Dished pistons for NA?

[Zed Head]

These guys might be able to help.  Looks like they have either side of what you need.  You might try looking for 0.5 mm over, instead of .020" over also.   Who knows if the people you are talking to are dong the conversion for you.  Confirm your bore size also, just to be sure that the machine shop got it right.  You never know.  Might find the right pistons but then find the bore size is off.

http://datsunspirit.com/shop/86mm-bore-flat-top-pistons/

 

 

[siteunseen]

Rebelloracing.com would have them most likely, if you're in a hurry. I have seen tens of adds on ebay at a time for a small oversize ITM piston to fit a slightly cut cylinder bore. 

Zed Head has a great idea, search .5mm.

Or go balls out like Dizeazed and have it cut to .030 & shave the head as much as possible without shimming the cam towers. 

Good luck, hopefully this won't be a big deal bump in the road for you.

[Patcon]

my 2 cents...

Don't get distracted by the turbo, if you savings account is shallow, then turbo is not the way to go. It takes money to go this route...

I would go flat top for sure and don't be lazy! Use some of the good online engine calculators to figure out what you will have when you're finished. Figure out what compression you want to run and how to get there. You are gonna have to spend some money to build the motor and if your dollars are as limited as mine then it would be a shame to spend that money and not end up with what you want...especially for just a little home work.

Read some of the engine build threads for Diseazd he has built a number of engines...

 

 

[Diseazd]

Listen good to the advice you are getting NMcKe97.  You'll live with the engine for a long time. The P79 chambers are large....piston contact is not a problem, and even with the flat tops, you will still have a very low compression engine. 1 mm (.040 inches) overbore is the minimum I would bore....ITM Pistons have worked well for me. Nissan used flat tops in the 82 ZX's NA engines.....still was a very, very low compression engine.

[jonathanrussell]

Are you sure that Northern Auto doesn't have the ITM ry6134-20 in stock?

ITM ry6134-20

[NMcKe97]

Great idea rturbo, if I'm unable to find a set of pistons or some other alternative then I will most likley pull a head out of a yard.

I hadn't planned on going turbo (although I'd like to at some point, that or stroker) and still don't because as you and Patcon said, that takes money which is something I don't have a lot of. I more or less ment I would suffer with the low compression until I could get the parts, but forget that, sounds like it would be a while and would be a very slow and grueling time up until then.

As much as I wish I could do this build on my own time and schedule I can't because it's not my house and I currently don't have a place. I have enough funds to probably finish the motor but that's about it.

I've looked on Datsun Spirits website but it says they have no stock for 86mm or 87mm, I called them this afternoon and left a message inquiring about pistons and will follow up on it tomorrow.

I'll take a look and see if I can find any 86.5mm pistons, I hadn't considered that or done the math myself, so as you said Zed Head,  I doubt the people I'm talking to are either.

I believe we checked the taper with the new .020" rings and it all checked out within spec but I'll re do that, better safe than sorry.

I looked over ebay a few times siteunseen but I didn't see much in the .020" or .030" category, I'll give it another look and see if I missed anything.

I talked with Dave over at rebello racing and it sounded like he might have what I need, he said he would give me a call tommorow morning and let me know if he is able to get a .020" over or .5mm pistons. He recommended I use shaved turbo pistons accompanied with 240z rods if I cant find any flat tops. He said it will increase higher end torque as well so can't complain with that. The real problem then is finding l24 rods in a reasonable price range.

If you guys or anyone you know has some l24 rods laying around and are looking to part ways with them or trade them for some l28 rods I might be interested, if it sounds like somthing you're interested in send me a message or drop a comment.

I probably won't bore it out any more unless I have to just to save costs were I can, but who knows, I might have to go that route and I can't complain with a little extra umf behind each combustion cycle.

No matter which way I cut this cake money's being spent so I'm gonna do it right or not at all.

What's a safe amount of material I can take off the p79 head without having to shim the towers? I'll probably find the answer as I'm reading Diseazd's build threads but I'm gonna ask anyways .

7 hours ago, Patcon said:

and don't be lazy!

Damnit Patcon that's not what I wanted to here , but it's what I needed to here. I guess I'll be doing a little arithmetic in the next few days.

You couldn't have said it better Patcon, the last thing I want to do is assemble an engine I'm not satisfied with, I'd rather have not built the engine at all if that were the case.

I don't have any hp or compression ratio goal in mind. It's unfortunately not really a build for power, although I openly welcome it.

Mostly new oem equipment and upgrades where I can such as ARP hardware so that when I do really build it I'll have some experience and some upgrades all ready to go.

I'm rebuilding it because I already had half the block apart due to a head gasket leak so I figured I might as well go the extra mile. Plus I really wanted the knowledge and experience I'd gain from the rebuild. I figured mechanical work is a great life long skill to have so I went ahead and invested my time in it.

Up until several months ago I knew close to nothing about cars. I could change my fluids and basic maintenance but that was about the extent of it, I'd like to think I'm getting somewhat fluid in the vocabulary and understanding of things but I've still got a lot to learn.

6 hours ago, Diseazd said:

Listen good to the advice you are getting NMcKe97. 

I'm trying to digest and soak in every bit of it! I personally wouldn't invest my time and energy in something unless I was all in, so you guys have my full attention! I'm trying to put in my due time and gather all the info I can from you guys and these threads, thanks again for all the advice and info, it's really been a big help!

I assume that 87mm pistons won't be enough to throw the stock ecu off, correct me if I'm wrong,  so maybe that is the route I'll have to go, we will see.

I've only heard good things about ITM pistons so hopefully I can find some. Asides from custom and forged pistons what other brands are reliable and liked by you guys?

If the f54 p79 combo is already on the lower end of compression stock then I definitely can't go backwards and sacrifice hp, I was already using all that she had.

Unfortunately for me jonathanrussel they're out. I called and talked with 2 of their sales reps about it and they said they are out of stock and would have to call and order it from ITM. I informed them I had gotten off the phone with ITM earlier and that they are backlogged for several months and out of .020". With that in mind they said that would mean they have to wait as well.

So it sounds like I've got a few potential options now. I'll shoot for the original plan of using overbored flat tops but if that isn't able to work out atleast I've got a few other avenues I can take.

Thanks again guys for taking the time out of your day to give me a hand and share your knowledge and experience, I know I keep saying it but I really do appreciate it!

-Noah M

Edited September 15, 2017 by NMcKe97

[jonathanrussell]

Dave is a really smart guy and well respected but....given your situation I would encourage you to keep it simple and find the right pistons. They are out there on some shelf somewhere. 

And, honestly your best bet might be to take your time with this engine build and find a complete engine that is for sale but that was running recently. Folks do engine swaps in 280zs all the time. Craigslist typically has full engines for sale all the time. 

Here is a 75 L28 for sale. Not saying $900 is the right price but usually folks take less than what they advertise. Point is....engines are out there. And, if this is really a 75 L28 engine then it has a pretty nice N42 square port exhaust head. I bet in California Craigslist has lots of options.

75 L28

Edited September 15, 2017 by jonathanrussell
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[Zed Head]

You didn't mention the source below.

If you liked what you had before, and you're not looking for a big project then just rebuilding it to factory specs would be the way to go.  As soon as you start modifying, you end up on a trail of mods to make things work right with the last modification.

http://www.zcarsource.com/piston-set-280zx-020-50mm-oversize-81-83-non-turbo-new_8_55194_50979.html

[Mark Maras]

36 minutes ago, Zed Head said:

You didn't mention the source below.

If you liked what you had before, and you're not looking for a big project then just rebuilding it to factory specs would be the way to go.  As soon as you start modifying, you end up on a trail of mods to make things work right with the last modification.

http://www.zcarsource.com/piston-set-280zx-020-50mm-oversize-81-83-non-turbo-new_8_55194_50979.html

 Reminds me of a warning  that I remember in a heavy machinery operation manual. "Any primary adjustment (singular)  will be followed by secondary adjustments (plural) to compensate for the primary adjustment."  That tidbit of info turned out to be the most helpful sentence in the whole manual. I, of course, had to find out why.

[siteunseen]

1 hour ago, Mark Maras said:

I, of course, had to find out why.

[Patcon]

Cliff, that's funny...

[NMcKe97]

I'd say you guys got that right, the farther I stray from oem factory spec the more dollar signs I see. As all of you said, it's never just 1 mod.

I'd get a different block if need be but mine was in fine condition and I'm already a grip of cash deep into this build, it's almost finished, just need pistons and I'm pretty much good to go. I probably couldn't get a block if I wanted to anyways. I appreciate the recommendation though and will keep it in mind.

Unfortunately this whole build is on someone else's time so I have to get it out of there way as soon as I can, I really don't want to over stay my welcome, I've already had to have it towed a few times from other friends houses because of the time :/ .

 I knew there was another z supplier I was forgeting about, thank you Zed Head for linking me to that! I gave them a call and they only have a half set but he said they can get the other half in a week or so from ITM even though they're backlogged. He said ITM have some in a warehouse apprently, I don't know how that is because everyone I've talked to including ITM said they are out but hey works for me.

Yea the factory set up worked great for me so far so that's the route I'm looking to go. As I said earlier I openly welcome hp gains and will take them were I can but it's not my objective, later down the road I'll make my way there.

12 hours ago, Mark Maras said:

"Any primary adjustment (singular)  will be followed by secondary adjustments (plural) to compensate for the primary adjustment."

Some words of the wise right there, that will definitely come to mind anytime I'm considering mods. Thank you for sharing that great quote!

Please tell me that's a joke and you didn't get your finger lopped off siteunseen , that would be one shitty day!

After a very busy day and a number of phone calls I've gotten closer to finishing my build. Dave at rebello racing said he has a set for .030" over if I recall correctly, zcarsource has half a set in .020" over and can get the rest of the set in the following week, and my machine shop said they might have found some sealed power pistons in .020" over so I potentially have a few choices right now.

I'm thinking I will  try and get the pistons from my machine shop to start off because of convenience and if that doesn't work I'll probably get the set from Dave over at rebello racing because it's cheaper than zcarsource and a little extra BANG for your buck, litteraly.

Not that I have a large selection here and I'll probably end up with whatever I can get my hands on, but what brands of pistons do you guys prefer? I know ITM is fairly well liked and commonly used, I've heard good things about sealed power, and I forget what brand Rebello has but I imagine if they're using them it's pretty good. If it where your choice what pistons would you go with?

Once again guys thank you very much for your insight and good words, it might not be a big deal to you but it's helped me out tremendously and I can't say that enough!

-Noah M