, these days having a provision for a HANS device is becoming a no brainer. Second set of seats, maybe? 


The seats were in the car when I bought it, and I agree. While they look great and are very comfortable for street driving, I am definitely going to get a dedicated track seat before taking the car out.

I had some free time today so I started CAD-ing up the tubing connections between the intake flange I have and the ITBs. Unfortunately, due to the spacing of the triumph ITBs and the spacing of the intake ports, its damn near impossible to get equal length runners. I need to go talk to some local aluminum tube bending companies and get their input on what's the best way to go about this.

Capture.thumb.PNG.a63a824db0e43826b993b12013968d95.PNG

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You are right about it not needing to be that precise. I CAD-ed them up so I could figure out the spacing of the two sets of ITBs relative to each other, while minimizing the offset of each individual runner. It was to give me a starting point before I start fabbing up the pipework by hand.

Got the gas tank out today. Going to clean it out and make sure all the fumes are out before I cut it open next weekend to install the new fuel pump. New camshaft / head parts should be here Tuesday, then I can take the head in to be rebuilt.

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I had bought a new set of headers from top end performance, I took them in to be ceramic coated, and got the valve cover redone as well. Finished wrapping the header yesterday afternoon. Need to get proper metal ties for the header wrap.
header.thumb.jpg.55c759ee44fd27301dcc66537164ad2d.jpg

 

Also pulled the dash today to start on the wiring and vintage air setup. Long road ahead dealing with this rat's nest from the previous owner.

wiring.thumb.jpg.175fe555a222f46b45ccc1bf2f11ea6a.jpg

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I spent this afternoon in the machine shop making a mount that would let me use existing holes in the triumph throttle bodies. Off of this mount I setup my throttle linkages and idler rod. Here is everything setup with a loose test fit. I still need to work on the sides of the droplink that connect to the triumph cable pull location.IMG_20180202_164745.thumb.jpg.f135b103de5b1d1b4b0a4db4cd63c09e.jpgIMG_20180202_181256.thumb.jpg.ceb220c5c156396e0e25f2f17ada76e6.jpg

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6 hours ago, rossman said:

Is that silicone hose you are using to mount your ITBs to the manifold? I'm pretty sure fuel will break down the silicone.


Yes, its silicone hose, but the fuel injectors are down the line past the hoses and on the manifold flange. Do you think it would still cause problems? Worst case I can always weld it up, the hoses were about $20.

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I'm going to be plugging my old feed, return, and vent holes off the tank and using the stuff from the new pump mount. What are my options for plugging the openings? Are there any fuel safe rubber caps? Or do I have to go with the bolt clamped into a fuel hose method?

My datsun's mysterious history continues to baffle me. Started working on installing the fuel pump in the tank today. Cut open the top, cleaned it up etc. Found these guys rattling around inside the tank. No clue where they came from. Any ideas guys?
IMG_20180129_182459.jpg.e9ea7548e0ed68d8fbf7c5f2b7f7ddb4.jpg

Edited by nmehdikh

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