Guest 73Turbo240z Posted April 14, 2005 Share Posted April 14, 2005 I went to my engine builder today to drop everything off... told him we'd need to bore my block .010 over to fit the pistons, he measured the diameter of the cylinder bore, and said it was too close to get a good fit, that it would need to be bored to another size up .020+, so i'm a little frustrated figuring i just wasted money buying AZ car pistons, and then having them coated with ceramic and friction reduction coatings. So i come home to start searching to see what i can do, and check AZ car's website to see that they list as being 1mm bigger, (.040) per the website listing. Now i could swear i ordered .010 over back in the day, and he's never offered more than one size to my knowledge, so am i on crack here and they've always been .040, or did he change sizes recently? i need to sort this out ASAP cause if these really are .040 pistons i should be able to just bore out the block and be good to go... input anyone? stock diameter of the L28 piston/bore is 86mm correct? which would make the .040 AZ car pistons accurate information right? i'm hoping this is all just cause of miscommunication and that i'm not gonna have to sell over $900 worth of pistons to get somthing else. Quote Link to comment Share on other sites More sharing options...
technicalninja Posted April 14, 2005 Share Posted April 14, 2005 Normal oversizes for Japanese pistons are .5 mm and 1.0 mm which equal .020 and .040 inches respectively. In 20+ years of import rebuilding I have never seen a set (nissan or otherwise) which is .010 inch over stock. This would be .25 mm over, maybe it was available in the past but not to my knowledge. Measure your pistons, I bet they are .020 and should met your machinist's wants. Quote Link to comment Share on other sites More sharing options...
getZ Posted April 14, 2005 Share Posted April 14, 2005 over the last year I have only seen AZ car forged pistons as 1.0mm /.040 inches for an overbore. Have the engine bored out and you should be good to go. Quote Link to comment Share on other sites More sharing options...
Guest 73Turbo240z Posted April 14, 2005 Share Posted April 14, 2005 and .040 over is in correct reference reffered to as going "four over" right? this guys a little backwoods, nice guy, but i want to make sure were speaking the same lingo. Quote Link to comment Share on other sites More sharing options...
texasz Posted April 14, 2005 Share Posted April 14, 2005 First off you can either just call AZ Z Car and ask, or measure your pistons (or have the engine builder measure them). Easy solution. and .040 over is in correct reference reffered to as going "four over" right? this guys a little backwoods, nice guy, but i want to make sure were speaking the same lingo. In metric terms "four over" means 4mm which is right on the edge of how much you can go. 3mm takes you to 89mm which are the 240SX pistons used in 3.1L stokers, 4mm takes you to 90mm which are the size pistons used in the 3.2L strokers. Hope this helps. Quote Link to comment Share on other sites More sharing options...
Guest 73Turbo240z Posted April 14, 2005 Share Posted April 14, 2005 alright measured w/ a digital caliper this morning... ranged from 87.17 to 87.20, so this concur's w/ the AZCar site which lists them as 1mm bigger (.040) or "4 over", 87mm pistons... what determines the "over" size, i know its mathmatical, but to be honest i've always been god awful at math, so i need a little help understanding this before i call my machinist again and try to keep up w/ him in a conversation. Quote Link to comment Share on other sites More sharing options...
zcarmark Posted April 14, 2005 Share Posted April 14, 2005 I have a brand new set Arizona Z fordged pistons .040 over. Let me know if you are interstead. I waiting for my rb26 to show up. also have lots of other L28et parts. Quote Link to comment Share on other sites More sharing options...
Guest 73Turbo240z Posted April 14, 2005 Share Posted April 14, 2005 got it all squared away, it was just miscommunication like i figured, they'll work fine... motors finally going together... now i just have to find a EFI fuel tank or fuel cell, and work out the dark art of megasquirt... Quote Link to comment Share on other sites More sharing options...
Dan Baldwin Posted April 14, 2005 Share Posted April 14, 2005 .040 is FORTY over, not four over. As in, forty thousandths. Quote Link to comment Share on other sites More sharing options...
4everDATSUN Posted April 14, 2005 Share Posted April 14, 2005 thanks for that bit of knowledge dan Quote Link to comment Share on other sites More sharing options...
Guest 73Turbo240z Posted April 14, 2005 Share Posted April 14, 2005 .040 is FORTY over, not four over. As in, forty thousandths. see thats how i was saying it, and all i got was a wierd look from my machinist so i reverted to saying complete number sequences, he referred to things in .5 and 1 over sizes, which after diggin through the factory service manual, that's how they reffered to it also was by .5 and 1 over sizing, though to the immidiate right of that it read out in the .0XX sizing terms i was familiar with... reference Normal oversizes for Japanese pistons are .5 mm and 1.0 mm which equal .020 and .040 inches respectively.In 20+ years of import rebuilding I have never seen a set (nissan or otherwise) which is .010 inch over stock. This would be .25 mm over' date=' maybe it was available in the past but not to my knowledge. Measure your pistons, I bet they are .020 and should met your machinist's wants.[/quote'] difference in generations of car folks i suppose, the guy is really nice though, knows ton's about the L series, and from the looks of the shop they build a number of high output motors, anything from big blocks to 1.5l 4cyls, they've squeezed somthing outta them all. Quote Link to comment Share on other sites More sharing options...
texasz Posted April 15, 2005 Share Posted April 15, 2005 In metric terms "four over" means 4mm which is right on the edge of how much you can go. 3mm takes you to 89mm which are the 240SX pistons used in 3.1L stokers, 4mm takes you to 90mm which are the size pistons used in the 3.2L strokers. Hope this helps. Did anyone read this the first time? It explains what the xxx over means in metric terms. Quote Link to comment Share on other sites More sharing options...
Guest 73Turbo240z Posted April 15, 2005 Share Posted April 15, 2005 Did anyone read this the first time? It explains what the xxx over means in metric terms. i missed it completely, sorry about that lol, i was kinda stressing out about the potential non-working pistons... thanks for the help though! Quote Link to comment Share on other sites More sharing options...
arizonazcar Posted April 29, 2005 Share Posted April 29, 2005 The pistons we sell are forged flat-tops that are 87mm which is 1.0mm (.040") over bore for a stock L-28. They are setup for zero deck height with L-28 crank and L-24 conrods. They are $629.00 for the set of 6 with rings and pins see http://www.arizonazcar.com/piston.html Dave Quote Link to comment Share on other sites More sharing options...
Guest 73Turbo240z Posted April 29, 2005 Share Posted April 29, 2005 yep, big thanks to dave everyone btw... he was really prompt about answering questions i had when all this was going on, very good customer service, and i'm happy to report i'm being told the block will be out of machining and ready for me to take delivery next week! The pistons we sell are forged flat-tops that are 87mm which is 1.0mm (.040") over bore for a stock L-28. They are setup for zero deck height with L-28 crank and L-24 conrods.They are $629.00 for the set of 6 with rings and pins see http://www.arizonazcar.com/piston.html Dave Quote Link to comment Share on other sites More sharing options...
texasz Posted April 29, 2005 Share Posted April 29, 2005 The pistons we sell are forged flat-tops that are 87mm which is 1.0mm (.040") over bore for a stock L-28. They are setup for zero deck height with L-28 crank and L-24 conrods.They are $629.00 for the set of 6 with rings and pins see http://www.arizonazcar.com/piston.html Dave Too bad they're not 89mm pistons...I'm working on a 3.1L stroker and may have been intersted. Quote Link to comment Share on other sites More sharing options...
Tony D Posted April 29, 2005 Share Posted April 29, 2005 I have never bored a block before having the pistons to in hand. I don't see how anyone could do anything but a rough bore until having the pistons anyway. The final hone is done ot fit each cylinder individually. At least that is the only way I have ever done it. Quote Link to comment Share on other sites More sharing options...
280Zen Posted April 29, 2005 Share Posted April 29, 2005 The pistons we sell are forged flat-tops that are 87mm which is 1.0mm (.040") over bore for a stock L-28. They are setup for zero deck height with L-28 crank and L-24 conrods ok, Im probably worse at math then 73turbo240z, what will this bring the compression to? Quote Link to comment Share on other sites More sharing options...
Guest 73Turbo240z Posted April 29, 2005 Share Posted April 29, 2005 I have never bored a block before having the pistons to in hand. I don't see how anyone could do anything but a rough bore until having the pistons anyway. The final hone is done ot fit each cylinder individually. At least that is the only way I have ever done it. the pistons were in hand, in a blonde moment niether myself or the machinist thought to take a caliper to the piston itself to verify the data... i had all my ducks in a row parts wise, just had a mix up in the initial data that we thought was accurate, it's all hunky dorey now. Quote Link to comment Share on other sites More sharing options...
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