Zed Head

So you've driven it? Loose pistons are kind of noisy.

He has the "monkey motion" shifter. Seems like the assumption is that the tail of the transmission is moving up and down. Would be good to confirm that that's the case. On old 240Z's I'd guess that the crossmember mounting points get rusted out sometimes. You might have good parts bolted to a flexy body. Might check the motor mounts also. The trans mount is only meant to handle so much.

I hope the mechanic checked bore size and didn't just assume that STD was correct. There are some breaks in the assumed sequence of events, like the assumption that this is a Datsun Spirit engine. STD of the ITK pistons could be STD for a different engine. Or they are STD for an L28 but the bore isn't STD. Apparently loose pistons can slap and break. There's a bunch of Jeep forum comments on skirt breakage. Whatever the cause, the dimensions should be checked before reassembly. I don't see any numbers in previous posts.

Those wrist pins don't look in very good shape either. Not 5000 miles of wear. Overall, it looks like a set of used high-mile pistons. Maybe the skirts and ring lands got damaged/cracked when the pistons were removed from the old engine.

I should say though, that even with heat and PB Blaster, I still broke one. That's why the nut-buster/cracker sounds like a good idea. Same reason I go directly to Vise-Grips on the brake fittings. Shifting the odds.

I used MAPP but if I had oxy-acetylene I would have used it. It's a lot faster and more concentrated.

Do you have clear title?

You might find also that it only moves when it's hot. I've had that happen on several parts. Heat it, turn it, heat it, turn it. I've also had the stud come out with the nut attached. I actually re-used it as a bolt, it was the only one I had at the time.

They don't look terrible. The thing about rust is that it expands when it forms. It's not really two parts rusted together it's rust filling the gap between two parts. At least you only have one part rusting. Those brass nuts will probably expand quite a bit with a torch on them, and they have good solid flats to fit a wrench on. I used stacked extensions and a breaker bar from underneath on mine, with a good socket, not a cheap loose weak socket. You get one good shot, prepare well. It's a dice roll, still.

Well, thanks for providing the puzzle. Beat's the heck out of a crossword. You might have your builder compare dimensions of the new pistons to those. People often pick a piston to swap in based on pin diameter and height and just make it work. Honda 500 pistons for example, seem to be popular. Maybe they missed skirt length, or overall piston height, and it banged off of the crankshaft. Do you have the skirt pieces? Look for impact marks. That Taiwan site does have some Nissan pistons if you use the drop-down menus on the left, on the Products page. More of a curiosity at this point, but might offer a clue. http://www.tikparts.com/index.php?option=product&lang=en

Found it. Taiwan Piston. https://www.google.com/#q=tik+pistons http://www.tik.com.tw/ You have a mystery here.

STD is stamped on the top of almost all standard size pistons, of any brand. The shape of the letters and stamp depth might be a clue though. I found a picture of what are purported to be ITM pistons, on the CaliforniaDatsun site. Salt grain. They don't show that odd trademark. It looks like a T and a K to me, with maybe an odd-shaped "i" in between. But here's the ITM pictures. from here - https://www.californiadatsun.com/cylinder-head-parts/flat-engine-piston-set.html

But are they? Should be marked. If they're not then it's not the engine Hosomi put together. Is this the ITB mark? Don't know much myself. Edit - did you mean ITM?

More questions... What's the brand of the pistons? Is it possible that the skirts were too long and actually touched the crankshaft? Still not seeing how bits of ring got past the oil scraper and the piston structure. Yes, there's an indentation but it closes up at the bottom. No obvious path for the top ring fragments. Kind of looks like somebody opened it up, maybe when they changed the head, and really hacked a bunch of stuff up. Maybe cracked the piston skirts when they were in there. Or had the pistons and rods out and cracked the skirts then, playing with them like rattles.

I missed that. It does kind of hit you in the face though when you see it. In GDT terms it's kind of an odd spec. With both parts on the low end. the piece is .030 mm smaller, but on the high end it's .070 mm smaller. It's also possible for the piece to be bigger than the hub dimension. But it looks like Nissan wanted it smaller. Besides that, how big is .030 mm? 30 microns isn't much. Didn't realize my post overlapped zKars. I don't really know where that noise-reducer sits. Just remember reading about it.

Forgot to say, if you mean the bronze noise reducing washer, Nissan got rid of that later. It's described in the Technical Bulletins section of the How To Restore book. All you really need to do is match the dimensions. Ideally, they should be verified anyway. Who knows who's been in there?

The Rear Axle chapter gives the dimensions that need to be matched for the hub and the spacer. John Coffey has suggested that a piece of metal pipe could be machined and used in place of the factory spacer. If that's where the shimming needs to happen. The "Distance Piece".

The Crane 6300 instructions above imply that the OE ignition module, in the OP's case the ignitor or power transistor, is used to trigger the Crane system. Basically, the system needs to be set up with the stock power transistor, then the Crane box is inserted in between. Might be possible to replace the PT, but that's not what Crane is saying.

And, to be clear, when Crane says magnetic trigger they mean a variable reluctor trigger. Which is a sine wave of varying voltage, from very low (below 5 volts) to very high (well above 12), not a square wave. Many people do run the GM HEI module on the square wave from the 280ZX turbo ECCS system, even though it's also designed for GM's HEI magnetic trigger. Maybe somebody has discovered that the Crane will do the same? I think we'd both agree that it's not intended for this application. Not even sure how it got in there unless somebody put together one of those name lists. This isn't the best learning project for the OP. But there's a lot of interesting stuff there. Summit always has the best information - http://static.summitracing.com/global/images/instructions/crn-6000-6300.pdf Edit - wrong part number. Fixed.

This thread isn't really about the Crane system at all. The OP might be better served to go back to an ignitor until he gets the basics sorted. Here's a document showing similar to what he's dealing with. Already pretty complicated. http://www.jimwolftechnology.com/wolfpdf/280Z31-INJ-MAF-88ECU-UPGRADE-6pg-Revised-12-11-13.pdf

Not sure what you mean by "CPS". You really need to browse through the Z31 EFEC chapter to see how the ignition power transistor is triggered. Your Crane box is taking the place of the power transistor. It doesn't get power all the time when the key is On (if that's what you meant by CPS). No offense, but you are way behind where you should be to safely get that engine running. And I mean safe for the engine. You thought you had a magnetic trigger in the distributor because you have a magnetic trigger Crane box, and now you're checking for power at the Crane box with the key on. You have enough information to figure it out but I don't think it's going to happen on an XBOX. As I said, no offense intended. Your stumbling and fumbling at this point though. A good computer and internet connection is an important tool. Edit - you probably meant CAS instead of CPS. Diagnosing the CAS is a problem that everybody has. The best description I've seen is on Hybridz. Scroll down to "Dizzy Wire Colors!" - http://forums.hybridz.org/topic/23244-megasquirtnspark-mssmsns-installation-guide/

He'd be using the 5 volt square wave from the Z31 ECU, if anything. He has a lot more to think about than just the Crane box. Better understand all of it before taking it out on the road. And he said he has an " in cockpit crane retard control". Which would be the Crane HI-6 TRC CD. Lots of stuff to figure out.

Who knows what else has been done to it - http://portland.craigslist.org/mlt/pts/5562702804.html

I've done similar things in the past. One of the great things about these old cars is that they are primitive enough that you can understand things at a fundamental level, to fix problems. Ponder how duct tape on the outside is going to withstand the pressure from the inside. It's not really doing anything. The "SS" brake lines are really just brake hoses with a braided metal protective sheath in place of rubber (which is probably fiber reinforced). More durable, but most likely have little effect on performance. I have a set up front myself, but don't know if I'd buy another. When your brakes were slowly dying, the first thing you should have done, probably, is to bleed them. And, as I understand things, when the reaction disc is missing the symptom is an on-off brake action. Probably why they call it a reaction disc. It moderates the reaction. The disc in in the booster, not the MC.

The chest pounder says that some flow back to the pump when the thermostat is closed is necessary to prevent cavitation. Since you've closed off the manifold/carb route maybe another line is needed. I wonder if How to Modify book has some suggestions. Edit - nothing there. They run open flow restrictors. I don't even know why that "jiggle valve" piece is there. http://www.hemmings.com/magazine/hcc/2005/02/Some-Like-It-Hot/1281095.html