Well I just bought this car. It's a 1970 240z with a P79 head and a F54 block out of a 81-83 280zx non turbo. The complete engine was rebuilt less than 6000 miles ago by a very reputable Datsun engine builder, Eiji Hosomi, out of Datsun Spirit. When I bought it the PCV was capped with a freeze plug and there was a breather hose coming off the valve cover. This was smokey and stinky since I've had it. The previous owner said that it had always smoked a little but recently had smoked more. Doing a lot of reading I figured I would uncork the PCV hoping to reduce the blow by coming out of the crankcase and setup a catch can with a breather filter on top. I did just that this morning and this thing is smoking even more now it seems. There is white gray stinky gas smelling smoke almost billowing out of the catch can breather filter. I drove it around the block and she runs SOLID. She just smokes a lot out of the catch can to where it's coming into the cab and it's unbearable. I've read and read. Rings are shot? Compression test? Leak Down? The car runs just fine I would think the compression is fine....I'm bumming. I have money left over from buying the car to cover fixing stuff, that I was hoping to break at the track, not to get it ready for the track! Any insight is appreciated. I need to hit the sac. Night shift sucks. I've been up since 3pm yesterday and I am beat!

The casting looks like ITM's. Here is a couple pics of an ITM flat top before it went in one of my F54 blocks. Amazing.....I've never seen anything like those broken skirts. Good luck in finding the cause.

.......on second examination, mine don't have the markings you are showing in your pics.

I probably did mean ITM. I knew it was IT something...I looked at Datsun spirit website and saw a picture of there flat top Pistons they have for sale. The is a mark on top of the piston that say STD. This same mark is on each of the Pistons I have in the box.

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

Found it.  Taiwan Piston.  https://www.google.com/#q=tik+pistons

http://www.tik.com.tw/

You have a mystery here.

 

Edited May 4, 20168 yr by Zed Head

Really nice work Zed Head.......you should be a detective! Those aren't ITM pistons and therefore is a mystery block from a mystery builder. I wonder what brand of pistons California Datsun uses?

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

Were the skirts all broken on the same side? A measurement from the top to the pin center and from the pin center to the bottom of the skirt would be interesting to compare with stock pistons.

Are there marks or damage of some sort on the crankshaft? Hopefully the mechanic in S.D. is checking dimensions between the sets. Can't wait to hear what he says about it.

Zed Head, I couldn't make out what it said (the markings) on those pistons until you posted it. I can see it now that I know what I'm looking at.

 

Is ITM it's own manufacturer or are they made by someone else?

Wow, give that man a cigar! Well I'm going to call Mr. Hosomi tomorrow and get more details from him. I will text him the pictures of the Pistons and see what he says. The car is back together and in my garage. The Pistons that were installed into my car today were ITM Pistons. I'll clean up the broken Pistons and take more detailed pictures of them and the pieces of skirts that I have in the morning. I'm going to take my son for a leisurely drive down the coast with her in the morning. He's 4 and is IN LOVE with dads "race car". He is just as excited to have the car back in the garage as I am and I need to get another 450 break in miles on her... I'll post up pics in the AM.