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sscanf

1976 EFI Overhaul

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My apologies if this is a duplicate, the system seems to have just swallowed my carefully crafted posting (telling me I wasn't logged in). Here goes again.

I just bought a 1976 280Z as a project car. The body is in good shape but its been partially dismantled. The previous owner took it apart to move some performance parts to his new Z. So it came with the EFI intake/throttle off the car (along with a bag of misc stuff). Exhaust is missing (I have MOTORSPORT TBC Coated 6-1 Header, and MSA premium exhause on order from the Z store). Bumpers are off. Interior taken apart. Drum brakes need work (in-progress - Front disks/calipers look great though). Previous owner upgraded distributor to ZX/electronic, replaced fusible links with fuse block, new dash cap/carpet.

My first goal is to get it put back together and running to see what I have. Since the EFI intake/throttle is off the car I decided to replace the injectors (on order) and clamps (one side of the fuel rail had standard hose clamps rather than EFI clamps - looks like one of the injectors was replaced a while back). I have mostly stripped the manifold and would like to give it a good cleaning (along with the throttle which I have removed). What is the best way to clean them inside and out? Carb cleaner and elbow grease? Have it dipped? Something else?

Putting it all back together will be an adventure. The previous owner did mark the wiring harness (I will clean all the contacts with deoxit) and I found the Datsun EFI Theory/Troubleshooting book on-line - I think most of my questions will be answered there. I will replace all of the vac hoses and any water/fuel host that doesn't look new (some look newly replaced). I have a new throttle gasket on hand. I will get all new injector hold-down bolts (not screws!) and tighten them appropriately when I reassemble.

Any other suggestions while EFI intake is off the car? What would you do?

Thanks,

Dan

PS, Here it is:

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Replace all fuel hoses (including those at pump and tank.

Your new exhaust will drone ~ 2800rpm....http://atlanticz.ca/zclub/techtips/exhaust/index.html.... get a glass pack too.

For EFI, this should keep you out of trouble: http://atlanticz.ca/zclub/techtips/EFI&fuel.htm

For the throttle body, spray it with throttle body cleaner.

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I used lacquer thinner from a paint store, about $10 a gallon, and a heavy duty de-greaser from a bar-b-q restaurant I do maintenance for which was free. Scotch brite scouring pads (also from the restaurant) a round wire brush for a drill and alot of that elbow grease you speak of. Cleaned internal parts as well as intake, valve cover and suspension parts. Oh yeah get some of those toothbrush looking wire brushes out of the welding section at Lowes. Lacquer thinner for the really greasy then finished up with the degreaser and hot water. I'm happy with the results and carb cleaner is pretty much lacquer thinner but more expensive. My .01 cents worth of advice.

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Saw this method the other day -

Looks promising. Don't try it in the garage.

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For cleaning the connectors, plain white vinegar works well too if you don't have deoxit close by. Also, buy some of the replacement connector off ebay and change them out. Your old ones I'm sure are brittle. Don't cut and splice though, just remove the two pins from the old connector. (clean them with your contact cleaner of choice) and then stuff them into the new connectors. It makes a fast nice looking install. Much better than soldered lumpy heat shrink look. :)

BTW. You will have to use a really small screwdriver to release the tabs that hold the pins in the connector. If I get time this weekend, I'll take some pics and post.

Lenny

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Thanks for all the references and advice. The links were really helpful, especially when it came to putting things back together. I also have the Fram G3 fuel filter ready to install (and a new factory fuel filter) before I try to start this thing. I cleaned mainfold without the torch (but was tempted). I used two cans of throttle body cleaner and lots of brushes. I'm pretty happy with the results. Here are some detailed photos (including the before picture) that might help someone else out in the future. Note, I replaced the screws with bolts but only hand tightened them with a screw driver (nut driver for future removal). I had to cut a slot with a dremel to get one of the screws out (and most of the others did not come out easy).

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Before

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Parts

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Detail

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After

I spent some time prepping the head for installation tonight. I have the new header/exhaust on-hand along with new studs and bolts.

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Edited by sscanf

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[ATTACH=CONFIG]52373[/ATTACH]

Assuming the original Phillips screws aren't all smeared out, I recommend that you switch back to the original factory hose clamps. Why? Because OEM Nissan is stainless, while the aftermarkets are zinc plated steel.

Take a magnet to the OEM's and then to your new ones. I bet the new ones are magnetic, while the originals are not.

I've been known to grab a couple of the OEM Nissan clamps from the junkyard while I'm there. I use 'em all over the place. They're not just for Nissan anymore.

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Yep, the new ones are magnetic but... half of the original clamps had been replaced with water hose clamps during a previous repair. Will keep this in mind in future.

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Sorry I didn't get to you sooner. On the good side, if you do decide to replace them all with OEM, you can replace the clamps without taking the hoses off the nipples. If you are careful and are comfortable working with small easy to drop parts, you can take the screws completely out and spread the clamps enough to get them onto the hoses without taking the hoses off.

I really don't like the water style (with the slots in them) for fuel line applications. The shots cut into the hoses...

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I agree with Captain. I wouldn't use non-stainless and/or slotted clamps. Those hoses can come apart (not just come off) if poorly clamped. If you have a fuel leak, fuel will run over the hot exhaust manifold, and your car can go up in flames. I once had a fuel filter leak on my '66 Mustang, and yup, the engine caught fire. Fortunately the damage wasn't a fraction of what it could have been (especially considering the car was in my garage when this happened).

Anyway, don't mess around with the wrong clamp. Get some of these:

http://www.summitracing.com/parts/CCA-G3912/

... in the correct sizes, of course. (I don't know whether this one is the right size.) They are extremely flexible and do not cut into the hose. These are the best clamps I've ever used.

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Got my six today and they look great! Probably still would be stressing had you not shared your information, thanks again sscanf. Thank you for telling about the O rings already in the box, I was about to waste $18 for those.

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The clamps I did use were the ones that came with the new injectors. I will get some of those nice Gator clamps next time I put an order together but will use these meanwhile (assuming the injector manufacturer would supply clamps that will be sufficient for at least short term service). I'll roll it outside, watch closely, and be ready with a fire extinguisher the first time I give it a try.

Next question is on cleaning the old gasket material off the head. I spent an hour on it last night with some solvent (simple green) and a green scotch brite pad. It looks (and feels) good to me but I don't do this every day. Just how perfect do I need to get it? I started with a steel razor blade but got nervous about gouging the aluminum. I used a plastic scarper for a while then moved to the scotch brite. Is there a better way to clean it? How do I know when I'm done?

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Glad it was of help to someone. A couple of things I did not mention... I coated each of the o-rings with a tiny bit of motor oil, just like I do an oil filter before installation. I installed the injectors onto the rail before I screwed them into the manifold. This worked well except that the thick plastic spacer (which is not shown in the datsun diagram BTW) wants to fall off when you flip the whole thing over to install onto the manifold. I got past this by using a piece of tape to hold them until I they were seated, like so:

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Next question: I have new studs in hand (the studs that hold the exhaust manifold). The old studs are out of the head . How much should I tighten the new studs? Just bottom them out or tighter?

Edited by sscanf

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In general, I believe that studs are meant to be finger tight. It's the nut pulling up on the stud that provides the clamping force. Some people do tighten them in using doubled up nuts, which tends to keep them in the head next time you remove the manifold, but it will also pull the first thread or two up out of the head and add some deformation from the shaft of the stud. You're probably seeing some of that while you're removing gasket material.

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Yes, I did see some of that. The various scraping tools kept catching on tiny ridges around the stud mounting holes. In reading up on installing these studs I have seen both never-seize and lock-tight prescribed. Which is it? both?

I was goig through the exhaust parts last night and noticed that the z store sent me the wrong gasket with the header :( - I have a phone call to make. Probably not going to get this done over the weekend like I had hoped.

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A little more info on installing new studs - I found the following info at Auto Service Professional

In the majority of cases, screw the studs into the block FINGER-TIGHT ONLY, or with a very slight amount of pre-load (specific manufacturers may recommend as much as about 8 to 10 ft.-lbs. of pre-load). Do not double-nut the stud and tighten severely. Remember — the torque value given for the installation refers to the tightening of the nut only, not the stud itself!

If you desire a “fixed” installation (locking the studs in place for future servicing ease), the studs may be chemically adhered to the block threads. If stud removal is required in the future, the application of heat will break the compound down. If a locking compound is used, be sure to immediately install the main cap before the compound sets, to avoid any possible misalignment of the studs in relation to the cap. This means installing the cap and tightening the nuts to specs, before the thread compound hardens. This allows the necessary preload to be placed on the stud-to-block thread engagement before the compound hardens.

Remember: The use of a locking chemical really isn’t necessary, unless you want to ensure stud position during repeated and hurried main cap changes.

When installing the studs, simply make sure that full thread engagement has been achieved. In other words, make sure the studs "bottom-out," with all threads engaged.

I will be installing them dry (but with anti-cease on the nut threads).

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I just called the Z store and they had no problem sending me out a new gasket. I asked why an OEM gasket was no good and they told me it was because it had metal facing on the manifold side that causes a heat problem with the header.

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Quick update - I have the header and the EFI on. Now trying to figure out how to hook up everything. I am getting most figured out and the previous owner did mark many of the leads. Its taking some patience though...

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If you get stuck, PM me and I'll give you my number. I can talk you through any of the hookup/debug of the EFI. I have been buried in the wiring diagrams and detailed operation of the L-Jet over the last two months while designing a replacement ECM/ECU.

-Lenny

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Its been a while.... So here is what happened:

April gets busy around my house. The grass starts growing, I have to mow it. The house needs painting, I have to paint it. The wood needs stacking, I have to stack it. etc.

The mower is now put away. The house is painted. The wood is stacked. The Z awaits.

So, here is what happened: I did get the EFI wiring hooked up in April and tried to start it. I used a combination of labels provided by previous owner, manuals, and wire memory to figure it out. Once this was done, the engine cranked just fine but there was no ignition at all, it didn't even try. A short investigation revealed that the fuel pump wasn't running. I put a meter on it. No (well, very low) voltage. That's when I was over-run with all the homeowner stuff.

Finally, two weeks ago, I drag out the EFI manual and turn to the most basic wiring diagram. Within 5 seconds I knew what my first problem was. The previous owner had removed the AC and there were a few dangling wires. Basically any wire I saw without a mate I assumed was part of the AC. This was not quite true. The EFI ground wire (red!) had been removed by the previous owner (and he did mention it but i recalled it as he had disconnected the fuel pump - and there was a dangling wire at the fuel pump that I reconnected). So, I sort through the "leftovers box" and, sure enough, I find the snipped off EFI ground wire. I take my time and nicely splice it back in. Roll the car out on the driveway, turn the ignition on (but don't crank it) and I hear the fuel pump! I leave it and inspect the fuel lines - its all good. I crank it for about 30 seconds and it fires!

It ran pretty rough for a few minutes but not awful after that.

It did not like to start at all, always took 30 seconds or so. I decided to replace the cold start valve (the only injector that had not been replaced). Now it fires instantly every time. Still runs rough when cold. Pulls strong after warm up.

What I have done so far

All (7) new injectors (with new hold down bolts, not screws!) and thorough throttle body cleaning.

New vacuum hoses.

New motorsport header and exhaust (not sure I like it - sounds like a truck to me)

All new brakes (drums, shoes, cylinders in back, calipers, pads in front - rotors were in good shape. Old calipers leaked. New master cylinder)

Wires, plugs, cap were new via previous owner.

Fuel pump new via previous owner.

New lug nuts (it was an adventure getting the old locking lug nuts off without a key - broke lots of craftsman sockets).

New fuel filter

Lots of other misc small stuff.

Plan on checking valve clearance and timing next. Then back to the trouble shooting section of the EFI manual.

Quick update - I have the header and the EFI on. Now trying to figure out how to hook up everything. I am getting most figured out and the previous owner did mark many of the leads. Its taking some patience though...

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This thread is kind of old but its a good place to pick things up again. Since I last posted, I had to work through some other problems covered in other threads (vacuum leak through bcdd, bad ignition module, bad AFM). All taken care of now.

Summary: 1976 280Z bought about two years ago, had to trailer it home with the fuel injection in the back hatch. No exhaust (not even a manifold). Body in great shape though.

Here's a summary of what has been done... I'm sure I'm missing something.

  • New (rebuilt) AFM
  • New (rebuilt) ZX distributor/ignition module
  • BCDD vacuum leak repair
  • Bad Dog frame rail kit
  • New (well, used) Slot Mags and Tires
  • 240Z front bumper (still needs some work)
  • New Coil
  • All (7) new injectors (Standard brand FJ707T) and throttle body cleaning.
  • New vacuum hoses.
  • New MSA coated header and exhaust
  • All new brakes (drums, shoes, cylinders in back, calipers, pads in front. New master cylinder)
  • New Clutch, slave cylinder, boot
  • Wires, plugs, cap were new via previous owner.
  • Fuel pump new via previous owner.
  • New fuel filter. Oil Change. Plugs. Etc.
  • Lots of other misc small stuff.

I did everything myself except install the frame rail kit. The guy that did the welding for me went over it from end to end and said it was in great shape.

Anyway, the news is: My Z is on the road! Runs great! It goes like mad. I have not taken it over 5000RPM yet but it gets to 5000 in the blink of an eye. All of the old problems seem to be gone (no cut outs, tachometer is perfect - not jumpy any more). I still have some roughness when its cold but after a minute or two its smooth.

A while back I replaced the aux air intake with a ball valve which I open about half way when I first start it then shut it off after a minute or two depending on the outside temp. I may try the original aux air again now that other issues have been solved.

BCDD is still disconnected. Temp gauge is not working (neither is the clock). I still have to put the interior back together - I had stripped it before brining it in for welding. Should get that all done this weekend. I'm going to flush the cooling system this weekend in hopes of getting the heat working. Need to work on the bumpers. Get a nice old aftermarket stereo in it. Etc...

Thanks again to everyone on this list who has helped me along the way.

Dan

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Edited by sscanf

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