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Barefootdan's 280z Build


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Posted (edited)

Well after spending the past month in the "Help Me!" section, my 1975 280z lives! I figured it is a good time to start a build thread in the proper section to showcase my next steps.

Lets see, where do we start? The story goes that this 1975 280z was an Arizona car for the majority of its life. The owner parked it sometime around 1993 (last registered tags) due to an "ignition issue". It certainly looks the part for sitting nearly 30 years. Odometer says 80k miles, but maybe this is 180k? Looks like it was the silver blue originally then repainted, and finally the fading took over. The engine turned freely and nothing seemed to be seized. It was a clean title and only missing the key, an easy fix.

Towed it home:

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And parked her to start tearing into it:

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The interior was coated in a nice layer of dust, the window was cracked down a few inches...so the weather made its way inside. The ECU was indeed on the chair like that!

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The speedometer was unreadable from the dust! But its all there which was nice.

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These cards will need a full replacement:

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Found some cool discount tire receipts from 1989 🙂 

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And the color it was SUPPOSED to be!
IMG_1448.jpeg

 

 

Edited by Barefootdan
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First order of business was to clean out the interior. I tore out all the panels and carpet to see what we were working with.

🤢

IMG_1494.jpeg

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Drivers footwell has a few holes of rust:

IMG_1512.jpeg

 

But the passenger side got the metal cancer pretty badly:

IMG_1514.jpeg

This will be addressed at a later date, but its nice to see what I am working with.

The trunk wasnt too bad, just some surface rust and that original blue:

IMG_1495.jpeg

 

 

Some cleaning while I waited for parts:

IMG_1496.jpegIMG_1497.jpeg

Maybe the dust acted as a UV Barrier 😂

Dash is out, cracked and crusty. I'll be ordering a new cap soon:

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But for now, some elbow grease is good enough:

IMG_1522.jpeg

 

Misc panels after a nice scrub:

 

IMG_1504.jpeg

 

 

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Next was to see this girl run! Even the engine bay has a nice coating of dust on everything! Luckily the previous owner capped the intake, I think they knew it wasnt going to run for a bit:

63591331932__7E1274D8-993D-4BF5-9D2E-C2843E9543D9.jpeg

Here is the bay after sourcing an AFM, coil, plugs, wires, battery, starter, and some new fuel lines. The oil around the valve cover is from the missing 4 or 5 valve cover bolts! Started to seep as soon as I filled it. It didnt bother me as I knew we would be diving deeper soon.

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This is when I joined the club and started to walk through all the electrical gremlins. @Zed Head was a huge help walking me through the FSM and EFI bible. We encountered numerous loose connections, all 6 injectors were bad, fuel pump needed replacing, redid the fusible links, etc. But we got it running! After nearly 30 years, its back to life:

 

63755326015__79A1EB90-D9D6-4F16-8314-28C58C4BE12C.jpeg

 

Unfortunately cylinder #3 had 0 compression. a valve adjustment yielded no improvement. Maybe this had something to do with that? Found this guy in the trunk. I've never seen this before! 

 

unnamed.jpg

 

 

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So OFF WITH YER HEAD!

Block.jpg

 

Check out that cam bolt. Probably torqued to 30ft-lbs only. Im glad I was able to get it off:

IMG_1674.jpeg

 

We can see #1 and #3 both had some run ins with their valves:

 

Cyl #1.jpg

Cyl #3.jpg

 

The rest of the pistons look...okay?

 

IMG_1688.jpegIMG_1687.jpegIMG_1685.jpegIMG_1689.jpeg

 

I did notice that the numbers on the pistons dont match up with the cylinder count (#3 is in cylinder #1) is that something to worry about?

The head had some gross coolant passages too:

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The valves:

IMG_1679.jpegIMG_1678.jpegIMG_1677.jpegIMG_1676.jpegIMG_1675.jpegIMG_1680.jpeg

 

And of course the trouble makers of #1 and #3 could easily see a flashlight:
IMG_1681.jpegIMG_1682.jpeg

 

And well...that brings us to today. The head is off, and time to decide the build route. I am sticking with the oem efi system for now, so no crazy builds. My thoughts are a stage 1 cam, headers, exhaust, new valves, seals, etc all in the head. Thoughts? Maybe i just stick to a refresh for now?

Then I am debating pulling the pistons to do rings "while im in there". And of course a new timing chain and tensioner/guides to wrap it up.

 

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Posted (edited)

Well there's your problem!!  LOL  Nice to find the smoking gun. Good luck with the project.

So you were talking about the condition of the rest of the pistons... Maybe it's just the camera or deposits on top of them, but I don't like the looks of them at all. Other than the dent, number 1 looks OK, but the rest of them worry me. Pitting on top? Detonation maybe?

Is it a trick of the camera? Are all the rest of them smooth metal underneath the crud?

Edited by Captain Obvious
typo
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I bought a 78 parts car cheap mainly for the 5 speed.  I ended up using the engine in my 76, it was in much better shape.  Just planting a seed.  Your engine looks like somebody has spent too much time in there.  I don't think that Nissan numbered the pistons so the mismatch you saw might not be important.  I see some pretty deep scores in the cylinder you showed, so you might need new pistons anyway.  But then you're looking at pistons, a bore job, rings, all the extras...spendy.

Any L6 engine up to 1984 will drop right in.  A 280ZX parts car with a 5 speed would be a nice find.

 

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Oh, and about the number stamped on the top of the pistons... The stock pistons should have a number on them, and there should be faint stampings on the block deck surface for each cylinder and the numbers should match. At least the first number. The stock stamping numbers represent "size", not "location".

That "3" stamped in your piston does not look like a stock stamping to me though.  Here's a couple pics from my engine:
P1150438.JPG

P1150466.JPG

 

 

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12 hours ago, Captain Obvious said:

Well there's your problem!!  LOL  Nice to find the smoking gun. Good luck with the project.

So you were talking about the condition of the rest of the pistons... Maybe it's just the camera or deposits on top of them, but I don't like the looks of them at all. Other than the dent, number 1 looks OK, but the rest of them worry me. Pitting on top? Detonation maybe?

Is it a trick of the camera? Are all the rest of them smooth metal underneath the crud?

I'll be sure to give everything a good wipedown and check. Now that you pointed it out, I can totally see the difference between 1 and the rest.

11 hours ago, Zed Head said:

I bought a 78 parts car cheap mainly for the 5 speed.  I ended up using the engine in my 76, it was in much better shape.  Just planting a seed.  Your engine looks like somebody has spent too much time in there.  I don't think that Nissan numbered the pistons so the mismatch you saw might not be important.  I see some pretty deep scores in the cylinder you showed, so you might need new pistons anyway.  But then you're looking at pistons, a bore job, rings, all the extras...spendy.

Any L6 engine up to 1984 will drop right in.  A 280ZX parts car with a 5 speed would be a nice find.

 

Thats a good idea. There is a local 280z and tranny combo for $450. But its been sitting out of the car for a year or two. I'll probably pull the pistons first before jumping on another engine. I dont want to risk having two bum engines. 

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Did a quick clean of the piston tops. @Captain Obvious thoughts? Im no expert on internals yet, but #6 definitely looks like something was flying around in there. The rest look okay for what they are. Looks like #5 and #6 also had a run in with a valve!

(Hopefully they upload in order starting with #6)

Cyl #6 Clean.jpgCyl #5 Clean.jpgCyl #4 Clean.jpgCyl #3 Clean.jpgCyl #2 Clean.jpgCyl #1 Clean.jpg

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I take it back. Other than the valve dents and occasional other minor blemishes, those pistons don't look bad at all. If you don't have a really good condition other option, I'd run those. Must have been a trick of the camera. I was really expecting serious destruction.

And you can see the sizing numbers now. Not cylinder number. It was just luck that the only one you could see before was #3.     LOL

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One of your pictures, and the damage you've found, made me wonder about the camshaft.  Might be a performance, high lift cam.  A picture will tell, look for new stamps on the ends.  The lobes will have a smaller base circle if it's a regrind.

Detonation causes damage that looks like foreign object damage.  Might be that somebody built a "race" engine.  Check your head also  to see if it's been shaved.

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13 hours ago, Captain Obvious said:

I take it back. Other than the valve dents and occasional other minor blemishes, those pistons don't look bad at all. If you don't have a really good condition other option, I'd run those. Must have been a trick of the camera. I was really expecting serious destruction.

And you can see the sizing numbers now. Not cylinder number. It was just luck that the only one you could see before was #3.     LOL

Same! I think I will run them with some fresh rings and a deglaze. Overall compression was averaging around 90psi so I think its safe to do rings while im here.

13 hours ago, Zed Head said:

One of your pictures, and the damage you've found, made me wonder about the camshaft.  Might be a performance, high lift cam.  A picture will tell, look for new stamps on the ends.  The lobes will have a smaller base circle if it's a regrind.

Detonation causes damage that looks like foreign object damage.  Might be that somebody built a "race" engine.  Check your head also  to see if it's been shaved.

You got my hopes up 😄 I dont think it is base on the pictures. I did front, lobes, and rear.

 Cam Front.jpgCam Rear.jpgCam Lobes.jpg

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10 hours ago, Barefootdan said:

Same! I think I will run them with some fresh rings and a deglaze. Overall compression was averaging around 90psi so I think its safe to do rings while im here.

Well you've got two obviously bent valves, and marks on other pistons as well. That makes the whole top end suspect to me. The point is, the compression numbers may be more related to issues in the top end than the rings. However... You're this far in and it would suck to do a bunch of work on the top end and put it back together with a tired lower end.

Who would ever do such a thing.              :ph34r:

 

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2 hours ago, Captain Obvious said:

However... You're this far in and it would suck to do a bunch of work on the top end and put it back together with a tired lower end.

Who would ever do such a thing.              :ph34r:

 

Exactly! I would be so bummed putting a fresh head on only to find out that the rings were also bad....Well since we're this far I may as well pull the block! It could use a deep clean anyway 🙂 

Started tearing the head apart more today. Got the rockers and cam out. I'll need to get a spring compression tool to move forward. 

Planning to send off the cam for a stage 1 grind as well as the rockers to refinish. Darn EFI limits me on the cams!

Also was able to start cutting some rust out of the floor pans. I think I'll get the big chunks out, weld in new plates, then POR15 the entire floor pan to tackle the deeper surface rust. 

I may also work on cleaning the intake manifold:

  • Charcoal canister
  • EGR
  • BCDD
  • Cold Star Valve

I think we should still retain decent idle even with the above gone. Phoenix never gets cold. Main goal here is just to make everything look better.

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About the spring compression tool... You won't be able to use the "hooks on the cam" version if the cam is removed. (Duh.)

Here's some pics of my latest valve spring took contraption. A little faster to use than my previous contraption since there's less wrench turning:
P1180619.JPG

P1180622.JPG

P1180626.JPG

 

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9 hours ago, Barefootdan said:
  • Charcoal canister
  • EGR
  • BCDD
  • Cold Star Valve

I think we should still retain decent idle even with the above gone. Phoenix never gets cold. Main goal here is just to make everything look better.

Well lets see... If adjusted properly and working as designed, absolutely none of those items should have any effect at all at idle.

Charcoal can - Disabled at idle
EGR - Disabled at idle
BCDD - Disabled at idle
Cold star valve - Only active while cranking the engine, so disabled at idle

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2 hours ago, Captain Obvious said:

Well lets see... If adjusted properly and working as designed, absolutely none of those items should have any effect at all at idle.

Charcoal can - Disabled at idle
EGR - Disabled at idle
BCDD - Disabled at idle
Cold star valve - Only active while cranking the engine, so disabled at idle

Oops, i guess a better term is just overall running of the engine. Trying to remove as much unneeded stuff as possible while still retaining whats *needed* for a smooth experience. 

I read that you can also take out the TPS and AAR but it start to have negative impacts. Is that right?

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How much are you planning to spend?  Your engine seems to have seen a lot more abuse than most.  You might want to do a thorough inspection before buying parts.  That $450 combo might be a deal once you add up the cost of parts to fix what you have.  Cam + rocker arms + pistons + bore + >>>  

image.png

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I removed the egr and thermal switch plus the warming plate on my '77.

I think the bcdd and tps, cold start valve would be best left on the motor. They serve a good purpose in my reading and I've read so much now I forget. Too much too soon before my rebuild of the efi motor.

 

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26 minutes ago, Zed Head said:

How much are you planning to spend?  Your engine seems to have seen a lot more abuse than most.  You might want to do a thorough inspection before buying parts.  That $450 combo might be a deal once you add up the cost of parts to fix what you have.  Cam + rocker arms + pistons + bore + >>>  

image.png

Eh, not a ton. But I dont mind spending more to know it is done right. Rather than picking up the $450 combo, see it also needs a rebuild 😅 As you can tell, I am not a betting man.
Id be happy if I could freshen up mine for under $800. Rings, deglaze (bore/hone if needed), regrind the cam and refinish rockers, new seals throughout, misc block off plates, new timing kit and waterpump, new head bolts.

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31 minutes ago, siteunseen said:

I removed the egr and thermal switch plus the warming plate on my '77.

I think the bcdd and tps, cold start valve would be best left on the motor. They serve a good purpose in my reading and I've read so much now I forget. Too much too soon before my rebuild of the efi motor.

 

Ill check out the thermal switch and warming plate removal. thank you! I agree, tps is better left on. Is BCDD pretty mandatory? To be honest, that is a bit of a wizard device to me (like carbs!). 

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7 minutes ago, Barefootdan said:

Eh, not a ton. But I dont mind spending more to know it is done right.

That was my point.  I'm just saying do the math first.  That motor looks beat upon.  Good luck.

Take a picture of the side of the head where "N42" is cast in.  You can tell if the head has already been shaved/skimmed by the distance from the bottom.  While you're there you might as well check flatness.  If it's been overheated (likely) it might be warped.

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It looks like there is about a 1/16th of an inch. Head is definitely not flat. I was able to slide a .3mm feeler, granted my straight edge is not super precise, but it (straight edge) felt flat on the block. On the head, it rocked on the 4/5 cylinder wall regularly. I different angles and positions of the straight edge to try to rule that out. Is this too much to shave?

 

Head Casting.jpgHead Casting 2.jpg

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you should make sure you have a VERY clean head surface, then use a good quality straight edge, go from one end of the head to the other with feeler gage. you should go diagonal as well.

IF you need to get head work I would suggest you ask around, you want some one that has worked on L type heads. there is a lot to take into consideration. I looked into it some, there is not only surfacing the mating surface, but also you have to make sure the cam tower surface is not bowed. If so you end up having cam issues. I have read the correct thing to do is surface both sides and then shim the cam towers to keep the geometry correct and the chain length correct. You may want to contact someone like Datsun Sprit in VA, they seem to have a pretty good rep.

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