Zed Head

I remember some discussions about the topic from the past. I'll dig around. I wonder if anyone has a set of ITM pistons they could examine.

This got overlooked as a possibility for the ITM confusion. Could be that ITM outsources to TIK and TIK quality isn't very good. How many people have bought Timken for their reputation then opened the box to find National brand?

Yep, you're on the new owner of old car path. Expect more. Study up on ignition modules.

I was kidding, of course. I feel a little bad that the spot-light is now on Datsun Spirit, who has a generally excellent reputation. I did mean my comment though about change there being possible. Shops get big and busy, they hire new people and give them responsibility, and things happen. Could be an honest mistake. You've done more than enough and it was a good cautionary note for everyone. With grannyknot's recent selling issue and this, and past CaliforniaDatsun problems, it shows that you have to look out. I might send a message to the guy in that other thread (Richie, apparently), with a link to this one, just to give them a chance to address the issue. Maybe Diseazd or Carl Beck has a view. Still think that there are written records out there somewhere. You wouldn't have them though, the other guys would.

Thanks for the entertainment anyway. I wonder if things aren't slipping a little at Datsun Spirit. A fairly short while ago it looked like somebody else was taking over operations. Maybe they're cutting costs and milking the reputation. The guy never replied to my question.

And, the head has been replaced. Could be the whole engine was swapped at the shop that did that work. Might not be the engine Kelvin bought. He might have been ripped off and didn't even know it.

Working from memory is not the best way to solve these kinds of problems. Datsun Spirit or Kelvin must have some sort of written record. Just because typed the words in to an eBay ad doesn't mean they happened. Does nobody have a simple part number from a receipt or estimate or build sheet? Was the engine shipped or installed in the car? Did more than one engine ever sit in the same place? Does Datsun Spirit do simple repair work besides builds? Less emotion, more fact-finding is the way to go. These are all unfounded accusations until somebody shows some proper documentation.

Still wondering how the ring fragments got past the skirt tops. There's no path. Pistons aren't ITM. Where'd they come from? Does Datsun Spirit keep records of the block serial numbers? Each one is unique. Might offer a clue. In the long run, doesn't matter much to zmano. It does leave open questions about the other two parties though. Hate to say.

Maybe monkey motion refers to what happens to the shifter in second gear. Never did understand why they called it that.

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?