rchrd989 Posted October 26, 2006 Share Posted October 26, 2006 Heres whats going on, I have a L28 that I bought a little while back that I was gonna put in my 240z with a E88 head. The guy i bought it from was some punk kid about my age who had a bunch of Z parts. He said his uncle rebuilt it 40,000 miles ago, so getting the motor for $150 seemed like a good deal. Well lately Ive been looking more and more at the motor, looking at the cylinders and seeing no satching left at all... the pistons are nice and black but I decide that Im going to rebuild it anyway because of the cylinders being so smooth. I take out piston number 6 and one of the rings is completly broken in half. I bring it to the bench and grab my measuring calliper. I read in my "How to rebuild your nissan and datsun OHC engine" book that the L28 has a 3.386" bore. Well I go measure my cylinder and it measures to be 3.412 and the piston measures at 3.396 Also the pistons are completly flat, they are not like the pistons I pulled out of my L24. Could you guys help me out? Am i dealing with stock 280z stuff or am I dealing with more, I really need to know so I can order some parts... Thanks guys Richard Quote Link to comment Share on other sites More sharing options...
naviathan Posted October 27, 2006 Share Posted October 27, 2006 Given the measurements you'r talking about it looks like it a .026 overbore with flat top pistons. I'm not sure baout those bore sizes. 86mm (metric size of the cylinder) converts to 3.3884", which is only slightly higher than what the book says, but that would also leave the pistons too large for a stock bore, but barely. The might be after market flat tops meant for an overbore. Of course they could even be advance auto parts specials which means you're still looking at a shooting match as to what they really are. Are there any marking on the pistons? Casting numbers, manufacturers initial, part number? Anything? You're not dealing with stock, but that doens't mean it's performance either. Quote Link to comment Share on other sites More sharing options...
rchrd989 Posted October 27, 2006 Author Share Posted October 27, 2006 Ive been gone the past two days or so so I havent cleaned them up real good yet, but so far I havent seen any markings such as std or .02 the rod has 12-1(some symbol, looks almost like a chevy emblem) then A87-2 and on the inside of th skirt it has N8601 and N8600 Quote Link to comment Share on other sites More sharing options...
rchrd989 Posted October 27, 2006 Author Share Posted October 27, 2006 I just cleaned up the top of the piston real quick and it has .75 stamped on the edge near like a notch or groove that all the pistons have. Quote Link to comment Share on other sites More sharing options...
naviathan Posted October 27, 2006 Share Posted October 27, 2006 Do all of them have N8601 and N8600? N8600 is an l28e piston and n8601 is an RB30 piston. Quote Link to comment Share on other sites More sharing options...
rchrd989 Posted October 27, 2006 Author Share Posted October 27, 2006 I only have one piston pulled, those numbers are both on the one piston right next eachother. Quote Link to comment Share on other sites More sharing options...
naviathan Posted October 27, 2006 Share Posted October 27, 2006 That's odd. They're both part numbers, but to different engines. Unless they're both the same size even though they're different blocks. Quote Link to comment Share on other sites More sharing options...
rchrd989 Posted October 27, 2006 Author Share Posted October 27, 2006 yea I dont know, the numbers are one on top of the other, do you think that the .75 stamped on the piston top would possibly be it being .75mm over? Quote Link to comment Share on other sites More sharing options...
rchrd989 Posted October 29, 2006 Author Share Posted October 29, 2006 So I looked in my conversion table and .75 is equal to .03 and 3.412 minus 3.386 is equal to .026 like you said. So im going to be needing new rings, where would you guys reccomend getting rings at, Ive looked all over online and i only can find .02 rings and .04 rings... where should I look, ive looked all over thanks, Richard Quote Link to comment Share on other sites More sharing options...
naviathan Posted October 29, 2006 Share Posted October 29, 2006 You'll be hard pressed to find .026 over rings. You can try the .020 over and see if they're still within spec. My recommendation would be to find a more common diameter piston and bore the block to match. Quote Link to comment Share on other sites More sharing options...
rchrd989 Posted October 30, 2006 Author Share Posted October 30, 2006 Im taking that the .75 on the top of the piston means .75mm oversized. I looked in my black dragon auto catolog and they sell piston rings that are .75mm over. So im just gonna buy those and I think it will work out, thanks alot. Richard Quote Link to comment Share on other sites More sharing options...
naviathan Posted October 30, 2006 Share Posted October 30, 2006 That could very well be. .75mm is .030in over bore. That would be about right for what you're looking at. Go for it and let me know how it works out. Quote Link to comment Share on other sites More sharing options...
rchrd989 Posted October 31, 2006 Author Share Posted October 31, 2006 Will do, As of right now I have the motor almost completly torn down, I have everything removed other than the crankshaft, I can get all of the caps off except for the rear main seal cap and the main cap, I dont have a puller that works but Im going to try and make one tomorow our of some flat steel and some bolts Quote Link to comment Share on other sites More sharing options...
rchrd989 Posted November 1, 2006 Author Share Posted November 1, 2006 So flat steel didnt work, but I did make a succesful puller out of some square stock and some bolts and got the two caps off easily, Now I jsut have to wait for some parts and the process will continue! Quote Link to comment Share on other sites More sharing options...
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