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!

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

Ya I drove it an hour home from the shop at 60mph on the freeway. Also just got back from picking up my son at school with it and had 4 people literally yell out of their car in traffic to tell me how sweet the car is. Runs perfect. Sounds great. No smoke. I don't hear any unusual sounds. Idles very smooth.

Edited May 6, 20168 yr by zmanoside
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And I was wrong. The mechanic said he absolutely checked the bore size, it is standard he said. He also said that thing would sound like $^!# if It wasn't!

You got your car back way quicker that I thought. That almost never happens with a job like that. Good shop.

Well that eliminates piston "rocking" so...........??

38 minutes ago, Lumens said:

You got your car back way quicker that I thought. That almost never happens with a job like that. Good shop.

It would have been only a 3 day turn around if the shop owner knew how to use the Internet! The Pistons he originally ordered were dished Pistons. I had to get online for him and order them and have them shipped which took an additional 4 days. It was miserable for me though. I had sinus surgery and it got infected post op which sucked. I had to pick up the car with the worst headache I've ever had in my life!!!

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.

^^^agreed^^^. A few unanswered questions for sure. 

I'd be curious of how the bores looked. Standard bore in 2 rebuilds? 

Honed several times makes for s sloppy fit . Sloppy fit no good. 

I would ask for numbers since the mechanic was so emphatic that he checked.

what is the piston , bore clearance now?

glad you are back rolling 

35 minutes ago, Zed Head said:

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.

I texted the previous owner all of the pics of the Pistons along with me telling him that I spoke with hosomi on the phone and that there wasn't ITM Pistons in there. No response...

3 hours ago, zmanoside said:

I texted the previous owner all of the pics of the Pistons along with me telling him that I spoke with hosomi on the phone and that there wasn't ITM Pistons in there. No response...

Not surprising...