coldturkey Posted January 6, 2011 Share Posted January 6, 2011 So im just about to put my A15 back together, checked some bearing clearances and tolerances last night and it looks gravy. I noticed however that two of the pistons have a number 2 stamped on it, the others have 1 and 3 stamped on them. So it goes 1 2 3 2 (may not be in the order that the pistons sat) They all have an "F" letter cast on the side. Since I know absolutely nothing about this sort of thing, should they not read 1-4 (i.e. the piston number) or something? And these numbers should match the numbers on the connecting rods? I suppose someone could have pulled down the engine before and replaced a piston, but its out of a stock vanette with 220kms and it blew tons of blue smoke, making me think its never been rebuilt. I kinda just want to know what the F indicates and whether they are standard pistons. The bore measured standard (78mm) but I only measured it with digital calipers once honed (fail i know). Kinda just winging it without a service manual... Quote Link to comment Share on other sites More sharing options...
RUNAMUCK Posted January 6, 2011 Share Posted January 6, 2011 Those numbers don't relate to the cylinder number. I think the "F" denotes that that side of the piston points towards the front of the block. You should be able to find imost of the info you're going to need (torque values etc) here http://datsun1200.com/modules/mediawiki ... cyclopedia Quote Link to comment Share on other sites More sharing options...
kpr Posted January 6, 2011 Share Posted January 6, 2011 if like toyota stuff, the number means piston size. bigger the number bigger the piston. not uncommon to find all different numbers in same engine Quote Link to comment Share on other sites More sharing options...
coldturkey Posted January 6, 2011 Author Share Posted January 6, 2011 if like toyota stuff, the number means piston size. bigger the number bigger the piston. not uncommon to find all different numbers in same engine But out of factory they should be identical right? Can anyone else shed some light on this? Cause if the pistons are different sizes I'd have to get all different rings to match...gah Quote Link to comment Share on other sites More sharing options...
eke_zetec_RWD Posted January 6, 2011 Share Posted January 6, 2011 measure the pistons. at the skirt below the pin. lay out small to big. measure bores and reference small to big. check cleacences are with in spec. Quote Link to comment Share on other sites More sharing options...
coldturkey Posted January 6, 2011 Author Share Posted January 6, 2011 measure the pistons. at the skirt below the pin. lay out small to big.measure bores and reference small to big. check cleacences are with in spec. Different sized pistons need different size rings though right? or am I missing something. I need new rings regardless. I can measure the pistons easily enough but cant measure the bore accurately (must obtain bore gauge). I can identify which pistons came from which cyl. May be a stupid plan (infact I know it is), but being that it was a running engine that blew smoke and didn't have an insane amount of wear on the cylinder walls was just gonna hone cylinders, replace rings, reinstall pistons. Mains and big ends were pretty worn, heaps of sludge and carbon around. Quote Link to comment Share on other sites More sharing options...
kpr Posted January 7, 2011 Share Posted January 7, 2011 still talking toyota stuff here, but the difference in piston size is very small, they use same rings for 1 2 3. sounds like similar deal in your a15. nar pretty common to find a mix of 1 2 &3's, in an unopened engine Quote Link to comment Share on other sites More sharing options...
coldturkey Posted January 7, 2011 Author Share Posted January 7, 2011 still talking toyota stuff here, but the difference in piston size is very small, they use same rings for 1 2 3. sounds like similar deal in your a15.nar pretty common to find a mix of 1 2 &3's, in an unopened engine Ahh, good call. Apparantely oversize pistons from nissan come in 0.5mm, 1.0mm oversize, of which you would need oversize rings for. According to my 4g63 manual (which I have been basing the entire build on) the piston to cylinder clearance should be 0.01-0.03mm. i.e. Sweet FA. Hope I haven't honed it out too much. Pretty much at the point where I just wanna put it together and see if it blows up. Quote Link to comment Share on other sites More sharing options...
KKtrips Posted January 7, 2011 Share Posted January 7, 2011 I am guessing they are factory markings denoting different weights perhaps?? Pistons are cast then machined to all be the same size and bores are all bored the same size on the same engine and the difference between the sizes through machining tolerances is not normally enough to measure and record. However different weights are enough to record as the consistency of the material they are cast with can vary between different positions in the mould and how fast/slow they cool compared to each other.. (amongst other factors) This is pure speculation and not based on fact though.. Quote Link to comment Share on other sites More sharing options...
coldturkey Posted January 7, 2011 Author Share Posted January 7, 2011 This is pure speculation and not based on fact though.. Good enough for me Quote Link to comment Share on other sites More sharing options...
KKtrips Posted January 7, 2011 Share Posted January 7, 2011 Oh yeah - I forgot to say that the weight is relative from piston to conrod (not from piston to piston) As long as when the manufacturers assemble the rod/piston combo to match (for example it may be something like a 1 piston with a 3 rod and a 2 piston with a 2 rod and 3 piston with a 1 rod) then they can mix those up in the engine as they please.. Quote Link to comment Share on other sites More sharing options...
coldturkey Posted January 7, 2011 Author Share Posted January 7, 2011 Oh yeah - I forgot to say that the weight is relative from piston to conrod (not from piston to piston) As long as when the manufacturers assemble the rod/piston combo to match (for example it may be something like a 1 piston with a 3 rod and a 2 piston with a 2 rod and 3 piston with a 1 rod) then they can mix those up in the engine as they please.. Interesting. Makes sense. I noticed the rods had numbers 1,2,3,4 on them though. Didn't even think about this shit tbh, I may be f***D now cause I didnt number the pistons or rod caps. Damn my she'll be right mentality.... Quote Link to comment Share on other sites More sharing options...
KKtrips Posted January 7, 2011 Share Posted January 7, 2011 The number stamped on the big end of the rod is where most people number the cylinder when the engine has been pulled apart before. The weight number (if thats what it is) will most probably be up near the gudgeon pin so all is not lost.. It is important that you have the same conrod with the same cap though - they are line bored as a pair and the difference in those is minute but enough to fuck a bearing surface quite quickly if you put the wrong cap with a non matched rod.. If you have not done that and there is no way to identify a matched pair, then you will need to take your rods to a professional engine reconditioner to get them to match them OR reline bore them if they can't identify them.. (people often stamp the cylinder number on both the rod and cap around the big end with numbers or a matching quantity of dots - as in the pic below - although the number "0" does not make much sense) Quote Link to comment Share on other sites More sharing options...
bubblegoose Posted January 7, 2011 Share Posted January 7, 2011 I just wanna put it together and see if it blows up. unless your name is runamuck then i doubt this will happen Quote Link to comment Share on other sites More sharing options...
RUNAMUCK Posted January 7, 2011 Share Posted January 7, 2011 ALL the Aseries rods I have ever seen have had the number stamped on the rod/rod caps. Without checking my w/shop manual, I think the rod oilers point to the camshaft side of the block. It's not hard to know which way around the main caps go. All the numbers face the same way, and the rear main cap can only go on one way. Last motor I freshened up, (Honed, rings, bearings, gaskets, and timing chain) only cost me about $300. It lasted a solid 400kms too. (and one drag meeting) Mind you it was running one bar of boost with no intercooler. lol If you get the basics right, the a series motor is very hard to fuck up. Do check the ring grooves though. I've found they can burn nil oil, but have quite a lot of blowby if the top ring grooves are a bit sloppy. Mind you brutally boosting used N/A pistons with maximum malice and no mechanical sympathy doesn't aid things. Quote Link to comment Share on other sites More sharing options...
RUNAMUCK Posted January 7, 2011 Share Posted January 7, 2011 Also, here is a picture I posted on another site of the cam timing. It's important that you count the links in the chain. (hence why I numbered them in the picture) Quote Link to comment Share on other sites More sharing options...
Seedy Al Posted January 7, 2011 Share Posted January 7, 2011 this is starting to seem like one of those look before you leap deals Quote Link to comment Share on other sites More sharing options...
RUNAMUCK Posted January 8, 2011 Share Posted January 8, 2011 Well if you're going to spend a few bucks on new parts, it's money for shit if you fuck up something simple and it turns out poos. I bought some parts of a guy with ADHD once. He was actually quite a nice guy, and he did me a good deal. He was "rebuilding" a motor in his shed when I turned up. I'll always try to help people with a bit of advise when I can, but he just didn't have a clue about the right and wrong way to build a motor. The block was standing on it's end on a filthy wooden garage floor. He was cleaning nothing, and tapping the new bearing shells into the block with a hammer and screw driver. I could see how stoked he was that he was going to have an "sweet rebuilt engine" for his car. I had to just bite my lip, wish him well and be on my way. I ALWAYS remember that when I see an engine advertised as having been "rebuilt". Quote Link to comment Share on other sites More sharing options...
coldturkey Posted January 9, 2011 Author Share Posted January 9, 2011 OK so update: The cylinder number IS stamped on both the rods and caps!! Win! I got quoted $170 from a mate for full head set, rear main seal, sump gasket, rings set, mains and big ends Which is pretty mint! I'm fairly confident it will last longer than 400kms, but thanks for that timing chain picture, thats another thing which I basically just pulled off without too much though and the "she'll be right" mentality. Hmm, by "check ring grooves" you mean check the wobble clearance when the rings are in place? To be honest if I make it that far and find out they are too loose, im jsut gonna put it back together instead of trying to find new pistons. Anyone got a ring expander I can borrow or know where I can get one? Do you even need to use one? My guess would be yes, as I managed to break half the rings when taking them off. Quote Link to comment Share on other sites More sharing options...
coldturkey Posted January 9, 2011 Author Share Posted January 9, 2011 OK so update:The cylinder number IS stamped on both the rods and caps!! Win! I got quoted $170 from a mate for full head set, rear main seal, sump gasket, rings set, mains and big ends Which is pretty mint! I'm fairly confident it will last longer than 400kms, but thanks for that timing chain picture, thats another thing which I basically just pulled off without too much thought and the "she'll be right" mentality. Hmm, by "check ring grooves" you mean check the wobble clearance when the rings are in place? To be honest if I make it that far and find out they are too loose, im jsut gonna put it back together instead of trying to find new pistons. Anyone got a ring expander I can borrow or know where I can get one? Do you even need to use one? My guess would be yes, as I managed to break half the rings when taking them off. Quote Link to comment Share on other sites More sharing options...
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